| Popis: |
An epidemiological study of fishborne zoonotic trematodes (FZT) infecting three major catfish species, hybrid catfish (Clarias sp.), river catfish (Pangasianodon hypopththalmus) and black-spotted catfish (Pangasius larnaudii), produced locally in Ho Chi Minh City, Vietnam, was conducted during 2017-2018. The impact of seasonal changes associated with the wet and dry seasons was assessed. The only species of FZT found was Haplorchis pumilio, a new host record for black-spotted catfish. Farm prevalence of H. pumilio was highest for black-spotted catfish (20.0 %) and hybrid catfish (16.7 %), and lowest for farms producing river catfish (5.0 %). The FZT prevalence in hybrid catfish (N = 300 per season) was higher in the wet season (2.0 %) than in the dry season (0.3 %); however, it was not significantly different (P > 0.05). For all three catfish species (N = 550 per season), seasonal prevalence was significantly higher (P < 0.05) in the wet season than in the dry season (1.5 % versus 0.2 %). These results demonstrate that, overall, most aquaculture farmers in this area employed management practices that were effective in lowering the risk of parasite infection in grow-out catfish compared with prevalence data for catfish reported from the Mekong Delta. However, the basis for the seasonal effect is not clear. The increase in snail intermediate host populations and pond contamination with parasites eggs from surface run-off are risk factors, generally, but the significantly higher impact on hybrid catfish production requires further investigation. |
