Typhoid Fever
Typhoid fever is caused by the gram positive bacillus Salmonella typhi. Paratyphoid fevers, which are usually milder but may be clinically indistinguishable, are caused by Salmonella paratyphi A, Salmonella schotiilleri, or Salmonella hirschfeldii (formerly Salmonella paratyphi A, B, C). Children usually have a shorter incubation period than do adults (usually 5 – 8 days instead of 8 – 14 days).
The organisms enter the body through the walls of the intestinal tract and, following a transient bacteremia, multiple in the reticuloendothelial cells of the liver and spleen. Persistent bacteremia and symptoms then follow. Reinfection of the intestine occurs as organisms are excreted in the bile, bacterial emboli produce the characteristic skin lesions. Symptoms in children may be mild or severe, but children under age 5 years really have severe typhoid fever.
Typhoid fever is transmitted by the fecal oral route and by contamination of food or water. Unlike Salmonella species, there are no animal reservoirs of S typhi; each case is the result of direct or indirect contact with the organism or with an individual who is actively infected or a chronic carrier.
About 500 cases per year are reported in the United States, 60% of which are required during foreign travel.
Typhoid Fever
