Schistosoma incognitum and its zoonotic potential role in Phitsanulok and Phichit provinces, northern Thailand.

A study on Schistosoma incognitum, a blood fluke of a variety of mammals, was conducted in different ecological conditions in Phitsanulok and Phichit, northern Thailand. The intermediate host of S. incognitum in permanent water habitats studied, i.e; swamps and ditches is Radix (Lymnaea) auricularia rubiginosa. Of 44,412 mollusks representing 13 different species collected from 24 water habitats studied, 7,186 were R. a. rubiginosa. S. incognitum infection rate in the snails was 2.1%. 483 Rattus rattus, 8 R. argentiventer, 280 Bandicota indica and 65 B. savilei were found infected with S. incognitum with an overall infection rate of 41.7%. R. argentiventer and B. savilei are reported as new mammalian hosts of the parasite. Also, 3.9% of dogs in the study area were found excreting S. incognitum eggs in their stools for the first time. The possibility of S. incognitum as a zoonotic potentiality to humans is discussed and is still an equivocal issue deserving further study.