Seven outbreaks of trichinosis in China (1992-1996).

Seven outbreaks of trichinosis occurred in Zhengzhou (central China) from 1992 to 1996, 250 patients were diagnosed. Trichinella larvae were found in 3 of 4 portions of the pork examined and in 5 of 7 cases by muscle biopsy. There was a higher occurrence of outbreaks in winter. Young and middle-aged workers, cadres and merchants were the majority of patients, (higher in males than in females). The most important clinical manifestations were fever, eyelid edema, tiredness and eosinophilia without any gastrointestinal symptoms, rash and with less myalgia. Anti-Trichinella antibodies were detected by IF in 62.6% individuals with the history of infection. The specific antibodies were only observed in 78% patients one week after onset of disease, while the antibody positive rate was increased to 92.5%, 97.6% and 100% two, three, four and five weeks after the onset and evidently increased from 89.6% before therapy to 100% one week after therapy, and decreased to 74.6% and 23.7% one and four months after therapy respectively, which suggested that IF was a useful tool for immunodiagnosis and checking up therapeutic effect of trichinosis.