Farm-level risk factors for fish-borne zoonotic trematode infection in integrated small-scale fish farms in northern Vietnam - PubMed (original) (raw)
Farm-level risk factors for fish-borne zoonotic trematode infection in integrated small-scale fish farms in northern Vietnam
Van Thi Phan et al. PLoS Negl Trop Dis. 2010.
Abstract
Background: Northern Vietnam is an endemic region for fish-borne zoonotic trematodes (FZT), including liver and intestinal flukes. Humans acquire the FZT infection by eating raw or inadequately cooked fish. The production of FZT-free fish in aquaculture is a key component in establishing a sustainable program to prevent and control the FZT transmission to humans. Interventions in aquaculture should be based on knowledge of the main risk factors associated with FZT transmission.
Methodology/principal findings: A longitudinal study was carried out from June 2006 to May 2007 in Nam Dinh province, Red River Delta to investigate the development and risk factors of FZT infections in freshwater cultured fish. A total of 3820 fish were sampled six times at two-month intervals from 96 fish farms. Logistic analysis with repeated measurements was used to evaluate potential risk factors based on information collected through questionnaire interviews with 61 fish farm owners. The results showed that the FZT infections significantly increased from first sampling in June to July 2006 (65%) to sixth sampling in April to May, 2007 (76%). The liver fluke, Clonorchis sinensis and different zoonotic intestinal flukes including Haplochis pumilio, H. taichui, H. yokogawai, Centrocestus formosanus and Procerovum varium were found in sampled fish. Duration of fish cultured (sampling times), mebendazole drug self-medication of household members, presence of snails in the pond, and feeding fish with green vegetation collected outside fish farms all had a significant effect on the development of FZT prevalence in the fish.
Conclusions/significance: The FZT prevalence in fish increased by 11 percentage points during a one-year culture period and the risk factors for the development of infection were identified. Results also highlight that the young fish are already highly infected when stocked into the grow-out systems. This knowledge should be incorporated into control programs of FZT transmission in integrated small-scale aquaculture nursery and grow-out systems in Vietnam.
Conflict of interest statement
The authors have declared that no competing interests exist.
Figures
Figure 1. A grow-out pond in Nam Dinh province.
Shown a typical grow-out pond in Nam Dinh province. The pond is earthen pond and located near the households.
Figure 2. Sampling fish by using cast net.
Shown a throw of cast net when sampling fish from a grow-out pond in Nam Dinh.
Figure 3. Map of study area.
Nam Dinh province is located in the Southern Red River Delta, bordered by Ha Nam province to the North, the Gulf of Tonkin in the South-East, Thai Binh province to the East and Ninh Binh province on the West. Nghia Lac and Nghia Phu communes belong to Nghia Hung district, Nam Dinh province.
References
- WHO. 2004. pp. 1–58. Report of Joint WHO/FAO workshop on food-borne trematode infections in Asia, Ha Noi, Vietnam.
- Chai JY, Murrell KD, Lymbery AJ. Fish-borne parasitic zoonoses: Status and issues. International Journal for Parasitology. 2005;35:1233–1254. - PubMed
- Rim H, Hillyer G, V, Hopla C. Clonorchiasis. Parasitic zoonoses Volume 3. 1982:17–32.
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