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The effectiveness of different intervention strategies for the prevention of zoonotic metacercariae infection in cultured fish

Author:
Clausen, Jesper H., Madsen, Henry, Murrell, K.D., Bui, Thanh N., Nguyen, Nguyen T., Do, Dung T., Thi, Lan Anh N., Manh, Hung N., Dalsgaard, Anders
Source:
Aquaculture 2013 v.416-417 pp. 135-140
ISSN:
0044-8486
Subject:
Labeo rohita, Trematoda, aquaculture, birds, carp, cats, cercariae, disability-adjusted life year, dogs, drug therapy, experimental design, farm management, farmed fish, farmers, farms, fingerlings, hosts, humans, juveniles, metacercariae, pollution, ponds, product quality, public health, risk, runoff, snails, urban areas, Vietnam
Abstract:
Fish-borne zoonotic trematodes (FZT) are a major public health problem. It is estimated that in Vietnam 26,366 “disability-adjusted life years” (DALYs) are lost due to FZT. Fish from aquaculture are a main source of protein and of great economic importance in both rural and urban areas. The objective of this study was to compare the impact on transmission of FZT to juvenile fish of drug treatment intervention of final hosts, and pond management interventions on fingerlings produced in nurseries producing Rohu carp in Northern Vietnam. The study design was a parallel group design of nurseries with two intervention groups; a drug treatment of human and animal groups and a farm management group (control of snail vectors and fecal pollution of pond). A third group (non-intervention) served as control. Fish were examined for FZT metacercariae prevalence and intensity before and after interventions, along with density of potential host pond snails. Fecal exams for FZT infections in farm household humans, dogs and cats were also performed. The results showed that although FZT prevalence in fish was not significantly reduced, the intensity of metacercariae in fish from ponds receiving management interventions was reduced 91.7% compared to before interventions. The intensity of FZT was also significantly lower in the pond management group, compared to the drug treatment group and the control group after interventions. The results demonstrate that improving farm and pond management practices can be effective in reducing FZT infections without using drug treatment. This study also highlighted certain obstacles to attaining higher levels of protection for which more research is needed. A major challenge is the ability to completely isolate (or bio-secure) the pond from its surrounding environment, especially surrounding water sources which may harbor snails and cercariae that can contaminate the pond through water resupply or runoff. Another is the unknown risk from piscivorous birds, host for intestinal FZT. The strategies employed in this study now need long-term evaluation on a regional basis, the outcome of which could be the development of good management practices crucial to ensuring a good quality product that benefits farmers and the consumers.
Agid:
374281