Paratyphoid fever is caused by any of three serovars of
Salmonella enterica subsp. enterica:
S. Paratyphi A,
S. Paratyphi B (invalid alias
S. schottmuelleri),
S. Paratyphi C (invalid alias
S. hirschfeldii).
Transmission They are usually spread by eating or drinking food or water contaminated with the
feces of an infected person. Diagnosis is with isolation of the agent in blood or stool and demonstration of antibodies antiBH in the
Widal test. The disease responds well to
chloramphenicol or
co-trimoxazole.
Salmonella Paratyphi B strains causing paratyphoid fever do not ferment
dextrorotatory tartrate.
Paratyphoid C Paratyphoid C is a rare infection, generally seen in the Far East. It presents as a
septicaemia with
metastatic abscesses.
Cholecystitis is possible in the course of the disease.
Antibodies to paratyphoid C are not usually tested and the diagnosis is made with blood cultures. Chloramphenicol therapy is generally effective.
Carriers Humans and, occasionally, domestic animals are the carriers of paratyphoid fever. Members of the same family can be transient or permanent carriers. In most parts of the world, short-term fecal carriers are more common than urinary carriers. The chronic urinary carrier state occurs in those who have schistosomiasis (parasitic blood fluke). Continuing to shed
Salmonella Paratyphi is possible for up to one year, and during this phase, a person is considered to be a carrier. The chronic carrier state may follow acute illness, or mild or even subclinical infections. Chronic carriers are most often women who were infected in their middle age. ==Pathophysiology==