Despite the availability of typhoid fever vaccines since late 1980s, the public health program use of typhoid fever vaccines has been limited. As part of the disease of most impoverished program (DOMI) a cluster randomized trial was conducted in three urban squatter settlements of Karachi, Pakistan. The population of the study setting was enumerated by a household census followed by enhanced passive disese surveillance to enroll children with the history of fever for three or more days. A 5–10ml volume of venous blood was collected for microbiologic confirmation of enteric fever.
Results. Following a fixed cohort approach the annual incidence of culture proven S. typhi and S. paratyphi A in the study setting was estimated to be 451 (95% C.I: 446–457) and 76 (95% C.I: 74–78) per one hundred thousand (2–16 years) population respectively. 27,231 children between the ages of 2 and 16 years were vaccinated with Vi capsular polysaccharide vaccine (13,228) and Hepatitis A control vaccine (13,993). Typhoid fever was diagnosed in 30 Vi vaccine recipients and 49 Hepatitis A vaccine recipients with an adjusted total protective efficacy of 31% (−28%–63%) after two years. The adjusted total vaccine protective efficacy for children age 2 to 5 years was −38% (−192 %–35%) and for children 5 years and older was 57% (6 %–81%).
Conclusion. Vi vaccination of the school age children in general and all ages in high population density areas will have significant impact on reduction of typhoid fever burden in urban Pakistan. However; a combination of environmental and biological interventions similar to industrialized countries is required to prevent the continued epidemiological and economical devastation by typhoid fever in the vulnerable population of Pakistan.
|School:||The Johns Hopkins University|
|School Location:||United States -- Maryland|
|Source:||DAI-B 71/11, Dissertation Abstracts International|
|Subjects:||Public health, Epidemiology, Immunology|
|Keywords:||Infectious diseases, Pakistan, Typhoid fever, Vi capsular polysaccharide|
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