Plasmodium. These parasites are transmitted by the bite of an infective female Anopheles species mosquito. The majority of malaria infections in the United States occur among persons who have traveled to regions with ongoing malaria transmission. However, malaria is occasionally acquired by persons who have not traveled out of the country through exposure to infected blood products, congenital transmission, nosocomial exposure, or local mosquitoborne transmission. Malaria surveillance in the United States is conducted to provide information on its occurrence , guide prevention and treatment recommendations for travelers and patients, and facilitate rapid transmission control measures if locally acquired cases are identified.Malaria in humans is caused by intraerythrocytic protozoa of the genus This report summarizes confirmed malaria cases in persons with onset of illness in 2017 and trends in previous years.Malaria cases diagnosed by blood film microscopy, polymerase chain reaction, or rapid diagnostic tests are reported to local and state health departments through electronic laboratory reports or by health care providers or laboratory staff members. Case investigations are conducted by local and state health departments, and reports are transmitted to CDC through the National Malaria Surveillance System (NMSS), the National Notifiable Diseases Surveillance System (NNDSS), or direct CDC consultations. CDC reference laboratories provide diagnostic assistance and conduct antimalarial drug resistance marker testing on blood samples submitted by health care providers or local or state health departments. This report summarizes data from the integration of all cases from NMSS and NNDSS, CDC reference laboratory reports, and CDC clinical consultations.P. falciparum accounted for the majority of infections , followed by P. vivax (216 [10.0%]), P. ovale (119 [5.5%]), and P. malariae (55 [2.6%]). Infections by two or more species accounted for 22 cases (1.0%). The infecting species was not reported or was undetermined in 226 cases (10.5%). CDC provided diagnostic assistance for 9.5% of confirmed cases and tested 8.0% of specimens with P. falciparum infections for antimalarial resistance markers. Most patients (94.8%) had symptom onset <90 days after returning to the United States from a country with malaria transmission. Of the U.S. civilian patients who reported reason for travel, 73.1% were visiting friends and relatives. The proportion of U.S. residents with malaria who reported taking any chemoprophylaxis in 2017 (28.4%) was similar to that in 2016 (26.4%), and adherence was poor among those who took chemoprophylaxis. Among the 996 U.S. residents with malaria for whom information on chemoprophylaxis use and travel region were known, 93.3% did not adhere to or did not take a CDC-recommended chemoprophylaxis regimen. Among 805 women with malaria, 27 reported being pregnant. Of these, 10 pregnant women were U.S. residents, and none reported taking chemoprophylaxis to prevent malaria. A total of 26 (1.2%) malaria cases occurred among U.S. military personnel in 2017, fewer than in 2016 (41 [2.0%]). Among all reported cases in 2017, a total of 312 (14.4%) were classified as severe malaria illnesses, and seven persons died. In 2017, CDC analyzed 117 P. falciparum-positive and six P. falciparum mixed-species samples for antimalarial resistance markers ; identification of genetic polymorphisms associated with resistance to pyrimethamine were found in 108 (97.3%), to sulfadoxine in 77 (69.4%), to chloroquine in 38 (33.3%), to mefloquine in three (2.7%), and to atovaquone in three (2.7%); no specimens tested contained a marker for artemisinin resistance. The data completeness of key variables  was lower in 2017 (74.4%) than in 2016 (79.4%).CDC received reports of 2,161 confirmed malaria cases with onset of symptoms in 2017, including two congenital cases, three cryptic cases, and two cases acquired through blood transfusion. The number of malaria cases diagnosed in the United States has been increasing since the mid-1970s; in 2017, the number of cases reported was the highest in 45 years, surpassing the previous peak of 2,078 confirmed cases reported in 2016. Of the cases in 2017, a total of 1,819 (86.1%) were imported cases that originated from Africa; 1,216 (66.9%) of these came from West Africa. The overall proportion of imported cases originating from West Africa was greater in 2017 (57.6%) than in 2016 (51.6%). Among all cases, The number of reported malaria cases in 2017 continued a decades-long increasing trend, and for the second year in a row the highest number of cases since 1971 have been reported. Despite progress in malaria control in recent years, the disease remains endemic in many areas globally. The importation of malaria reflects the overall increase in global travel to and from these areas. Fifty-six percent of all cases were among persons who had traveled from West Africa, and among U.S. civilians, visiting friends and relatives was the most common reason for travel (73.1%). Frequent international travel combined with the inadequate use of prevention measures by travelers resulted in the highest number of imported malaria cases detected in the United States in 4 decades.P. vivax infections in those aged >16 years and should be co-administered with chloroquine . In April 2019, intravenous artesunate became the first-line medication for treatment of severe malaria in the United States. Artesunate was recently FDA approved but is not yet commercially available. The drug can be obtained from CDC under an investigational new drug protocol. Detailed recommendations for preventing malaria are available to the general public at the CDC website . Health care providers should consult the CDC Guidelines for Treatment of Malaria in the United States and contact the CDC’s Malaria Hotline for case management advice when needed. Malaria treatment recommendations are available online  and from the Malaria Hotline (770-488-7788 or toll-free 855-856-4713). Persons submitting malaria case reports  should provide complete information because incomplete reporting compromises case investigations and efforts to prevent infections and examine trends in malaria cases. Molecular surveillance of antimalarial drug resistance markers  enables CDC to track, guide treatment, and manage drug resistance in malaria parasites both domestically and internationally. More samples are needed to improve the completeness of antimalarial drug resistance analysis; therefore, CDC requests that blood specimens be submitted for any case of malaria diagnosed in the United States.The best way to prevent malaria is to take chemoprophylaxis medication during travel to a country where malaria is endemic. Adherence to recommended malaria prevention strategies among U.S. travelers would reduce the numbers of imported cases; reasons for nonadherence include prematurely stopping after leaving the area where malaria was endemic, forgetting to take the medication, and experiencing a side effect. Travelers might not understand the risk that malaria poses to them; thus, health care providers should incorporate risk education to motivate travelers to be adherent to chemoprophylaxis. Malaria infections can be fatal if not diagnosed and treated promptly with antimalarial medications appropriate for the patient’s age, medical history, the likely country of malaria acquisition, and previous use of antimalarial chemoprophylaxis. Antimalarial use for chemoprophylaxis and treatment should be informed by the most recent guidelines, which are frequently updated. In 2018, two formulations of tafenoquine  were approved by the Food and Drug Administration (FDA) for use in the United States. Arakoda was approved for use by adults for chemoprophylaxis; the regimen requires a predeparture loading dose, taking the medication weekly during travel, and a short course posttravel. The Arakoda chemoprophylaxis regimen is shorter than alternative regimens, which could possibly improve adherence. This medication also might prevent relapses. Krintafel was approved for radical cure of  Plasmodium genus are transmitted through the bite of infective mosquitoes. Female Anopheles species mosquitoes transmit four Plasmodium species that commonly cause illness in humans: P. falciparum, P. vivax, P. ovale, and P. malariae. Mixed infections with multiple species are possible and occur in areas where more than one species is in circulation  that can reactivate months or years after the acute infection. P. malariae parasites are found throughout the tropics and subtropics, account for a minority of the Plasmodium parasites in circulation, and are often detected in mixed-species infections. P. malariae parasites mature slowly in human and mosquito hosts and, although they do not typically cause severe symptoms in humans, can result in persistent low-density infections that can last for years or even a lifetime, providing opportunities for ongoing transmission and health sequelae  estimated that 219 million cases of malaria occurred worldwide in 2017, resulting in an estimated 400,000 deaths .To prevent malaria, CDC recommends that U.S. residents use chemoprophylaxis: antimalarial medication taken before, during, and after travel to a country with malaria transmission. Persons who intend to travel should ask their physician for a prescription for an antimalarial that is appropriate for the region of travel, the age of the patient, pregnancy status, and individual preferences . CDC provides chemoprophylaxis guidelines to health care providers and the public, and links to these resources can be found at the end of this report. Although avoiding mosquito bites is not possible in many transmission settings, travelers should consider mosquito avoidance measures, specifically the use of repellents, treating clothing with permethrin, sleeping in screened sleep spaces, and using an insecticide-treated bed net  and the National Notifiable Diseases Surveillance System (NNDSS)  was used to describe the proportion of variation explained by the model. States with one or more cases were categorized into quartiles using the QNTLDEF=5 option in SAS .The chi-square test was used to calculate p values and assess differences between variables reported in 2017 compared with previous years. A p value of <0.05 was considered statistically significant. Linear regression using the least-squares method was used to assess the linear trend in the number of cases during 1973–2017. The Pearson product-moment correlation coefficient  to the question, “Was chemoprophylaxis taken as prescribed?”Confirmed case: Symptomatic or asymptomatic infection that occurs in a person in the United States or one of its territories who has laboratory-confirmed (by microscopy or PCR) malaria parasitemia, regardless of whether the person had previous episodes of malaria while in