( CNN ) -- Texas health officials are recommending that state residents make sure they 're vaccinated against pertussis , a sometimes fatal disease that is on track to sicken more Texans this year than at any time in decades . `` If we continue to have cases in Texas at the rate we 've had them so far this year , we 'll have more cases than has been reported for the last 50 years , '' said Dr. Carol J. Baker , professor of pediatrics at Baylor College of Medicine and executive director of the Center for Vaccine Awareness in Research at Texas Children 's Hospital in Houston . The threat grows when one considers that scientists estimate 10 cases of pertussis , popularly known as whooping cough , occur for every one reported , she said in a telephone interview , adding , `` We 're clearly having an epidemic . '' So far this year , Texas has tallied nearly 2,000 cases , two of them fatal , and the total is expected to exceed the 3,358 recorded in 2009 , when the last such outbreak occurred , the Department of State Health Services said . There does not appear to be any single explanation for the spike , said Chris Van Deusen , a spokesman for the department . `` It really looks like several things working together , '' he said in a telephone interview , noting that outbreaks tend to occur in cycles . `` We see a peak and a lot of people will be exposed and develop natural immunity , '' leading to fewer cases . `` Then it wears off and it ( the number of cases ) will go up again . '' It is not clear how much bigger this outbreak is when compared with previous ones . That 's because increased public awareness and improved diagnostic tests appear to have led to more cases being identified , he said . But there is no debate about the seriousness of the disease . As many as two in 100 adolescents and five in 100 adults with pertussis are hospitalized or have complications , including pneumonia and death , according to the Centers for Disease Control and Prevention . The federal health agency recommends that women get the vaccine during each pregnancy , ideally between the 27th and 36th week -- since an estimated 30 % to 40 % of babies who contract whooping cough get it from their mothers -- and that their children undergo a series of five pertussis vaccinations beginning at 2 months of age . That first shot is to be followed by injections at 4 months and 6 months , and boosters at 15 to 18 months and again at 4 to 6 years of age so that children 's immunity will be robust during the first months of life when they are most vulnerable . Both of the Texas fatalities were in children younger than 2 months . `` We want to make sure that they are getting the immunizations on that schedule so that the waning immunity wo n't be as much of an issue , '' Van Deusen said . A separate vaccine is recommended for children ages 11 to 13 and for adults . It is considered especially important for people who are around newborns since the bacteria that cause the disease spread easily . Antibiotics are used to treat the disease . Texas ' peak is not being replicated nationwide , according to the CDC . The numbers are declining this year , with 14,270 cases reported through August , compared with 32,680 cases through August 2012 . A CDC spokesman said he was aware of no major outbreaks this year . `` We do not keep a comprehensive list of pertussis outbreaks since states only alert CDC to those if they need assistance , '' said Jason McDonald in an e-mail . But Washington state declared an epidemic last year , and California did so in 2010 . `` It 's our turn , '' Baker said of Texas . Since January , her hospital in Houston has seen 63 pertussis patients younger than 7 months of age , 62 % of whom were hospitalized , she said . Of those , 41 % were treated in the intensive care unit , three of them for more than a month . `` It 's a very severe disease , '' she said . The younger the patients , the greater the risk to their lungs . `` All those airways are small , '' she said . `` When they 're all blocked up , it 's a huge problem , and they have to go on breathing machines and sometimes cardiac bypass just to get oxygen into the brain . '' The disease can cause coughing so violent that patients ' ribs fracture and they pass out . Pertussis got the name whooping cough because of the characteristic sound some stricken patients make . `` Children have a whoop after the cough because they 're out of breath , so they go 'whoop , whoop , ' `` Baker said . Increasing vaccination rates are a problem , particularly because the series required to confer protection is so complex . Though more than 90 % of children nationwide get the first three doses , the number who get boosters is far lower , said Baker , who served from 2008 to 2010 as chair of the CDC 's Advisory Committee on Immunization Practices , which sets U.S. policy on vaccines . In all , 45 % of pregnant women at Texas Children 's Hospital Pavilion for Women get inoculated during pregnancy , far outstripping the state average of less than 10 % , but that 's not good enough , she said . `` We need to do better . '' During the 1930s and 1940s , before widespread vaccination against pertussis , its annual toll comprised nearly 300,000 cases and more than 4,000 deaths , she said . In 2006 , there were 15,600 cases and 27 deaths . Still , pertussis is the most prevalent disease among the pantheon of illnesses against which Americans get vaccinated , and there is no indication that it will go away soon , said Baker , who cited as obstacles to progress those parents who refuse the vaccine for their children and those adults who do n't know they need it . Though reporters may be writing about Texas this year , they could easily be writing about New York or Georgia next , she said . `` Pertussis is going to be , in my prediction , an ongoing problem . ''
Ten pertussis cases have been reported in California . `` We 're clearly having an epidemic , '' a pediatrics professor says . Nearly 2,000 cases are estimated to occur for every one that 's reported . Nationwide , the number of cases is down 2 months of age , the the Center for Vaccine Awareness in Research says .