[Parasitic zoonoses in Japan, with special reference to the current topics]

The present situation of parasitic zoonoses in Japan is reviewed. A total of 51 species, i.e., 6 species of protozoan parasites, 14 species of trematode parasites, 11 species of cestode parasites, 18 species of nematode parasites and 2 species of acanthocephalan parasites are potential zoonotic parasites. Most (11 species) of the zoonotic nematodes provoke larva migrans. Habitats of zoonotic parasites vary greatly depending upon individual species. Some parasites cause heterotopic parasitism (e.g., Paragonimus westermani) and metastasis (Entamoeba histolytica). In larva migrans, parasites migrate through various parts of body tissues, affecting multiple organs (gnathostomiasis and sparganosis mansoni). The majority of parasitic zoonoses are food-borne infections. Some of them are an arthropod-borne (or -mediated) infection (dirofilariasis, thelaziasis and moniliformiasis), or acquired by percutaneous infection with cercariae (schistosome cercarial dermatitis) or 3rd-stage infective larvae (hookworm diseases). The diagnosis of parasitic zoonoses, especially larva migrans, is difficult; although some unique clinical symptoms and the presence of eosinophilia and/or increased level of serum IgE antibody are frequently seen in larva migrans, the application of various immunodiagnostic methods is usually required. For the prevention and control of parasitic zoonoses, the ingestion of not only strange food (e.g., snakes, frogs, slugs, etc.) but also raw fish and cuttlefish (sashimi) must be prohibited. Fishes and the meat of wild animals (e.g., bear and wild boar) should be frozen or thoroughly cooked before eating. Pets and domestic animals play an important role as a direct or indirect source of infection with various parasitic zoonoses. The treatment of those animals and/or the eradication of intermediate hosts (or vectors) of the parasites are thus required.