other countries. A subsequent episode of malaria is counted as an additional case, regardless of the detected Plasmodium species, unless the case is indicated as a treatment failure within 4 weeks of initial presentation.Laboratory criteria for diagnosis: Demonstration of malaria parasites by microscopy or PCR .Non-U.S. residents: Persons who are residents of a country other than the United States. Immigrants and refugees who are establishing residence in the United States are classified as non-U.S. residents if their exposure occurred while they were residents in their originating country.Suspect case: A positive malaria RDT result in a person in the United States or one of its territories without confirmation by microscopy or PCR, regardless of whether the person experienced previous episodes of malaria while in other countries.Transfusion transmitted malaria (TTM): A Plasmodium infection that is accidentally caused by the transfusion of whole blood or blood components from an infected donor to a recipient : Treated with a CDC-recommended regimen appropriate for species, region, and severity of disease : Treatment to kill dormant liver-stage parasites (hypnozoites) of P. vivax and P. ovale to prevent relapses of malaria.Relapsing malaria: Recurrence of disease after it has been apparently cured. In malaria, true relapses are caused by activation of dormant liver-stage parasites (hypnozoites) of P. vivax and P. ovale only. Hypnozoite activation is typically delayed after the primary exposure , acute respiratory distress syndrome (ARDS), jaundice, or ≥5% parasitemia (Travelers visiting friends and relatives (VFR): Immigrants, ethnically and racially distinct from the major population of the country of residence , who return to their homeland  to visit friends and relatives; family members of immigrants  are included in this group, even if they were born in the country of residence  microscopic analysis of a peripheral blood smear , 2) PCR, and 3) RDT; a blood smear is recommended as the preferred first-line test. If malaria is suspected, a Giemsa-stained film of the patient’s peripheral blood should be examined by microscopy for parasites as soon as possible. Microscopy allows an estimation of the level of parasitemia, which is necessary to prescribe appropriate treatment. Diagnostic accuracy depends on blood film quality and examination by experienced laboratory personnel  detects circulating malaria-specific antigens and is the only RDT approved by the Food and Drug Administration (FDA) for use by hospital and commercial laboratories; the test is not approved as a point-of-care test by clinicians or the general public , pyrimethamine and proguanil , sulfadoxine , atovaquone , mefloquine , and artemisinin  are analyzed for polymorphisms by comparing each sequence to the reference genome. The sequence data are analyzed using Geneious Pro R8 (Biomatters).Samples for molecular resistance monitoring are processed for PCR amplification of parasite DNA using appropriate primers for the genes of interest in nested PCR assays as previously described  method as previously described  (2 = 0.884). In contrast, the trajectory of the accumulation of military and non-U.S. cases is flat during this period   , and in ctively) . The incIn 2017, a total of 1,290 (59.7%) cases occurred among U.S. civilians, 26 (1.2%) among U.S. military members, 516 (23.9%) among non-U.S. residents, and 329 (15.2%) among patients with unknown or unreported resident status . Of the Plasmodium species  cases reported to CDC included information on the infecting  species , which iP. falciparum  P. vivax infections. During 2012–2017, there was a decreasing proportion of P. vivax cases, with an average loss of 10.1 each year. In 2017, a total of 119 (6.2%) P. ovale, 55 (2.8%) P. malariae, and 22 (1.1%) mixed-species infections were identified. Of the 22 mixed infections, nine were P. falciparum with P. malariae, five were P. falciparum with P. vivax, four were P. malariae with P. ovale, three were P. falciparum with P. ovale, and one was P. falciparum, P. ovale, and P. malariae. Of 22 mixed infections, 19 were PCR confirmed, seven of these by the CDC reference laboratory, including the specimen positive for three Plasmodium species. The species distribution in 2017 for P. falciparum, P. vivax, P. ovale, P. malariae¸ mixed Plasmodium species, and unknown species infections was similar to the 2016 distribution. During 2012–2017, the proportion of unspeciated cases decreased, with a 20.8% decrease in cases per year. Because of the small number of P. ovale, P. malariae, and mixed-species infections detected each year, proportional changes over time were not assessed for these infections.Among the 1,935 cases with a species determination, 1,523 (78.7%) were lciparum . During P. falciparum and P. vivax infections were PCR confirmed . Of 55 P. malariae cases, 28 (50.9%) were PCR confirmed; 55 (46.2%) of 119 P. ovale infections were PCR confirmed, and 19 (86.4%) of 22 mixed species infections were PCR confirmed. Of 226 unspeciated infections, 18 (8.0%) were PCR confirmed to the Plasmodium genus only.In 2017, a total of 764 (35.4%) malaria infections reported in the United States were confirmed by PCR, a similar proportion to 2016, when 717 of 2,078 (34.5%) infections were PCR confirmed. Approximately one third of Information on the region of acquisition was available for 2,073 (98.2%) of 2,112 imported cases; of these, 1,819 (87.8%) were from Africa, 181 (8.7%) from Asia, 37 (1.8%) from South America, 30 (1.5%) from Central America and the Caribbean, and six (<1.0%) from Oceania .P. falciparum cases reported in 2017 with a known region of acquisition, 1,435 (97.5%) were acquired from Africa, 17 (1.2%) from Central America and the Caribbean, 13 (0.9%) from Asia, six (<1.0%) from South America, and one from Oceania (<1.0%). P. falciparum infections accounted for 78.9% of the cases imported from Africa, 7.2% from Asia, 56.7% from Central America and the Caribbean, 16.2% from South America, and 16.7% from Oceania  were acquired from Asia, followed by 34 (16.4%) from Africa, 29 (13.9%) from South America, nine (4.3%) from Central America and the Caribbean, and four (1.9%) from Oceania. In 2017, a total of 114 P. ovale and 50 P. malariae infections were reported with information about the region of acquisition; 113 (99.1%) and 48 (96.0%) were acquired from Africa, respectively. The geographical area of acquisition was reported for all 22 mixed-species infections; 20 (90.9%) mixed-species infections were acquired from Africa and two (9.1%) from Asia . However, in 2017, the proportion of cases imported from West Africa increased; 1,216 (57.6%) of all cases were imported from West Africa in 2017, compared with 1,061 (51.6%) in 2016. Of the five countries most commonly reported as the country of acquisition in 2017, four were in West Africa . A total of 147 persons had traveled to Cameroon, in Central Africa, in 2017. Compared with 2016, an increase of at least 20 additional cases were imported from the following African countries in 2017: Nigeria (55 more), Liberia (36 more), Ivory Coast (30 more), Sierra Leone (27 more), Cameroon (25 more), and Ghana (20 more). Kenya, Togo, and Zimbabwe all had five to nine more cases in 2017 than in 2016. Countries in Africa with fewer cases imported into the United States in 2017 than in 2016 included Uganda (40 fewer), Democratic Republic of Congo (30 fewer), Tanzania (23 fewer), Ethiopia (20 fewer), Chad (12 fewer), and Burkina Faso (10 fewer). Niger, Senegal, Gabon, and South Sudan all had five to nine fewer cases imported in 2017 than in 2016.The number and proportion of cases imported from Asia were similar in 2017 compared with 2016 . The greatest number of cases imported from this region were from India, with 105 cases in 2017 and 89 cases in 2016. Cases imported from Afghanistan increased from 39 in 2016 to 48 in 2017. No cases were acquired from South Korea in 2017, compared with 10 in 2016.The proportion of imported cases from Central America and the Caribbean decreased from 70 cases in 2016 to 30 cases in 2017. Among the seven countries in Central America and the Caribbean from which cases of malaria were acquired in 2016 and 2017, the number of cases decreased in six , and one case was reported from Nicaragua in both 2016 and 2017. In 2017, fewer than half as many cases were reported from the Central American region (35 cases in 2016 and 13 cases in 2017) and from the Caribbean region (35 cases in 2016 and 17 cases in 2017).P. falciparum species (Of the 17 cases from the Caribbean region (Haiti and the Dominican Republic), 16 (94.1%) were  species . The numP. vivax, one was P. falciparum, and three were unspecified species. Among cases acquired from Central America, one severe case (of unknown species) was acquired from Guatemala. Of persons with malaria who had traveled from Central America, six were refugees or immigrants, three had traveled for tourism, two had traveled as missionaries, and two had traveled to visit friends and family.Of 13 cases from Central America, nine were P. vivax, six were P. falciparum, and two did not have the infecting species determined; two patients, both with travel to Guyana, had severe P. vivax infection. VFR travel and tourism were reported as reasons for travel by nine persons each, two persons traveled as missionaries, and 17 persons had unknown or other reasons for travel to South America.During both 2016 and 2017, a total of 37 cases were imported from South America each year. In both years, Guyana, Peru, and Brazil were the sources of the majority of the cases acquired in South America. In 2017, a total of 17 cases from Guyana, seven from Peru, and six from Brazil were reported. Of 37 infections acquired in South America, 29 were P. vivax, one was P. falciparum, and one was reported with the species not determined. None of these patients had severe illness. Of the six patients, two had traveled as missionaries, and one each traveled to visit friends and family, for business, for education (as a teacher or student), and for an unknown reason.As in 2016, six cases were reported from Oceania in 2017, all of them from Papua New Guinea; four of six cases were Confirmed cases were classified according to location of diagnosis or residence of the infected person. In 2017, Wyoming was the only state that did not report at least one case of malaria. States reporting one or more cases were categorized into quartiles ; the 13 Among 2,112 imported cases, information on residence status was available for 1,823 (86.3%) cases; of these, 1,308 (71.8%) persons were U.S. residents (civilian and military) and 515 (28.3%) were non-U.S. residents . In 2017Most malaria cases imported among the 515 non-U.S. residents in 2017 were from Africa (397 [77.1%]), followed by Asia (89 [17.3%]) and the Americas and Caribbean (23 [4.5%]) . Among