Prevention of Typhoid Fever

Typhoid fever, the generalized infection of the reticuloendothelial system (spleen, liver, and bone marrow), gut-associated lymphoid tissue, and gall bladder caused by the highly human host restricted pathogen Salmonella enterica serovar Typhi (S. Typhi), is the quintessential infectious disease associated with inadequate sanitation and lack of protected drinking water. The pediatric (school-age) and young adult populations in endemic areas bear the brunt of the clinical disease burden worldwide. Typhoid fever also represents a risk for pediatric and adult travelers from industrialized countries who visit the developing countries (Steinberg et al., 2004). In endemic areas, chronic gall bladder carriers (usually adult females who excrete large numbers of typhoid bacilli) constitute an important reservoir of infection (Levine et al., 1982). Where sanitation is deficient, fecal contamination from inapparent carriers (chronic or temporary) and clinically ill patients can contaminate water supplies. If treatment of water sources is inadequate or unavailable, water can serve as an important vehicle of transmission (Mermin et al., 1999). Consumption of contaminated water and food vehicles by susceptible subjects leads to clinical or sub-clinical infection, depending on the dose ingested, the precise vehicle conveying the typhoid bacilli, and the host susceptibility factors (Hornick et al., 1970). Depending on the age of the infected patient, the presence of pre-existent gall bladder pathology, and the specific antibiotic treatment administered, up to a few percent of infected persons can become chronic gall bladder carriers, thereby maintaining the reservoir of infection. A fairly long incubation period (8–14 days) follows the ingestion of typhoid bacilli before the onset of clinical disease. The typical general features of typhoid fever include fever (that increases in step-wise fashion and persists for weeks if improperly treated), headache, and abdominal discomfort.