PRESENCE OF METACERCARIAE OF Opisthorchis sp. BLANCHARD, 1895 (TREMATODA: OPISTHORCHIIDAE) IN NEW HOST Macrobrachium amazonicum (HELLER, 1862), FROM THE NORTHERN BRAZIL: AN EMERGING RISK TO HUMANS BY THE SHRIMP CONSUMPTION

Herein, we report the first observation of the metacercaria Opisthorchis sp. Blanchard, 1895 recovered from a new intermediate host Macrobrachium amazonicum (Heller, 1862), an important food resource from northern Brazil, emphasising the risk of contamination from inappropriate human consumption. The shrimp specimens of M. amazonicum were collected during June 2023, using a local trap called matapi in the Guamá River (01°27’54.2”S; 048°26’02.6”W), which supplies the city of Belém, showing a characteristic of an eutrophicated river. The collected specimens were sexed, measured, weighted and dissected in the carapace region, to observe the presence of parasites in gills, hepatopancreas and gonads. We observed 56 specimens of M. amazonicum (20 males, 32 females and 4 ovigerous females), of which thirteen individuals (23.21% of total sampled) showed encysted metacercariae of Opisthorchis sp. only in gonadal tissues, with high preference in females (66.6%), when compared with males (33.4%). The observation of metacercaria in Amazon river prawn is a risk to human health, due to the parasite's life cycle being completed in humans, leading to several health problems such as hepatic and biliary degradation, diarrhoea, vomiting and respiratory problems. Additionally, the eutrophication process observed in the Guamá River may favour parasite proliferation, and dissemination to other hosts and regions, possibly increasing the cases of people infected with parasites in Belém metropolitan area. Based on that, this work is an alert to the authorities for the risk of contamination of the population due to inadequate consumption of (molluscs, crustaceans and fishes) from the eutrophic waters of the Guamá River and adjacent waters.