nIn 2016, after a decrease in imported malaria cases acquired from West Africa in 2015 because of the Ebola virus disease outbreak and travel restrictions  of 603 cases imported in July and August 2017 and 166 (65.1%) of 255 cases in February, March, and December 2017. P. vivax and P. ovale infections were combined because the illnesses can have a delayed initial onset after infection or can result from a relapse, which might show as a secondary peak in the timeline of infections. In 2017, the mean number of P. vivax and P. ovale cases was 25.8 per month; the maximum numbers occurred in July and August . Monthly numbers of P. vivax and P. ovale cases were above the mean during May–September.In 2017, the peak of travel for U.S. citizens to Africa occurred in the summer months, with a total of approximately 44,000 flight departures in June and 46,000 in July. In August, approximately 40,000 departures were reported . The lowPlasmodium species determination, 1,475 (77.9%) had complete information on return travel and illness onset dates, allowing for calculation of the interval between these dates  had symptom onset before or within 29 days of arrival in the United States. In contrast, 58 (40.6%) of 143 P. vivax patients and 42 (52.5%) of 80 P. ovale patients had illness onset ≥30 days after arrival in the United States, consistent with the potential for these species to relapse because of the persistence of liver hypnozoites or to have an extended incubation period before symptom onset  of 26 cases among military personnel diagnosed in the United States in 2017. Of these, 12 (54.6%) were P. falciparum, five (22.7%) were P. ovale, three (13.6%) were P. vivax, and two (9.1%) were P. malariae. Of 26 military cases, seven were PCR confirmed .In 2017, a total of 26 cases of malaria diagnosed in the United States occurred among U.S. military personnel, a decrease compared with 41 cases reported in 2016 . In 2017, a total of 20 cases of malaria among U.S. military members were acquired from Africa, three cases were acquired from Asia, and for three cases the country or region of acquisition was unknown. Among cases acquired from Africa, five were acquired among service personnel traveling to Cameroon; four to Nigeria; two each to Liberia, Sierra Leone, and unspecified Africa; and one each to Ghana, Ivory Coast, Tanzania, Togo, and Uganda. The regional proportions of where malaria was acquired by U.S. military members were different in 2017 compared with 2016. In 2016, equal numbers of cases were acquired from Africa and Asia (17 cases [41.5%] each). In 2017, a total of 20 (76.9%) cases were acquired from Africa, and three (11.5%) were from Asia. A total of 11 (42.3%) cases were from West Africa in 2017, whereas five (12.2%) cases were from West Africa in 2016. No cases of malaria reported among service members from South Korea in 2017, whereas 10 cases were reported in 2016. In 2017, three cases were acquired from Afghanistan, compared with seven in 2016. Malaria was acquired by six military personnel during personal leave each year in 2016 and 2017. The P. vivax or P. ovale diagnoses, three reported taking primaquine to prevent a relapse.Reports for 24 (92.3%) military patients had information on chemoprophylaxis use; 11 did not take an antimalarial medication to prevent malaria. Of the 10 patients who took chemoprophylaxis and whose region of travel was known, nine took an appropriate regimen for the region of travel: six took doxycycline, two took atovaquone-proguanil, and one patient took two or more medications for chemoprophylaxis. The chemoprophylaxis medication was not specified for three patients. Of seven patients with information on chemoprophylaxis adherence, five reported missing doses. Of the 19 military members who had traveled to Africa and had information available on chemoprophylaxis use, nine (47.4%) reported taking chemoprophylaxis. Of three military patients who had traveled to Asia, two (66.7%)reported taking chemoprophylaxis. Of eight military patients with P. falciparum. Of these four patients, three had documented hyperparasitemia (≥5% red blood cells infected), and three were treated with an intravenous antimalarial ; one patient with 9.2% parasitemia had traveled to visit friends and family while on leave from the military and after receiving the diagnosis was treated with an oral regimen of atovaquone-proguanil; the repeat blood smear was negative. None of the four military patients with severe malaria was reported to have died from this illness.Among military patients in the United States, four received a diagnosis of severe malaria; all had traveled to Africa and were infected with Among U.S. residents (civilian and military), information about malaria chemoprophylaxis use was reported for 1,157 (88.5%) of 1,308 imported cases; among these patients, 829 (71.7%) indicated that no chemoprophylaxis medication was taken during travel. Among the 328 patients who reported taking chemoprophylaxis, 115 (35.1%) did not indicate which medication was taken. Among 213 patients who reported specific drug information, 180 (84.5%) took a regimen recommended by CDC for the region of travel. Among 157 reports containing self-reported adherence information, 90 (57.3%) patients reported missing doses. Of the 90 U.S. residents with malaria who initiated an appropriate chemoprophylaxis regimen but did not adhere to it entirely, 75 (83.3%) persons provided reasons for missing doses, which included prematurely stopping after leaving the area where malaria was endemic (30.7%), forgetting to take the medication (28.0%), stopping because of a side effect (12.0%), and stopping because they didn’t think it was needed (12.0%); unknown and other reasons  also were reported, although less frequently. Although not formally asked about on the malaria case report form, 12% of respondents answered that they stopped prophylaxis because of a prescription error or running out of the medication. Of the nine persons who reported stopping prophylaxis because of side effects, eight took doxycycline; of those, four persons reported gastrointestinal side effects, one person reported discoloration of the skin, one reported nightmares and depression, and two did not specify a side effect. In addition, one patient who took atovaquone-proguanil for prevention stopped because of symptoms of fatigue. Among patients who took chemoprophylaxis, reported adherence was comparable in 2017 to adherence in 2016 (67 [42.7%] of 157 in 2017 versus 58 [43.9%] of 132 in 2016). Among 180 patients who took CDC-recommended chemoprophylaxis, 68 (37.8%) took doxycycline, 58 (32.2%) took mefloquine, 45 (25.0%) took atovaquone-proguanil, three (1.7%) took chloroquine, and six (3.3%) took two or more CDC-recommended medications. Of the 717 U.S. residents classified as VFR travelers and for whom information on chemoprophylaxis use was available, 173 (24.1%) took any prophylaxis, which was lower than among non-VFR travelers (155 [35.2%]). In addition, a lower proportion of VFR travelers (30 [4.8%] of 622) reported completing the regimen of chemoprophylaxis compared with non-VFR travelers (37 [9.9%] of 373). Altogether, among the 995 U.S. resident cases with complete information on chemoprophylaxis, 67 (6.7%) patients were adherent to an appropriate regimen, 838 (84.2%) patients did not take chemoprophylaxis or took an incorrect regimen, and 90 (9.1%) patients took an appropriate regimen but reported incomplete adherence. Thus, 93% (928 of 995) of U.S. residents with malaria either did not take or did not adhere to a CDC-recommended chemoprophylaxis regimen.P. vivax accounted for 14 (8.6%) and P. ovale for 15 (9.3%) of these cases. Primary prophylaxis can prevent acute illness in P. vivax and P. ovale infections, although the patient might experience a relapsing illness unless primaquine is taken to eliminate dormant hypnozoites   of 180 patients who took a CDC-recommended chemoprophylaxis regimen; Plasmodium species who reported taking a CDC-recommended prophylaxis regimen, 122 (75.3%) of the infections were from P. falciparum, and 10 (6.2%) were from P. malariae. Among the patients with P. falciparum infections, 120 (98.4%) reported travel to Africa, and 74 (60.7%) of these had traveled to West Africa; two P. falciparum cases occurred after travel to the Caribbean (one each to Haiti and the Dominican Republic). Of 108 P. falciparum case reports containing information on adherence to the recommended prophylaxis regimen, 66 (61.1%) patients were not adherent. A total of 42 cases of P. falciparum occurred among patients who reported complete adherence to a recommended chemoprophylaxis regimen; 16 (38.1%) patients took mefloquine, 15 (35.7%) took doxycycline, and 11 (26.2%) took atovaquone-proguanil. All 42 patients with P. falciparum infections who adhered to chemoprophylaxis acquired their infections from Africa, with 26 (61.9%) from the West Africa region. Of the 16 infections acquired by patients who adhered to mefloquine, nine were from West Africa, three were from Kenya, two were from Cameroon, and one each was from Equatorial Guinea and Uganda. Of the 15 infections acquired among patients who adhered to the doxycycline regimen, nine were from West Africa. Of the 11 patients with malaria who adhered to atovaquone-proguanil for chemoprophylaxis, eight cases were acquired from West Africa, and one case each was acquired from Cameroon, Uganda, and Africa, country unspecified. CDC received three specimens for molecular resistance surveillance from patients with these infections who adhered to chemoprophylaxis; two patients took mefloquine and one took doxycycline for chemoprophylaxis. Of the two who reported adherence to mefloquine for prophylaxis, both had been to Kenya for short-term travel ; one person traveled for tourism, and one did not specify a reason for travel. Of two samples tested, one had a pfmdr1 copy number amplification, which is known to be associated with mefloquine resistance. Valid genetic markers are not available to assess one specimen from a person who took doxycycline for chemoprophylaxis. No specimens from the patients who adhered to atovaquone-proguanil were provided for molecular resistance testing.Among the 162 patients with identified P. malariae occurred after patients had taken a recommended prophylaxis regimen. All 10 patients had information on adherence; five patients reported taking all doses of chemoprophylaxis, and five did not adhere to the regimen. Of the five patients who were adherent to chemoprophylaxis, two took atovaquone-proguanil, two took mefloquine, and one took doxycycline. All five had traveled to African countries outside of West Africa . Specimens were not tested at CDC for any of the patients who reported adherence. Possible explanations for Plasmodium infections in patients who adhered to chemoprophylaxis include inadequate dosing or