Prevalence and risk factors related to Fasciola spp. transmission in north-Central Vietnam: A cross-sectional study in multiple host and environmental compartments

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 host and environmental compartments involved in the life cycle and identified risk factors associated with Fasciola transmission in a rural community in north-central Vietnam.

METHODOLOGY/PRINCIPAL FINDINGS: We conducted a cross-sectional survey in a community in Nghe An province where fascioliasis is reported to be endemic and inhabitants commonly consume raw vegetables. Applying a simple random and cluster sampling approach, we collected 1137 stool and 1390 blood samples from 1396 human participants. From 664 buffaloes and cattle, we collected 656 fecal and 534 blood samples. We also collected 340 lymnaeid snails and 233 water plant samples. Human and livestock 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 contamination of 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 livestock (51.5% by copro-microscopy; 54.1% by ELISA). In the multivariable analysis, age was the only factor associated with Fasciola infections in livestock. 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 livestock and a very low prevalence in humans in a rural community in north-central 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.