Prevalence and risk factors related toFasciolaspp. transmission in Northern Vietnam: A cross-sectional study in multiple hosts

Abstract

BackgroundFascioliasis, caused byFasciola hepaticaandFasciola gigantica, is a global veterinary problem in livestock and an emerging zoonotic disease in various countries. Here we present prevalence estimates ofFasciolaspp. in all hosts involved in the life cycle and identified risk factors associated withFasciolatransmission in northern Vietnam.Methodology/Principal findingsWe 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 detectFasciolaserum 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 forFasciolainfections. While the prevalence ofFasciolainfections 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 withFasciolainfections in animals.Fasciolacould not be detected in any of the sampled water plants or lymnaeid snails..Conclusion/SignificanceThis study indicated a high prevalence ofFasciolainfections 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 inFasciolaendemic areas.Author SummaryFascioliasis is a parasitic disease, caused by the flatwormsFasciola hepaticaandFasciola 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 onFasciolaspp. 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.Fasciolacould not be detected in the sampled lymnaeid snails and water plants. In livestock, the occurrence ofFasciolainfection 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.