malabsorption of the chemoprophylaxis medication, inaccurate reporting of adherence, emerging parasite resistance, or chemoprophylaxis failure.A total of 10 cases of P. falciparum, 15 (33.3%) recalled P. vivax, five (11.1%) recalled P. malariae, and one (2.2%) recalled P. ovale. Of the 16 patients who recalled having a previous P. vivax or P. ovale infection, all were currently infected with the same species and were likely relapses. Among the 16 likely P. vivax or P. ovale relapses, six patients reported complete dates for the current and former illness onsets, and the mean number of days between the previous and relapsing illness was 135 days (minimum of 54 and maximum of 258 days). Of 16 patients who recalled having a previous P. vivax or P. ovale infection, 15 provided information on the country of acquisition for the current infection; eight infections were acquired from Asia, four from South America, two from Africa, and one from Oceania. Of 16 patients with P. vivax or P. ovale infections, five had documentation of receiving primaquine for the current illness to prevent relapse. In one case, an immigrant arriving in the United States from India in 2016 had three P. vivax illnesses in 2017, occurring in February, April, and August. The April and August illnesses were classified as relapses. Treatment medications were not reported for this patient’s first two illnesses; however, primaquine, to prevent relapses, was documented for treatment of the August (third) illness, and the patient recovered.Among the 2,112 cases of malaria imported into the United States in 2017, reports for 1,488 (70.5%) provided information on previous history of malaria; 302 (20.3%) reported having had malaria during the past 12 months. The infecting species for the previous illness was reported for 45 (14.9%) of 302 patients with a previous history of malaria; 24 (53.3%) recalled P. falciparum infection during the past 12 months, 16 (66.7%) had a current infection with P. falciparum, four (16.7%) had P. ovale, two (8.3%) had P. vivax, and one (4.2%) each had P. malariae or an unknown species reported for the current infection. Among the five patients who recalled a previous P. malariae infection during the past 12 months, four (80.0%) were currently infected with P. malariae, and one (20.0%) was infected with P. vivax. The species recall for the previous infections were not validated; therefore, a larger number of patients might have experienced a relapse, especially those who were currently infected with P. ovale or P. vivax . Of 29 persons who recalled having a previous infection with P. falciparum or P. malariae, 28 had information on the country of acquisition for the current infection; 23 (82.1%) acquired their current infection from Africa, three (10.7%) from Asia, and two (7.1%) from South America. Persons who were infected with nonrelapsing species  could have been infected again during the past 12 months while they were in a country where malaria is endemic. Of these 29 patients, four had illnesses reported in the United States earlier in 2017 or in 2016; the other patients might have had earlier illnesses while outside of the United States, or, if a patient experienced an earlier malaria illness within the United States, then the available information might not have been sufficient to match the patient to the same person.Among the 24 patients who recalled a Among nonmilitary U.S. residents , the reason for travel to a country where malaria is endemic was reported for 1,038 (81.0%) of 1,282 imported malaria cases . Of thesAmong the 515 imported cases among non-U.S. residents, reason for travel was available for 409 (79.4%) cases . Among tP. falciparum, and one each were P. vivax, P. ovale, and P. malariae. Among children, three cases were severe, and no deaths were reported.Age was reported for all 2,161 (100%) of the patients with malaria in 2017, and of these, adults aged ≥18 years accounted for 1,781 (82.4%) cases. Among adult malaria cases, one was transfusion induced and two cases were cryptic. A total of 67 (3.1%) patients were aged <5 years, and 146 (6.8%) were aged ≥65 years. Of the 380 (17.6%) children (aged <18 years), 150 (39.5%) were U.S. residents, and 134 (89.3%) of these had traveled to Africa. Among the U.S. resident children, 146 cases were imported, two were congenital, one was transfusion induced, and one was cryptic. Of the 146 imported cases among U.S. resident children aged <18 years, 102 (69.9%) were VFR travelers, nine (6.2%) traveled for education, five (3.4%) traveled for tourism, and three (2.1%) traveled as a dependent for missionary or religious purposes. Travel for volunteer humanitarian reasons was reported for one child, and no reason was provided for 26 children. Among these 146 children, information on chemoprophylaxis use was provided for 134 (89.3%); 82 (61.2%) did not take medication during travel to prevent malaria. Of the 52 (38.8%) children who took a chemoprophylaxis regimen, 31 (59.6%) took a CDC-recommended antimalarial that was appropriate for the region of travel, 19 (36.5%) did not report the regimen taken, and two took an incorrect medication for the country of travel. Of 98 children who were VFR travelers, 40 (40.8%) took any chemoprophylaxis medication, whereas 12 (33.3%) of 36 non-VFR travelers aged <18 years took any chemoprophylaxis. Of the 28 children with information on adherence, case reports from 12 (42.9%) indicated that all doses were taken; nine (75.0%) of 12 children who adhered were VFR travelers. Of 12 cases in children who adhered to prophylaxis, 11 cases were acquired from Africa, and one was acquired from Asia; nine of these cases were confirmed P. falciparum, P. ovale, and P. malariae species by PCR. The child was treated with atovaquone-proguanil.An asymptomatic child aged 7 years who immigrated to the United States from the Democratic Republic of Congo was tested as part of an adoption screening process and was infected with multiple species. The CDC reference laboratory confirmed infection with Hispanic or Latino ethnicity information was provided for 1,793 (83.0%) of 2,161 cases. A total of 35 persons reported Hispanic or Latino ethnicity; 19 (54.3%) infections were acquired from Africa, seven (20.0%) from Central America or the Caribbean, six (17.1%) from South America, one (2.9%) from Asia, and two (5.7%) from an unknown region. Of the patients reported as having Hispanic or Latino ethnicity, 22 were U.S. residents, 12 were non-U.S. residents, and one did not have residence status reported.Race information was available for 1,884 (87.2%) cases; of these, 1,480 (78.6%) cases were Black or African American, 265 (14.1%) were White, 129 (6.9%) were Asian, and <1.0% were American Indian/Alaskan Native or Hawaiian/Pacific Islander. Of the 1,290 U.S. residents, information on race was available for 1,173 (90.9%). Of these, 910 (77.6%) were Black or African American, 213 (18.2%) were White, 45 were Asian, and <1.0% were other races. Of the 707 U.S. residents with race information and who had traveled to visit friends and relatives, 666 (94.2%) were Black or African American, 21 (2.8%) were White, and 19 (2.7%) were Asian; <1.0% were other races.Among all cases with race information in 2017, of the 1,480 Black or African American patients, 1,403 (94.8%) had traveled to Africa. Of the 129 cases among Asian patients, 106 (82.2%) had traveled to Asia, and 17 (13.2%) had traveled to Africa. Persons who were reported as White (265 cases) predominantly traveled to Africa (214 [80.8%]); 5.3% of White patients had traveled to South America (14 cases), 4.9% to Asia (13 cases), and 3.8% to Central America and the Caribbean (10 cases).P. falciparum malaria in 2017, and 278 (21.4%) hospitalized patients had one or more signs or symptoms of severe malaria. No significant change in these percentages occurred from 2016 to 2017; in 2016, a total of 1,261 [68.9%] patients were hospitalized among 1,831 with this information reported, 918 (72.8%) with P. falciparum and 268 (21.3%) with severe malaria .In 2017, hospitalization information was reported for 1,904 (88.1%) of 2,161 confirmed cases; of these, 1,302 (68.4%) patients were hospitalized for their malaria illness. A total of 972 (74.7%) hospitalized patients had Among the 2,161 confirmed malaria cases in 2017, a total of 1,849 (85.6%) cases were uncomplicated. Of these, 1,567 (84.8%) had antimalarial treatment information indicated on the case report form. The most common treatment administered for uncomplicated malaria in 2017 was atovaquone-proguanil, used to treat 966 (61.7%) patients with treatment information, an increase from 2016 when 879 (58.1%) atovaquone-proguanil treatments were reported. Quinine-based treatment was the second most common; 237 (15.1%) patients were treated with this regimen. Artemether-lumefantrine, the only artemisinin-based combination therapy approved by FDA for treatment of uncomplicated malaria in the United States, was used for 200 (12.8%) patients. A total of 111 (7.1%) uncomplicated cases were treated with chloroquine, and 82 (5.2%) were treated with mefloquine.CDC Guidelines for Treatment of Malaria in the United States, herein referred to as the CDC guidelines, provides guidance for the treatment of malaria according to species, disease severity, pregnancy status, and region of acquisition  were treated according to CDC guidelines, and 125 (12.9%) of these patients received an antimalarial treatment that exceeded the recommendations. Of 100 P. falciparum patients who were not treated in accordance with CDC recommendations, three (3.0%) were pregnant. Treatment followed CDC guidelines for 36 (92.3%) of 39 cases of uncomplicated P. malariae infections; nine (25.0%) of those patients received an additional antimalarial medication. Of those with P. ovale and P. vivax infections, 91 (89.2%) and 153 (86.9%), respectively, were treated in accordance with CDC guidelines for their acute infection; one (1.1%) patient with a P. ovale infection and 12 (7.8%) patients with P. vivax infections received an additional acute-phase antimalarial medication. Administration of primaquine to treat relapsing illness (the liver hypnozoite stage of the parasite) was reported for 68 (39.3%) of all 173 nonpregnant patients with P. vivax infections and treatment information. Among the 101 nonpregnant patients with P. ovale infections, primaquine was administered to 23 (22.8%). Of 16 mixed infections with recorded treatment information, 13 (81.3%) were treated according to CDC guidelines; seven (53.9%) of these patients received an additional antimalarial to treat the acute illness. Malaria infections with an unknown species should be treated following recommendations for P. falciparum  had P. vivax infections, and 10 (3.2%) were infected with an unknown Plasmodium species. Less than 1.0% of severe infections were caused by P. malariae (n = 2), P. ovale (n = 2), or mixed species (n = 1). In 2017, the species distribution among severe cases was similar to the distribution in 2016. All six patients who died of severe malaria in 2017 had P. falciparum infections.In 2017, a total of 312 (14.4%) of 2,161 cases were classified as severe malaria. Of the patients with severe malaria, six (1.9%) died. One patient who died, for a total of seven deaths, was considered to have had uncomplicated malaria and died from other causes. Among severe cases, 242 (77.6%) occurred in adults aged 18–64 years. However, children <18 years were more likely to have severe malaria than adults . The proportion of adults aged ≥65 years with severe malaria was 16.4% (24 of 146 cases); the proportion of severe malaria among patients aged <65 years was 14.3% . In 2017, a similar proportion of patients with severe malaria were U.S residents or non-U.S. residents; 208 (15.8%) of 1,316 U.S. residents, compared with 67 (13.0%) of 516 non-U.S. residents, had severe malaria. Among patients with severe malaria in 2017, a total of 285 (91.4%) had Among 207 U.S. residents with imported severe malaria and information on chemoprophylaxis (66.3% of 312 severe cases), 44 (18.6%) reported having taken any medication for chemoprophylaxis; 18 (40.9%) of these did not provide adherence or chemoprophylaxis medication information. Among 26 patients with severe malaria and known chemoprophylaxis adherence information, 69.2% (18 cases) did not adhere to or take a recommended regimen for malaria prevention, compared with 60.4% (90 of 149) of persons (U.S. residents and imported cases) with uncomplicated malaria who did not adhere to chemoprophylaxis or take the correct regimen. Of the eight patients with severe malaria who adhered to a recommended chemoprophylaxis regimen, three each took atovaquone-proguanil or doxycycline, and two patients took mefloquine. One specimen from a patient who took doxycycline was tested at CDC, although no validated markers for doxycycline resistance are known. Potential reasons for chemoprophylaxis failure in these patients with severe malaria include inadequate dosing or malabsorption of the chemoprophylaxis medication, inaccurate reporting of adherence, or emerging parasite resistance.Plasmodium species parasitemia, of which 176 (68.8%) had ≥5% parasitized red blood cells. CDC guidelines in 2017 stated that patients with severe malaria should be treated aggressively in an inpatient setting with intravenous quinidine gluconate or artesunate. In 2017, a total of 24 (7.7%) patients with severe malaria were not hospitalized; the hospitalization status for another 10 (3.2%) patients was unknown. At that time, the only FDA-approved medication for this indication was intravenous quinidine gluconate; for patients who could not tolerate quinidine gluconate or when quinidine was not available, artesunate could be obtained from CDC through an investigational new drug protocol  patients. Cerebral malaria was reported for 33 (10.6%) patients, acute respiratory distress syndrome for 25 (8.0%), severe anemia for 13 (4.2%), and jaundice for 12 (3.9%). Case reports from 256 patients with severe malaria contained information on the percentage of Plasmodium species can cause severe malaria, the rapid proliferation of P. falciparum parasites requires timely diagnosis and treatment to prevent progression to hyperparasitemia and severe illness. In 2017, on average, inpatients with P. falciparum infections were hospitalized 5.2 days after illness onset, regardless of disease severity .In 2017, a total of 168 (55.1%) of 305 patients with severe malaria and information on treatments received appropriate treatment, a comparable proportion to 2016, when 147 (49.7%) of 296 patients received appropriate treatment. In 2017, patients with severe malaria were significantly more likely to have inappropriate treatment (137 [44.9%] of 305) than patients with uncomplicated malaria . Although all malaria Among the 312 patients with severe illness, 293 (93.9%) infections were acquired from Africa; 11 (3.5%) from Asia; and <1.0% from the Caribbean (three cases), South America (two cases), and Central America (one case). Infection from an unknown region was acquired by two patients with severe malaria. Among the 258 (82.7%) patients with severe malaria who reported a reason for travel, 142 (55.0%) reported VFR as the primary reason for travel, of whom 134 (94.4%) had acquired the infections from Africa, and 99 (69.7%) of these were from West Africa. A total of 26 (10.1%) patients with severe illness traveled for business, and 23 (8.9%) each traveled for tourism or for missionary or religious purposes. Of patients with severe malaria, 22 (8.5%) traveled to the United States as immigrants or refugees, and 15 patients (5.8%) traveled for education (as a student or teacher). Less than 1.0% of patients with severe cases traveled as members of the U.S. military (three cases), as crew of an airline or ship (one case), or for another reason (three cases).Among 805 women with malaria diagnosed in the United States in 2017, a total of 27 (3.4%) were pregnant, a decrease from 2016 when 50 (6.3%) women with malaria were pregnant. In 2017, a total of 22 (81.5%) pregnant women were hospitalized, including all four (14.8%) with severe malaria; all pregnant women with malaria recovered. Data on birth outcomes are not systematically collected.P. falciparum infections, three (11.1%) were infected with P. vivax, one (3.7%) with P. ovale, and three with an unspecified Plasmodium species. Approximately half of the pregnant women (14 [51.9%]) were non-U.S. residents, and 10 (37.0%) were U.S. residents; residency status was not provided for three (11.1%) women. Of 20 (74.1%) pregnant women who indicated a reason for travel, 10 (50.0%) were refugees or immigrants, nine (45.0%) traveled to visit friends and relatives, and one (5.0%) traveled for business.Among pregnant women, 20 (74.1%) had Due to the safety profile of medications approved for pregnancy and antimalarial resistance patterns, antimalarial drug choices to prevent or treat malaria during pregnancy are limited. In most areas where malaria is endemic, only mefloquine is approved for chemoprophylaxis; in 2017, either mefloquine or quinine with clindamycin was recommended as treatment for uncomplicated malaria during pregnancy  were treated in accordance with CDC guidelines, which is a similar proportion to nonpregnant women (75.9%) who were treated according to guidelines. Among the six pregnant women whose treatment was not in accordance with CDC guidelines, two patients received atovaquone-proguanil, which is not recommended for use during pregnancy; one woman was treated with a chloroquine-based regimen, which was not appropriate for the region of travel; and one woman with uncomplicated malaria was treated with artemether-lumefantrine, which at the time of treatment in 2017 was not recommended for use in pregnant women but subsequently became endorsed for use in pregnant women in 2018  of 117 specimens tested for antimalarial resistance (pfk13 mutations associated with resistance (CDC received 143 (6.6%) whole blood samples for analysis of molecular markers of resistance from patients who received a malaria diagnosis in 2017. Of these, 19 samples were from patients who did not have sistance . Of the sistance .pfmdr1 gene) had traveled to Kenya, Ghana, and Nigeria. Of these three, one reported taking mefloquine for chemoprophylaxis and reported complete adherence, suggesting that the illness could have been sustained because of the parasites’ resistance to mefloquine. No patients with the mefloquine-resistant genotype were treated with mefloquine, and all recovered from their illness. Information on travel, chemoprophylaxis, and treatment medications was available for two of the three patients who acquired malaria with genetic markers for atovaquone resistance. They had traveled to Ghana and Guinea and did not report having taken chemoprophylaxis. Of these two patients, one was treated with artemether-lumefantrine and one with atovaquone-proguanil. For the patient who had traveled to Guinea and was treated with atovaquone-proguanil, no treatment failure was indicated.Because of widespread resistance to pyrimethamine and sulfadoxine, CDC does not recommend using drugs containing these components to treat malaria in the United States ; however, because clinicians believed atovaquone-proguanil prompted her to have hypoglycemia, her treatment was changed to quinine PO and doxycycline PO. Primaquine PO was administered, and the patient was advised to pump and dispose of her breast milk for 18 days. One day after birth, a full-term female infant that weighed 5 lb, 12 oz, at birth was tested for malaria using a blood smear, and no parasites were detected. Approximately 4 weeks after birth, the infant experienced fever and had symptoms of anemia and thrombocytopenia. Blood smear showed P. vivax with 5% parasitemia. The infant was admitted to the perinatal intensive care unit and administered hydroxychloroquine PO via feeding tube, intravenous (IV) clindamycin, and IV quinidine and monitored for cardiac arrythmias. After completion of quinidine, the infant was transferred from the perinatal intensive care unit to the pediatric inpatient ward, where she completed a 7-day course of IV clindamycin without cardiac monitoring. Repeat laboratory tests showed resolution of parasitemia and improvement in anemia and thrombocytopenia, and the infant was discharged after 8 days in the hospital.Case 2. An Asian male infant aged 18 days, born full-term, whose mother was asymptomatic and had immigrated to the United States from Pakistan 1 year earlier, developed a rash on his abdomen and chin. His primary care physician diagnosed staph pustulosis and discharged him. That night he developed a fever of 103°F (39.4°C) and did not wake to eat. The next morning, he was returned to the primary care physician, where he was febrile and referred to the emergency department. Laboratory results showed elevated liver enzymes  and blood urea nitrogen, and thrombocytopenia. Blood smear identified P. vivax parasites with <5% parasitemia. The infant was administered chloroquine PO in the hospital and IV antibiotics, including clindamycin, for the staph skin infection. The mother was counseled to obtain treatment for malaria with chloroquine and primaquine, although she has no record of a malaria diagnosis. The infant was discharged from the hospital after 4 days.In 2017, two cases of TTM occurred through blood transfusions in the United States.Recipient 1. A report of this case and investigation was published , were available for testing. All eight donors were contacted to request a follow-up blood sample, of whom five provided a sample months after the initial donation. Altogether, seven of eight donors had specimens that were evaluated. Of the six