Helminth Zoonoses

Volume 43 of the series Current Topics in Veterinary Medicine and Animal Science pp 106-118

Zoonotic Trematodiasis in South-East and Far-East Asian Countries

  • V. Kumar

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Zoonotic trematodiasis constitute a public health problem of considerable magnitude in many countries of South-east and Far-east Asia. These infections are caused by the digenetic trematodes of various genera and have a high rate of prevalence in the countries of their endemicity.

The trematode infections of the SE and FE Asian countries which are zoonoses and which involve the extra-intestinal organs of the mammalian host cause well known diseases as these affect the vital organs and cause spectacular pathology. The diseases like Clonorchiasis, opisthorchiasis, paragonimiasis and schistosomiasis affecting the biliary system, lungs and hepato-intestinal tissues of the host need special mention. Clonorchiasis, opisthorchiasis and paragonimiasis are sea-food borne infections acquired through the ingestion of infected fishes, crabs and cray-fishes. Certain food habits of the ethnic communities have important bearing on their transmission dynamics. Schistosomiasis is water-borne and exposure of the paddy field farmers, bathing and doing laundry in waters contaminated with schistosome cercariae constitute major means of human infection.

The trematodes inhabiting the intestinal tract may also arouse varying grades of pathological effects. Gastrodiscoides hominis, Fasciolopsis buski and Artyfechinostomum malayanum are found in the intestine of humans and in all these three instances the local pigs of SE and FE Asia serve as the reservoir host. Close association of the farming communities with their local pigs assists their dissemination through the molluscan vector. Dogs and cats serve as hosts of certain zoonotic trematode infections like Heterophyes heterophyes, Metagonimus yokogawai, Haplorchis spp. etc. These intestinal trematode parasites are transmitted through ingestion of infected fishes. Echinostoma ilocanum, E.lindoense and E.hortense are other trematodes found in the intestine of humans.

Since the advent of praziquantel, the chemotherapy of many of the aforementioned infections may have been resolved to a great extent though other integrated control measures are indispensable in achieving a substancial reduction in their incidence.