RESUMO
Background: Fish-borne trematode infection is a parasitic zoonosis with a great variety of clinical manifestations. According to current information, the metacercaria of heterophyid trematode can be found in freshwater fish, especially the cyprinoid group. Objective: To investigate the prevalence of Heterophyidae metacercariae in freshwater fish. Material and methods: A parasitological investigation was done using 129 fish from 17 species: Labiobarbus siamensis, Puntioplites proctozysron Barbodes gonionotus, Barbodes altus, Henicorhynchus siamensis, Hampala macrolepidota, Mystacoleucus marginatus, Notopterus notopterus, Pristolepis fasciatus, Anabas testudineus, Puntius brevis, Poropuntius deauratus, Cyclocheilichthys armatus, Osteochilus hasselti, Labiobarbus spilopleura, Lobocheilus davisi and Rasboratornieri. The fish were caught during the rainy season (June-September 2007) in the Chiang Mai water reservoirs (Mae Ngad and Mae Kuang) and the Chiang Rai water reservoirs (Nong Luang and Mae Tak). Results: The prevalence of heterophyid metacercariae infection at Mae Ngad, Mae Kuang, Nong Luang and Mae tak were 37.83%, 51.35%, 12.00% and 63.33%, respectively. Conclusions: There is a high prevalence of Haplorchis metacercarial infection in cyprinoid fish. The highest intensity of heterophyid metacercariae infection in Barbodes gonionotus was in Mae Kuang at 104.
RESUMO
A parasitological investigation on trematode metacercariae was made on 62 freshwater fishes of 13 species in northern Thailand; Cyclocheilichthys apogon, Puntioplites proctozysron, Labiobarbus siamensis, Barbodes gonionotus, Barbodes altus, Henicorhynchus siamensis, Osteochilus hasselti, Notopterus notopterus, Mystacoleucus marginatus, Anabas testudineus, Systomus orphoides, Morulius chrysophykadian, and Hampala macrolepidota. The fish were caught over the summer period (February-May 2007) from 2 Chiang Mai water reservoirs, i.e., the Mae Ngad (UTM 47Q E 503200, 47Q N 2119300) and the Mae Kuang Udomtara (UTM 47Q E 513000, 47Q N 2092600) Reservoirs in Chiang Mai province, Thailand. The prevalence of heterophyid (Haplorchis taichui and Haplorchoides sp.) metacercariae in these fish was 83.9% and 74.2% in the Mae Ngad and Mae Kuang Udomtara Reservoirs, respectively. The highest intensity of heterophyid metacercariae in H. siamensis in the Mae Ngad was 120.4 and that in P. proctozysron in the Mae Kuang Udomtara was 180.0. The fish, A. testudineus, C. apogon, and M. chrysophykadian, were not found to be infected with H. taichui metacercariae. The results show that the freshwater fish in Chiang Mai water reservoirs are heavily infected with H. taichui and Haplorchoides sp. metacercariae.