donors’ specimens tested by immunofluorescence assay (IFA) for the presence of malaria antibodies, five were negative for all Plasmodium species tested. Five of six donors’ specimens tested by PCR  had only negative results. The sole donor who had specimens test positive (by IFA and PCR) had a red blood cell segment sample and a fresh blood sample available for testing. The segment sample was positive by IFA for P. falciparum at a titer of 1:64 and had an RT-PCR cycle threshold value of 40.9 for P. falciparum, which is at the limit of detection. The follow-up whole blood sample was positive for P. falciparum by IFA at a dilution titer of 1:1,024. PCR was conducted four times on the whole blood sample from this donor (RT-PCR three times and nested PCR one time), and P. falciparum parasites were detected in one of four PCR tests. Because the donor specimen had low parasite density, performing extensive molecular genotyping to match the parasites between the recipient and donor was not possible. However, genetic marker analysis of merozoite surface protein 1 and merozoite surface protein2 showed loci amplicon sizes of approximately 180 and 300 base pairs, respectively, for both the recipient and donor specimens.Donor 1. The implicated donor in this case of TTM was an asymptomatic, first-time donor, born in West Africa. The donor questionnaire, which was completed in early 2017 at the time of the blood donation, showed that the donor denied being outside of the United States or Canada during the previous 3 years or ever having malaria. During the investigation, another interview determined that the donor had immigrated from West Africa in mid-2014 and had experienced previous episodes of malaria at unknown times. The donor was treated with atovaquone-proguanil PO for uncomplicated malaria.Recipient 2. At the end of 2016, a White male child aged 14 months was admitted for respiratory failure that required extracorporeal membrane oxygenation (ECMO) for 22 days in early 2017 and transfusion with 48 units of packed red blood cells. Approximately 1 month after the start of ECMO, the patient developed fever and was treated with multiple antibiotics, and while the blood cultures remained negative, fevers continued. The patient did not travel outside of his home state. Non-P. falciparum parasites were identified on thin and thick blood smears 1 week after fever onset. PCR was used to confirm infection with P. ovale. The patient was treated with chloroquine PO and primaquine PO and recovered.Investigation 2. The blood center identified 27 donors who contributed 48 units of packed red blood cells to the recipient in early 2017. All 27 donors were interviewed again by the blood center. Three donors were foreign-born , and follow-up blood specimens were requested and obtained from the donors from Cameroon and Iran. The donor from Cameroon was considered highest risk because of travel within the last 3 years. IFA and PCR tests were negative for the donor originating from Iran. A specimen from the donor originally from Cameroon tested positive by IFA for P. falciparum and P. ovale . Whole blood from the Cameroonian donor was negative by PCR . No other donor specimens were tested in this investigation.Donor 2. The limited testing performed in this investigation suggests that the recipient’s malaria infection could have originated from the blood donor who had been in Cameroon within the previous 3 years. No additional details about the donor were provided to CDC by the blood center or health department. Whether the implicated donor was referred for antimalarial treatment is unclear.Three cases were classified as cryptic in 2017. The patients had not traveled recently, and investigations revealed a low likelihood of local transmission and no health care or blood exposure .Case 1. Twelve days after the onset of unspecified symptoms, a Black male aged 16 years went to the emergency department and was admitted the following day with a febrile illness. The public health laboratory and CDC confirmed that the patient had a P. falciparum infection with 2% parasitemia. He was treated with atovaquone-proguanil PO and recovered. The patient was born in the United States, but his parents were from Nigeria and they spent substantial time there. In repeated interviews with health care providers and the local health department, the patient and his guardian reported that the last time he had traveled internationally was to Nigeria, more than 2 years earlier, in 2015, for approximately 15 days; he had never lived in Nigeria or another country where malaria is endemic. The patient stated that he had never had malaria, nor did he have a febrile illness after travel. However, the patient’s father was treated for malaria in Nigeria 1 or 2 years previously and had also received a malaria diagnosis in the United States in 2016, confirmed by the state public health laboratory. Blood specimens for the father (2016 illness) and son (2017 illness) were sent to CDC, and parasite sequencing and microsatellite analysis was conducted. Genotype profiles and microsatellite results showed that the parasites from the father’s 2016 illness and the son’s 2017 illness were not related. The patient traveled to a southern U.S. state 1 month before illness onset, although his infection could not be linked epidemiologically to any malaria case there. The local health department vector control staff conducted mosquito surveillance in the vicinity of the patient’s residence weekly during the month of his 2017 illness and did not find Anopheles species mosquitos, which are the type of mosquitos that transmit malaria. Although Anopheles quadrimaculatus is present in the region, mosquito surveillance in this county found only two specimens in 2017; both were located outside of city limits and far from the patient’s residence. The health department did not find evidence of local transmission.Case 2. A Black woman aged 23 years had emigrated from the Democratic Republic of Congo to a refugee camp in Tanzania at age 3 years, where she lived until she immigrated to the United States at age 13 years during 2007, which was the last time she reported traveling. Recently, Schistosoma mansoni eggs had been identified in her stool, and she was treated with praziquantel; she had splenomegaly, leading to a laparoscopic splenectomy. She sought care at the emergency department 3 days after discharge from the hospital for the splenectomy, which had occurred 1 week previously; she had fever (102.9°F [39.4°C]) and a bifrontal headache that resolved between fevers. The patient was admitted for additional evaluation and management. An infectious disease consult was ordered. Laboratory analysis indicated she was anemic  and lymphopenic (3.1% of white blood cells). A chest radiograph and abdominal computerized tomography (CT) scan did not show any abnormalities. She received a malaria diagnosis by blood smear, and PCR at a commercial laboratory confirmed P. ovale species; no parasitemia was reported. Primaquine PO was the only antimalarial medication documented in the medical record. Possible explanations for this illness include delayed relapse that opportunistically appeared after splenectomy and nondisclosed travel.Case 3. An Asian man aged 71 years was admitted to the hospital and received a diagnosis by blood smear microscopy and PCR , confirming P. malariae infection with 2% parasitemia. He was treated with chloroquine PO and recovered. The state health department interviewed the patient in Mandarin two times. The patient immigrated to the United States from Hong Kong several years earlier, with the last travel there 4 years previously. The patient reported having chronic malaria and symptoms for 8 years. The patient had a history of leukemia and was receiving chemotherapy. The patient was asked about travel to mainland China and other Asian countries, which he stated had not occurred. He did not have a history of blood transfusion or organ transplantation. His medical chart was reviewed, and no additional information was found. Rarely, P. malariae parasitemia has been documented to persist for years after initial infection  around 8 p.m. with worsening confusion and weakness, which rapidly progressed to lethargy and respiratory failure. The patient reported no fever or bleeding. He experienced septic shock and received intubation to protect his airway along with mechanical ventilation. Treatment included broad-spectrum antibiotics. At approximately 1:30 p.m. the following day, the clinical staff were notified that the patient had a Plasmodium species infection; no species or percent parasitemia were reported at this time. Antimalarial medication, including intravenous quinidine, was ordered and administered at 6:25 p.m. on the second day in the ICU. While hospitalized, the patient experienced hemolytic anemia (with an Hb decrease from 11 g/dL to 7.9 g/dL), acute respiratory distress syndrome, acute kidney injury, acidosis, thrombocytopenia, and multiorgan failure. His family refused blood product transfusion on his behalf because of religious reasons. During the evening of the second day of his admission, he suffered a cardiac arrest, and cardiopulmonary resuscitation was not attempted per family wishes. The patient died at 9:55 p.m. on the second day in the ICU. Four days after his death, the final laboratory report showed P. falciparum infection with 90% parasitemia, although this result was not externally validated by a reference laboratory.Case 3. A White man aged 50 years traveled to Burkina Faso for 10 days in November 2017 on a mission trip and did not take malaria prophylaxis. A few weeks after returning, he experienced fever and fatigue but did not seek medical attention. A week after the start of his symptoms, his daughter found him at home with altered mental status and a bruise on his forehead. She took him to an emergency department, where the workup revealed acute kidney injury, jaundice, and a positive malaria smear, with no species or parasitemia reported. A CT scan of the head showed no abnormalities. The patient was administered intravenous clindamycin and early the following day was transferred to another hospital, where he was admitted to the ICU and was given IV quinidine gluconate and IV doxycycline for treatment of severe malaria. Shortly after starting quinidine, a widened QRS complex was observed on an electrocardiogram, and quinidine toxicity was suspected. IV artesunate was requested from CDC and administered. However, the patient’s condition deteriorated, requiring intubation and mechanical ventilation, vasopressor support, and continuous renal replacement therapy for acute kidney injury. The patient died on the eighth day after being hospitalized. The malaria smear at the initial hospital was sent to an outside laboratory, and results available later revealed P. falciparum infection with 