Contribution of zoonotic and WASH-related transmission routes to the burden of Hepatitis E in Ghana

Abstract

Hepatitis E virus (HEV) is a significant cause of zoonotic, enterically transmitted hepatitis associated with sporadic and acute cases in humans worldwide. Hepatitis E affects poor populations severely in many developing nations as a neglected tropical disease associated with water, sanitation, and hygiene (WASH). Environmental risk factors for spreading the virus to humans are pervasive in Ghana, with a low sanitation coverage of 15% and an open defaecation rate of 19%, including widespread faecal contamination of drinking water. Additionally, the free range system is commonly used to keep domestic pigs, the primary hosts of HEV, in major pig production communities. However, the burden of the disease and the contribution of these prevailing environmental conditions to infection transmission have yet to be well known. The study aimed to determine the public health burden of Hepatitis E and the role zoonotic and WASH-related pathways play in transmitting the infection in Ghana.

A systematic review was conducted to determine the burden and epidemiology of Hepatitis E in sub-Saharan Africa. The findings demonstrate that HEV is endemic in Sub-Saharan Africa and is associated with significant hepatitis cases and poor pregnancy outcomes. Due to the use of serological techniques in most studies, it is challenging to determine the actual burden of active infection. There has been relatively little investigation into the sources of contamination and the transmission channels. Although there appear to be some indications of zoonotic transmission of infections, further research is required.

A cross-sectional seroepidemiological study was conducted between 2019 and 2021 to determine Ghana's public health burden of HEV infection. The study included sixteen (16) communities in eight (8) districts and ten (10) antenatal clinics. A total of 1,365 community members, 105 pig farmers, 1,000 pregnant women, and 474 pigs were sampled for the study. To identify HEV infection, virological and serological methods were both used. Additionally, the study examined faecal coliform contamination in 52 households and 28 community drinking water samples using the pour plate method.

Overall seroprevalence and prevalence were 12.4% and 0.7% amongst community members and 15.2% and 2.9% amongst pig farmers, respectively. Compared to other community members, pig farmers had a much higher prevalence: 𝑥�2(1) = 5.813; p = 0.0159). Age, gender, and region of residence were significant demographic risk factors for HEV IgG seroprevalence. Only the type of drinking water used was a significant behavioural risk factor for HEV IgG seroprevalence. There is evidence of zoonotic transmission from pigs to humans (pig farmers) and vice-versa as a result of open defaecation practices by humans. In general, both the zoonotic and WASH pathways of HEV transmission are essential, with a zoonotic risk associated with pig handlers and a WASH-related risk amongst the general population. An overall HEV IgG seroprevalence of 8.3% and antigen prevalence of 1.0% were recorded in pregnant women. The disease burden is low and similar to those in developing countries and is not the cause of poor pregnancy outcomes.

In pigs, the seroprevalence and the antigen prevalence were 62.4% and 5.5%, respectively. A significantly higher seroprevalence was found in free range pigs (88.3%) compared to confined pigs (6.7%); 𝑥�2(1) = 55.504; p < 0.0001) in the Volta Region. Open defaecation by humans and free range pig management are the major drivers of HEV infection in pigs. Infection is high in confined pigs as a result of poor management practices. Therefore, confining pigs alone will not control HEV infection amongst pigs unless it is backed with proper management practices by ensuring that breeding stocks are HEV-free. Pigs play a major role as reservoir hosts of the virus in Ghana.

The microbial quality results showed widespread contamination of community and household drinking water, with 82.1% and 92.3% of community and household water contaminated, respectively. A significantly higher proportion of water samples were contaminated at the household level (67.6%) compared with the community level (32.3%); x2= 8.803; p = 0.003.

The data provided in this research will be fundamental to raising awareness about the need for further research into the dynamics of HEV in Ghana and improving control measures. While a One Health approach is important for implementing immediate prevention and control, a worldwide approved effective vaccine is likely required before HEV eradication can be considered a practical goal.