[Epidemiological study on the influence of pig-derived Ascaris to the transmission of human ascariasis].

OBJECTIVE

An experimental epidemiological study was designed to investigate possible relations of pig-derived Ascaris to the transmission of human ascariasis which might be caused by cross-infection between the pig and humans.

METHODS

In Xinjian County, Jiangxi province, two adjacent villages, Laozhi and Panzhi, with similar baseline of ascariasis in pig and human populations were selected as the study sites with a one-year longitudinal epidemiological follow-up study. People in the two villages received mass chemotherapy. Pigs received mass chemotherapy only in Panzhi village and was twice repeated with two months interval, while pigs in Laozhi village were not treated at all. In the following year after treatment on humans, ascariasis among villagers was studied cross-sectionally five times with Kato-katz technique.

RESULTS

No significant difference of the re-infection patterns of human ascariasis was found between the two villages in terms of prevalence and intensity during the following year in all the five surveys (chi(2) < 0.658, F < 1.658 and P > 0.1).

CONCLUSION

The results suggested that pig-derived Ascaris were mainly transmitted among pigs but had no important role on the transmission of human ascariasis. The results were in good accordance with the findings through a recent molecular genetic research on the local human-and pig-derived Ascaris worms. Possible confounding factors were discussed.