16% parasitemia.Case 4. A White man aged 76 years with a history of lymphoma, autoimmune hemolytic anemia, diabetes, and chronic kidney disease traveled to Cameroon for 1 month with unknown adherence to atovaquone-proguanil prophylaxis. He experienced fever 6 days after returning. He sought medical care on day 12 of the fever, received a diagnosis of possible uncomplicated malaria, was prescribed oral doxycycline for possible tickborne infection, and was discharged home. Malaria smears were sent to an outside laboratory, and results were available 3 days later, indicating P. ovale infection with 0.02% parasitemia. Although PCR was conducted, speciation was unsuccessful, and the result was documented as “Plasmodium present.” After receiving these results, the health care providers attempted to contact the patient with the results of the test so that he could begin treatment with appropriate antimalarials. He was found that same day unresponsive at his home and was brought to the emergency department. He was admitted to the ICU, received intubation and mechanical ventilation for acute respiratory failure, was administered vasopressors for hypotension, and experienced both renal failure and acidosis. The patient received intravenous doxycycline and quinine, administered by nasogastric tube. The patient died 1 day later. Because of the very low parasite load, cause of death was believed to be due to cardiogenic factors, unrelated to malaria. After a review of the medical records, this patient was classified as having uncomplicated malaria.Case 5. A Black woman aged 56 years had traveled to Nigeria; whether she took chemoprophylaxis to prevent malaria is unknown. Approximately 3 weeks after returning to the United States, she was admitted to the hospital for fever and altered mental status, and she left against medical advice. A few days after being home, where she lived alone, she experienced bilateral lower extremity weakness and spent 4 days on the floor of her bedroom and kitchen, until a family member found her. Emergency medical services were called, and the patient was transport to a hospital  by ambulance at 2:40 p.m. The patient had a history of hypertension, non–insulin-dependent diabetes mellitus, and morbid obesity. The emergency department workup showed that she had jaundice, sepsis, generalized weakness, acidosis, anemia, thrombocytopenia, and acute kidney injury. The woman was admitted and treated for severe lactic acidosis caused by sepsis and liver failure. Treatment included continuous renal replacement therapy, fluids, antibiotics, and vasopressors. At 11:18 a.m. the following day, the pathologist informed the clinical team that abnormal ring form inclusions were identified in red blood cells, compatible with Babesia or Plasmodium species. While the final diagnosis was being confirmed, the team decided to treat the patient for severe malaria, and IV quinidine was administered on her second day of treatment. Approximately 1 hour after starting the quinidine, the patient had hypotension, worsening acidosis, and an increased need for vasopressors. She also experienced obtundation and agonal breathing and received intubation and mechanical ventilation. The woman then experienced cardiac arrest, and attempts to resuscitate her were unsuccessful. She died the day after she was admitted to the hospital. Subsequent PCR testing confirmed that she was infected with P. falciparum.Case 6. A Black man aged 44 years traveled to Nigeria for 3 weeks to visit family and friends and did not take chemoprophylaxis to prevent malaria. Two days after his return to the United States, he experienced symptoms including fever, headaches, body aches, dizziness, vomiting, and dark urine. He sought care 6 days later and received a diagnosis of severe P. falciparum malaria with multisystem organ failure. The patient initially was treated with IV quinidine, intubation with mechanical ventilation, and vasopressors. He received multiple blood transfusions and hemodialysis. Because of QT prolongation, quinidine was replaced with artesunate. The percent parasitemia dropped from 10% to undetectable with treatment; however, the patient remained critically ill and experienced multisystem organ failure. On hospital days 4 and 5, he experienced three cardiac arrests. Attempts at resuscitation after the third arrest were unsuccessful, and the patient died.Case 7. A White man aged 78 years traveled for 2 weeks to Tanzania to visit friends and relatives. No chemoprophylaxis was taken to prevent malaria. The patient developed symptoms the day he returned to the United States. He was admitted to the hospital and received a diagnosis of P. falciparum malaria by blood smear and RDT, with 33% parasitemia. The patient had cerebral malaria and was treated with IV quinidine, quinine PO, doxycycline (route unknown), and atovaquone-proguanil PO. The patient died 4 days after symptom onset. Limited additional details are available for this case because the medical record was not provided for review.P. falciparum infections, which cause the most severe disease and greatest risk for death, account for 70% of all imported cases in the United States. Malaria occurring among U.S. civilians accounts for the increase in cases over the last four and a half decades.The number of persons who received a malaria diagnosis in the United States has been increasing since the mid-1970s, with the highest number of cases since 1971 reported in 2016  and 2017  . Two thiAntimalarial chemoprophylaxis medications are effective at preventing malaria, and adhering to an appropriate chemoprophylaxis regimen is the best way for travelers to prevent this potentially life-threatening illness. Among U.S. civilians, those traveling to visit friends and relatives are the most common group to acquire malaria, and they are less likely than other types of travelers to have taken any chemoprophylaxis . Although pretravel health consultations are necessary to obtain prescription antimalarial medications tailored for the person’s age, pregnancy status, destination country, preferences , tolerability of potential side effects , and cost, many travelers do not seek pretravel consultations . Health insurance policies often do not provide coverage for potentially life-saving antimalarial chemoprophylaxis medications , then a weekly dose while traveling in the area where malaria is endemic (200 mg/week), followed by a single dose (200 mg) during the week after departing the malaria transmission area. The most common side effects are gastrointestinal disturbances, dizziness, and headache (https://www.fda.gov/safety/medwatch-fda-safety-information-and-adverse-event-reporting-program).In 2018, FDA approved tafenoquine (Arakoda) for malaria chemoprophylaxis in nonpregnant persons aged ≥18 years who are not G6PD deficient as confirmed by a quantitative G6PD test (https://www.cdc.gov/dpdx/training.html). The CDC Malaria Hotline provides assistance to health care providers diagnosing suspected or confirmed malaria and treating patients. To speak with the person on call for malaria consultations, call 770-488-7788 or toll-free 855-856-4713 during regular business hours, or CDC’s Emergency Operations Center at 770-488-7100 during evenings, weekends, and holidays. Additional information is available at the CDC website .To prevent severe disease or death, improve prognosis, and prevent extended (and expensive) hospitalizations , CDC and public health officials have investigated potential cryptic malaria cases among patients who did not disclose a complete or accurate travel history . For most of the potential cryptic cases, nondisclosed travel was discovered ; sometimes a passport review or an inquiry into official travel records can be helpful to identify nondisclosed travel.Plasmodium species, the percent parasitemia, and the patient’s pregnancy and clinical status , and 25.9% of all pregnant women received treatment inconsistent with the CDC guidelines for treatment. Health care providers should be familiar with prevention, recognition, and treatment of malaria and are encouraged to consult appropriate sources for malaria prevention and treatment recommendations .P. falciparum, and one with P. ovale. The patient infected with P. ovale did not have severe malaria and died of complications related to other underlying conditions; this patient reportedly took chemoprophylaxis with unknown adherence. None of the other fatal cases took chemoprophylaxis for malaria prevention.Since 2000, the case-fatality rate from malaria has been <1.0%, with an average of 0.41%. In 2017, seven persons with malaria died, a case-fatality rate of 0.32%, which was equivalent to that in 2016 . In 2017, six of seven patients who died were infected with P. falciparum infections (70.5%) in 2017 is the highest recorded for 2012–2017, and since 2012 on average, 104.7 additional P. falciparum infections occurred each subsequent year. Because P. falciparum infections tend to have higher parasite densities than other species and have more recognizable features, they might be easier to diagnose than other species. Travel to the African region likely contributes to the large proportion of P. falciparum infections; the United Nations World Tourism Organization reported an overall increase in travel rates to sub-Saharan Africa, with 41.0 million international tourist arrivals reported for 2017, an increase from 38.9 million in 2016 (The proportion of undetermined species in 2017 is the lowest reported during 2012–2017 (10.5% in 2017). At the same time, the proportion of Although 99.7% of cases in the United States were classified as imported, in 2017, two cases of TTM occurred in the United States; in 2016, one TTM case occurred, after a 4-year period during which no cases of TTM were documented . In 2017, primaquine was the only antimalarial that was active against the dormant liver parasites to prevent relapses. During this time, the treatment recommendation was that all persons who receive a diagnosis of mosquito-acquired P. vivax or P. ovale and who are not G6PD deficient (confirmed by quantitative G6PD testing) should receive a 14-day course of primaquine to prevent relapses  and through routine malaria case surveillance.Primaquine use to prevent relapse from Treatment choices for pregnant women with uncomplicated malaria are limited to mefloquine or quinine plus clindamycin . Jurisdictions that implement malaria reporting via the NMI surveillance system will no longer be required to submit paper case report forms, which should improve the timeliness and accuracy of malaria surveillance in the United States. In addition, in 2019, CDC developed an electronic case report form for jurisdictions to use during the transition period to electronic reporting through NMI. State and local health departments are encouraged to report cases using the electronic NMSS case report form