Prevalence and risk factors related to Fasciola spp. transmission in Northern Vietnam: A cross-sectional study in multiple hosts
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Background
Fascioliasis, caused by Fasciola hepatica and Fasciola gigantica , is a global veterinary problem in livestock and an emerging zoonotic disease in various countries. Here we present prevalence estimates of Fasciola spp. in all hosts involved in the life cycle and identified risk factors associated with Fasciola transmission in northern Vietnam.
Methodology/Principal findings
We conducted a cross-sectional survey in a community in Nghe An province where fascioliasis is endemic and inhabitants commonly consume raw vegetables. Applying a simple random and cluster sampling approach, we collected 1,137 stool and 1,390 blood samples from 1,396 human participants. From 664 buffaloes and cattle, we collected 656 fecal and 534 blood samples. We also collected 330 lymnaeid snails and 233 water plant samples. Human and animal fecal samples were examined by copro-microscopy, while blood samples were screened by ELISA to detect Fasciola serum antibodies. We examined infections in snails using PCR and metacercariae on water plants deploying an in-house technique. Descriptive analysis and logistic regression models were applied to estimate the prevalence of and risk factors for Fasciola infections. While the prevalence of Fasciola infections was very low in humans (0% by copro-microscopy; 0.07% by ELISA), it was high in animals (52% by copro-microscopy; 54% by ELISA). In the multivariable analysis, age was the only factor associated with Fasciola infections in animals. Fasciola could not be detected in any of the sampled water plants or lymnaeid snails..
Conclusion/Significance
This study indicated a high prevalence of Fasciola infections in animals and a very low prevalence in humans in a rural community in northern Vietnam. It is recommended to implement a control program to reduce the infection rate in buffaloes and cattle. Furthermore, health education activities for livestock owners should be carried out in Fasciola endemic areas.
Author Summary
Fascioliasis is a parasitic disease, caused by the flatworms Fasciola hepatica and Fasciola gigantica , affecting the liver of livestock and humans. Although human fascioliasis is known to occur worldwide, it mainly affects the poorest communities in rural areas across subtropical and tropical countries, with recent emergence in countries such as Vietnam. We conducted a cross-sectional survey on Fasciola spp. infections in different hosts (e.g., humans, buffaloes, cattle, water plants, and snails) in a rural community in northern Vietnam. Our results showed a high prevalence of fascioliasis in livestock, and a very low prevalence in humans, in a rural community in Nghe An province. Fasciola could not be detected in the sampled lymnaeid snails and water plants. In livestock, the occurrence of Fasciola infection was associated with increasing age. Treatment of the community livestock population as well as specific awareness campaigns for livestock owners are suggested to reduce disease transmission.
