cryptosporidium , a spore - forming protozoon , has been recognized as a human pathogen since 1976 . the species most frequently involved in human infections are cryptosporidium hominis , which primarily infects humans , and cryptosporidium parvum , which infects humans and animals such as cattle , although infection with unusual species and genotypes occurs in both immunocompetent and immunocompromised populations . in immunocompetent individuals , infection causes self - limited watery diarrhea . while , in patients with immune deficiencies , cryptosporidiosis may present as chronic or severe life - threatening diarrhea . in children , mainly those living in developing countries are known to cause traveler 's diarrhea   and they are also responsible for outbreaks of diarrhea , including a memorable outbreak in milwaukee , wisconsin , in 1993 during which nearly 403,000 people developed cryptosporidiosis due to contamination of drinking water . antimotility drugs play a key role in the treatment of cryptosporidiosis in both immunocompetent and immunocompromised individuals , while the efficacy of antiparasitic drugs in cryptosporidiosis remains controversial , particularly in immunocompromised individuals . a recent meta - analysis of trials of antiparasitic drugs in cryptosporidiosis revealed significant improvement of non - aids patients with nitazoxanide , but no clear evidence of efficacy for other antiparasitic drugs in cryptosporidiosis or for nitazoxanide in aids patients . we describe the clinical and parasitological course of a child with cryptosporidiosis , who was treated successfully with nitazoxanide ( alinia , romark laboratories ) . a 16-month - old child was admitted to the pediatrics department of amiens university hospital ( france ) for diarrheal syndrome associated with rhinitis . he was born in france to french parents living in a rural area who had never been outside of france . the child 's father was a dairy farmer and his mother did not work on the farm . the child did not have any particular family history , but had a personal history of acute otitis media and rhinopharyngitis . his immune status was not investigated , but on the basis of this history of frequent rhinitis , a respiratory allergy was suspected and treated with antihistamine . the child presented to our institution with a six - day history of fever , rhinitis , vomiting , and profuse diarrhea . he was moderately dehydrated with very minor signs of dehydration such as weight loss , deep - set eyes , but no disorders of consciousness . on initial physical examination , the young patient was afebrile but presented tachycardia of 124  bpm , a respiratory rate of 18/min , and blood pressure of 82/52  mmhg . chest , cardiac , and abdominal examinations were normal . on ear - nose - throat examination , the tympana could not be seen due to earwax and the throat was erythematous . one day after admission , after removal of earwax , ear examination revealed bilateral acute otitis media . the patient was placed on intravenous fluids and oral cefpodoxime was started while waiting for laboratory results . the laboratory work - up revealed white blood cell count : 10,200  cells / mm with 46% neutrophils , 41% lymphocytes , 10% monocytes , 3% eosinophils ; hemoglobin : 13.3  g / dl ; platelets : 477,000/mm . blood biochemistry showed hyponatremia ( 130  mmol / l ) and decreased alkaline reserve ( 19  mmol / l ) . stool specimens were also sent for routine bacterial culture , rotavirus / adenovirus antigen , giardia antigen , clostridium difficile antigen , and all were negative . routine stool examination for enteric parasites including direct saline wet mount examination and two concentration techniques : bailenger 's method and mif ( merthiolate iodine formaldehyde ) with both a fixative and a stain was negative . cryptosporidium antigen was detected in stool by the immunochromatographic method ( rida quick cryptosporidium , r - biopharm diagnostic ) . modified ziehl - nielsen staining of a stool smear showed several cryptosporidium oocysts , up to 2,400 per gram of stool . polymerase chain reaction - restriction fragment length polymorphism ( pcr / rflp )   identified the species as cryptosporidium parvum . three - day treatment ( 100  mg twice daily ) with nitazoxanide suspension ( alinia , romark laboratories , fl , usa ) was then initiated . oocysts were no longer detected in stool using the modified ziehl - nielsen stain and immunochromatographic methods , while pcr detection was still weakly positive . eradication of oocyst excretion was observed on the day-7 stool sample and pcr detection was also negative ( figure 1 ) . cryptosporidium infections obviously do not represent a major public health threat in developed countries , although recurrence of gastrointestinal symptoms due to cryptosporidium is frequently reported , for example , in the milwaukee outbreak in 1993 and in sporadic cases in europe . in most sporadic cases , the source of infection is difficult to ascertain as many risk factors are commonly encountered in everyday life . several factors facilitate transmission of cryptosporidium and account for the propensity to cause large - scale outbreaks of diarrhea . it is frequently identified in farm animals , particularly calves , and in domestic animals ; ( ii ) the oocyst is very resistant and can conserve its infectivity in moist environments for a long time ; ( iii ) cryptosporidium genus is composed of a large number of species , several of which can infect humans ; ( iv ) the infectious dose is very low , and infected individuals excrete large numbers of oocysts , up to 10 in a single day . public health surveys of cases must investigate all forms of exposure during the two weeks prior to onset of the illness in order to identify the source of contamination . in the present case , the child 's father was a dairy farmer and the family lived 3  km from the farm . two years prior to onset of the child 's illness , the father reported cryptosporidium - related loss of calves in his livestock . the child had never been on the farm , and therefore had never had any contact with the animals . parasitological stool examinations including specific methods for cryptosporidium oocyst detection of other family members were negative , although the father reported occasional gastrointestinal disorders . cryptosporidium parvum identified in the child and the documented presence of cryptosporidium in the father 's livestock are both in favour of these animals as the source of contamination , with transmission via the father . [ 11 , 12 ] , this case report confirms the efficacy of nitazoxanide for the treatment of cryptosporidiosis in immunocompetent children . however , the role of the child 's immune system in this rapid clearance of the parasite remains unknown . the negative result of cryptosporidium antigen detection in stool observed immediately after the 3-day course of nitazoxanide is an interesting finding , suggesting that the rapid immunochromatographic method could be used for posttreatment stool tests instead of more time - consuming staining or pcr methods . this case highlights the need to consider spore - forming protozoa as potential causes of diarrhea in children . parasite - related diarrhea in both immunocompetent adults and children is probably underestimated due to underdiagnosis . in contrast with bacterial and viral agents , parasites are less frequently considered by physicians as a potential cause of diarrhea . clinical pathologists should therefore systematically perform screening for spore - forming protozoa in all patients with persistent or acute watery stools .