until malaria-specific data can be received electronically through NMI.The quality of malaria surveillance data can be limited if the data are incomplete or if definitions are incorrectly used. All sections of the malaria case report form should be completed because they provide information for examining malaria trends that are used to develop recommendations for malaria treatment and chemoprophylaxis. Local and state health departments, health care providers, and other health personnel should be vigilant in reporting complete information for malaria cases, especially for essential variables including species, residence, and country of acquisition. Incomplete reporting of antimalarial treatments and the infecting species could result in the patient being misclassified for receiving treatment according to CDC guidelines. CDC occasionally receives incomplete records for cases only reported electronically through NNDSS; these records contain basic demographic data but not the additional malaria case information from the NMSS case report form. CDC is collaborating with state and local health departments to update the NNDSS reporting platform through the NNDSS modernization initiative (NMI). Electronic submission of extended malaria data elements through NMI was initiated in early 2020; jurisdictions interested in electronic reporting for malaria can find information at the CDC NMI website  became available in the United States to prevent malaria, which has a weekly dosing schedule for adults who are not pregnant or G6PD deficient. Prevention recommendations tailored for each country are available online . CDC biannually publishes recommendations in Health Information for International Travel (commonly referred to as the Yellow Book), which is available and updated on the CDC Travelers’ Health website   .


Material and Methods. The study was a hospital-based cross-sectional study that took place from January to July 2020 where 203 children were involved. Blood samples were collected from the children and thick blood smears were prepared and examined microscopically for malaria parasites. Stool samples were also collected and examined through the Kato-Katz technique for the identification of helminth eggs. Demographic and socioeconomic data and information of participant's knowledge on the transmission of malaria and helminth infections were collected with the use of a well-structured questionnaire.  Malaria and helminth infections are major public health issues in sub-Saharan Africa including Cameroon. This study was aimed at determining the prevalence and risk factors associated with malaria and helminth coinfection among children in the Douala Gyneco-Obstetric and Pediatric Hospital (HGOPED) in Douala, southwestern Cameroon. P. falciparum infection was 28.8%, while the overall prevalence of helminth was 9.36%. The only species of helminth identified were Ascaris lumbricoides and Trichuris trichiura with a prevalence of 4.26% and 2.95%, respectively, and mixed infection of both A. lumbricoides and T. trichiura with a prevalence of 1.47%. Coinfection of malaria and helminth was observed with a prevalence of 6.90%. Associations of malaria-helminth coinfection with age groups, parent's educational level, type of latrine, and source of water factors were not statistically significant (p > 0.05), while the prevalence of the coinfection with respect to parent's occupation, presence of stagnant water around homes, washing of hands after using the toilet, and washing of fruits before eating was statistically significant (p < 0.05).  The overall prevalence of  The findings suggest that helminths and malaria infections tend to occur in children. Not washing hands after using the toilet, not washing fruits before eating, the presence of stagnant water around homes, and parents' occupation were found to be strongly associated with coinfection. Health education on the importance of better sewage disposal, draining of stagnant water around homes, and other sanitary practices is recommended. It is estimated that over a third of the world's population, mainly living in the tropics and subtropics, are infected by at least one intestinal helminth (worm) or a protozoan parasite species , 2 whichPlasmodium through the bite of an infected female Anopheles mosquito [Plasmodium protozoan parasites, Plasmodium falciparum is the most dangerous. Malaria is widespread in tropical and subtropical parts of America, Asia, and Africa. Each year, there are more than 250 million cases of malaria, killing between 1 and 3 billion people, the majority of whom are young children in sub-Saharan Africa [Malaria is a febrile illness caused by an infectious parasitic protozoan of the genus mosquito . Though Ascaris lumbricoides), whipworm (Trichuris trichiura), and hookworm . They are so-called soil-transmitted helminths because their infection on man is transmitted via contaminated soil by parasitic invasive eggs or larvae.In addition to malaria, other parasitic diseases are common among the world's poorest people. According to Hotez and David , there aPlasmodium falciparum being the most prevalent and virulent species of malaria parasite [A. lumbricoides, T. trichiura, A. duodenale, and Strongyloides stercoralis are the major helminth species [In Cameroon, both malaria and helminth infections coexist and are ranked among the major causes of parasitic mortality and morbidity with parasite –8. The p species –11. This species .This study aims to determine the prevalence and risk factors associated with malaria and helminth coinfection among children in the Douala Gyneco-Obstetric and Pediatric Hospital to contribute to the existing data on coinfection of malaria and helminth in Cameroon, making recommendations for further regional and nationwide control programs.The study was conducted in the Douala Gyneco-Obstetric and Pediatric Hospital (HGOPED). Douala, which is the largest city of Cameroon, is found in the littoral region of the country with around 2.5 million inhabitants. It is located at latitude 4°3'41.5296”N and longitude 9°47'9.8592”E within the Congo-Guinean phytogeographic zone near the Atlantic coast and lies about one meter above sea level.n = required sample size, Z = confidence interval at 95% , P = estimated prevalence, q (1−p) = expected nonprevalence, and d = margin of error at 5% (0.05) or maximum tolerable error.This study was a hospital-based cross-sectional study. The study population was made up of children (1 to 16 years old) of both sexes  present at the Douala Gyneco-Obstetric and Pediatric Hospital whose written and signed parental/guardian consent was obtained for participation in the study. The sample size was be determined using Lorenze's formula:The estimated prevalence of 22.1% (0.0221) was used:It is approximately 265 subjects.All children from 1 to 16 whose parents/guardians accepted to give his/her consent were included.Children whose parents/guardians refused to give his/her consent were immediately excluded.In order to collect primary data, all consented participants assisted by their parents/guardians were given a well-structured questionnaire designed to collect personal and sociodemographic information such as age and sex of the pupil, characteristics of their homes, and their knowledge on the transmission of malaria and soil-transmitted helminth infections.Well labelled sterile containers with individual identification number were distributed to all participants who were instructed on how to do a proper fresh fecal sample collection. The stool samples collected were taken to the laboratory and examined immediately.Parasitological examination of stool sample was done using the Kato-Katz technique . After sp < 0.05.Data collected and stored in a computer using Microsoft Excel 2013 was transferred to XLSTAT. Data obtained was analyzed using descriptive statistics where variables were summarized using frequencies and percentages. Chi square test was used to test for the association between malaria and helminth coinfection and its related risk factors and Pearson correlation was used to test the strength of the association between variables. The statistical significance threshold was set at A. lumbricoides infections, 6 (2.95%) had T. trichiura infection, and 3 (1.47%) had both A. lumbricoides and T. trichiura.p values and Pearson correlation values presented on p=0.001). It also reveals that washing fruits before eating and patients' behavior of “sometimes” washing their fruits before eating were significantly associated with malaria-helminth coinfection (p=0.001); equally the presence of stagnant water and unemptied bottles around patient were significantly associated with coinfection (p=0.001). Parents' economic status of having “no job” was strongly associated with coinfection (p=0.043).From the This study shows an overall malaria prevalence of 28.8% which is slightly similar to 33% observed by Laurantine et al.  in TombeThe overall prevalence of STH registered in this study was 8.87% which is lower compared to that observed in a similar study conducted by Zeukeng et al.  in the MThe overall prevalence of malaria-helminth coinfection obtained from this study was 6.8% which was similar to 7.1% prevalence obtained by Laurantine et al.  on a simThere was a higher prevalence (51.14%) of malaria-helminth coinfection in children less than 5 years of age than in other age groups. This differs from the report of Zeukeng et al.  in Mfou p=0.036), followed by no job and casual workers compared with no case of coinfection observed in children of civil servants. This may be explained by the fact that parents with no job, casual workers, and self-employed ones have low household income leading to poor feeding habits and consequently coinfection. This observation agrees with a previous study conducted by Lanne [Based on the parent's occupation, a high prevalence of coinfection of 8 (87.14) was recorded in children whose parents were self-employed (by Lanne  in Sierrp=0.001), and the presence of stagnant water pools around homes were strongly associated with malaria-helminth coinfection. This agrees with the previous studies conducted by Nkuo-Akenji et al. [Anopheles mosquitos, hence making coinfection inevitable.It was also observed that poor sanitary practices such as not washing hands after using the toilet, not washing fruits before eating (i et al.  in the Si et al.  in CongoThe study reveals that there is coinfection of malaria and helminth among children in the Douala Gyneco-Obstetric and Pediatric Hospital. Poor hygiene practices such as not or “sometimes” washing hands after using the toilet, not washing fruits before eating, poverty resulting from parents having no job, and the presence of stagnant water pools around homes are significantly associated with malaria-helminth coinfection among children in the Douala Gyneco-Obstetric and Pediatric Hospital.