An outbreak of paratyphoid A in Singapore: clinical and epidemiological studies.

The epidemiological and clinical findings of 61 cases of laboratory-confirmed paratyphoid A reported in an outbreak in 1979 were described. Epidemiological investigations of 42 indigenous cases implicated imported fresh oysters as the vehicles of transmission (p less than 0.01). Although S. paratyphi A could not isolated from the implicated oysters, several observations presented tend to support the association between oyster consumption and illness. The clinical features were similar to typhoid, 82.8% of the organisms were isolated from blood cultures. The relapse rate was 8.6%. There were three stool and one urinary convalescent carriers. Two of the stool carriers were treated with cholecystectomy.