Risk factors for Entamoeba histolytica infection in an agricultural community in Hanam province, Vietnam

Phuc Pham Duc,Jan Hattendorf,Jakob Zinsstag,Peter Odermatt,Phung Dac Cam,Hung Nguyen-Viet

doi:10.1186/1756-3305-4-102

Abstract

BackgroundEntamoeba histolytica is an important protozoan intestinal infection in resource-poor settings, including Vietnam. The study objective was to assess risk factors of E. histolytica infection in a community in Vietnam, where wastewater and human excreta are used in agriculture. A case-control study was conducted among residents of Hanam province, Northern Vietnam. Cases (n = 46) infected with E. histolytica and non-infected controls (n = 138) were identified in a cross-sectional survey among 794 randomly selected individuals and matched for age, sex and place of residence. Potential risk factors including exposure to human and animal excreta and household wastewater were assessed with a questionnaire.ResultsPeople from households with an average socio-economic status had a much higher risk of E. histolytica infection (odds ratio [OR]=4.3, 95% confidence interval [CI]: 1.3-14.0) compared with those from households with a good socioeconomic status. Those individuals who never or rarely used soap for hand washing had a 3.4 times higher risk for infection (OR=3.4, 95% CI: 1.1-10.0), compared to those who used always soap. In contrast, none of the factors related to use of human or animal excreta was statistically significant associated with E. histolytica infection. People having close contact with domestic animals presented a greater risk of E. histolytica infection (OR = 5.9, 95% CI: 1.8-19.0) than those without animal contact. E. histolytica infection was not associated with direct contact with Nhue river water, pond water and household's sanitary conditions, type of latrine or water source used.ConclusionsOur study suggests that in settings where human and animal excreta and Nhue River water are intensively used in agriculture, socio-economic and personal hygiene factors determine infection with E. histolytica, rather than exposure to human and animal excreta in agricultural activities.

Highlights

Entamoeba histolytica is an important protozoan intestinal infection in resource-poor settings, including Vietnam
We have studied risk factors associated with E. histolytica infection in a semi-rural community where human and animal excreta are intensively used as fertiliser in agriculture and where household wastewater is directed into irrigation channels
We identified lower economic status of households (OR = 4.3), poor hand washing practices after work (OR = 3.4) and close contact with animals in the household (OR = 5.9) as major risk factors for E. histolytica infection

Summary

Introduction

Entamoeba histolytica is an important protozoan intestinal infection in resource-poor settings, including Vietnam. The study objective was to assess risk factors of E. histolytica infection in a community in Vietnam, where wastewater and human excreta are used in agriculture. Amoebiasis caused by the intestinal parasite Entamoeba histolytica, has an estimated worldwide prevalence of 500 million infected people and is responsible for 40,000 100,000 deaths each year It is an important health problems, especially in developing countries [1,2]. The rate of infection by E. histolytica differs among countries, socio-economic and sanitary conditions and populations [4] It is highly endemic throughout poor and socio-economically deprived communities in Wastewater and human and animal excreta are used as fertilizer for a wide variety of crops, and 10% to 30% increases in crop yields have been reported [7].

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