A survey of epidemiology of Gnathostoma hispidum and experimental studies of its larvae in animals.

The present study is concerned with a survey of the epidemiology and infectivity of Gnathostoma hispidum larvae in animals. A total or 3,478 pigs were examined in Hongze-Lake, Jiangsu; Po-Lake, Anhui; and Jiujiang, in Jiangxi Province. The infection rate of G. hispidum in pigs was 14.9%. The prevalence in pigs in the lake districts (26.4%) was considerably higher than in the mountainous districts (5.1%). The results of field surveys and experimental studies revealed that in China, 38 animal species served as the first and the second intermediate hosts and paratenic hosts of G. hispidum. Among them, 23 species (6 cyclops, 13 fish, 2 frogs and one each of snake and bird) were similar to the hosts of G. spinigerum. Carnivorous fish, frogs and rodents are an important infection source for gnathostomiasis. Experiments demonstrated that Macaca mulatta was successfully infected with the early 3rd-stage larvae from cyclops or the advanced 3rd-stage larvae from fish. The domestic cat and white rat were experimentally infected by skin penetration by advanced 3rd-stage larvae of G. hispidum obtained from fish; the results of the test were all positive. The survey of epidemiology and biology of G. hispidum and G. spinigerum were quite similar, so the authors consider that humans may be infected by G. hispidum.