This is the first study in Ghana reporting ALT, AST values and risk factors associated with HEV infection in persons who work with pigs, and demonstrates the high prevalence of and the considerable potential for the transmission of HEV infection in pig farms in Ghana. Although there is no report from the Ministry of Health, Accra, Ghana indicating that Ghana is an endemic area for hepatitis E, this study found very high overall prevalence rates (34.84%) of HEV antibody. In addition, the study found significantly high ALT and AST levels >3× the expected maximum among persons occupationally exposed to pigs, suggesting the possibility of subclinical infections in the country. Further studies with a larger number of pig handlers will be necessary to draw a definitive conclusion. Moreover, additional studies need to be done to isolate both the pig and human HEV strains in Ghana and determine the genomic relationship between them if both the human and pig HEV are isolated.
The risk of HEV infection correlated with length of time employed, close contact with animals or animal waste, such as cleaning barns or assisting sows at birth, butchering pigs, consumption of alcohol, and having piped water in homes and/or on the farms. The finding of higher HEV antibody prevalence in persons who work with pigs in Ghana is consistent with literature, and is widely attributable to work-related behaviours practised on the farm settings, although transmission of HEV has also been documented among individuals outside the farm setting and persons who are not occupationally exposed to pigs [18–22]. The overall seroprevalence of HEV infection among persons who work with pigs in Ghana (34.84%) is higher than the results of similar studies in persons who work with pigs in Taiwan  (26.7%) but comparable to the reported seroprevalence of 51.1% in persons who work with pigs in Moldova . The increased seroprevalence of HEV in persons who work with pigs (34.84% %) in Ghana suggests that HEV may be widespread in pig populations in the country and therefore reasonable to speculate that HEV may circulate in the general population. In addition, because the virus is transmitted through the faecal-oral route, transmission of HEV is greatly dependent on the sanitary conditions under which the pig handlers work. In Ghana, there are great social differences and sanitary conditions are quite precarious in many areas. The sanitary conditions at the work place during the period of study were very deplorable and all the farms were situated in densely populated areas where the animals share their habitat with humans. Of interest, persons who work with pigs that had water piped into their homes and/or on the farms had higher anti-HEV reactivity than those who do not have piped water into their homes and/or on the farms (33.43%; 118 out of 353 vs. 0.14%; 5 out of 353%, respectively; Table 6). This finding is not surprising since most of the water delivery pipes are broken and/or exposed and as such the water may have been easily contaminated with faecal effluent in the locality. Moreover, hand-washing facilities are not easily available on the farms.
Another finding of interest reported herein in our study is that anti-HEV prevalence was significantly higher (P < 0.001) among persons who had been working with pigs in the same farm setting for less than 6 months compared to those who had been working in the same farm setting for more than 6 months (63.12%, 89 out of 141 vs, 16.04%, 34 out 212 respectively). The reason(s) for this disparity cannot be discerned from our study. However, it was observed that newly recruited individuals spend more time cleaning barns and assisting sows at birth, and this perhaps may have accounted for the high seroprevalence rate of HEV infection. Further studies need to be done to define the high prevalence of anti-HEV antibodies in such population.
Of particular note, pig handlers studied who tested positive for antibodies to IgG anti-HEV or IgM anti-HEV had ALT (210.17 ± 11.64 IU/L, 200.97 ± 10.76, IU/L, respectively) levels >3× the expected maximum. A similar pattern was noted in serum AST levels among pig handlers. Levels 3× the expected maximum were found in pig handlers studied who tested positive for antibodies to IgG anti-HEV (AST, 127.18 ± 11.12) or IgM anti-HEV (AST, 120.00 ± 15.96). Interestingly, among the different age groups, pig handlers, 26-30 years of age, had higher levels of ALT and AST (data not shown).
Growing evidence suggest that elevated ALT and AST levels are associated with recent acute HEV infection [14–17, 23]. Similar results were obtained in our study and thus provided a unique opportunity to diagnose asymptomatic and symptomatic HEV infection in an occupationally exposed group. The presence of seropositive IgM/IgG anti-HEV and increased levels of ALT and AST usually indicate recent HEV infection  and may signify recent introduction of HEV into these farms. There is therefore the need to investigate other farms around these locations to ascertain whether there had been any earlier infections among farm workers. There is also the need for further studies to define the clinical and epidemiological importance and pathogenesis of HEV infection in this population.
Another finding of interest reported herein in our study is that anti-HEV prevalence was associated with consumption of alcohol (OR 4.91: 95% CI 2.65-9.10) among persons who had been working with pigs. Although excess alcohol consumption could compromise hepatic function and predispose pig handlers to HEV infection as suggested by our study, consumption of alcohol may not be probably linked to exposure to HEV infection. However, from our studies it is also possible that excess consumption of alcohol may have resulted in lack of self control therefore leading to higher risk behaviour of HEV infection. Further studies need to be conducted to define the link between alcohol consumption and HEV infection among persons who work with pigs.
The small sample size and our inability to test for anti-HEV reactivity in pigs, may be the limitations of this study. However, the detection and prevalence of HEV infection coupled with significantly high values of ALT and AST in persons who work with pigs in Ghana may reflect the prevalence of past and recent HEV infections among pig handlers in the country. Further studies need to be done to define clearly the natural history of HEV infection and transmission in Ghana in order to effectively control and prevent HEV zoonosis.
The results reported herein have significant implications for veterinarians, public health officials, persons who work with pigs and farm managers, and suggest urgent need for the introduction of policies to prevent the transmission of HEV on the farms and the general population. These policy strategies must include increasing education of persons who work with pigs about the need for HEV testing and prevention in infected pig handlers. The implementation of a HEV infection prevention programme in pig farms in Ghana should be seen as an opportunity to improve the health status of the infected persons who work with pigs and to prevent further transmission of HEV, within and without the farm settings. The argument for HEV testing among persons who work with pigs in Ghana is compelling, because of the precarious sanitary conditions in most urban and rural areas, increased incidence of acute viral hepatitis without a defined aetiology (unpublished data, Department of Medicine and Therapeutics, KBTH), and the high infant and maternal mortality. Our findings re-emphasize the suggestion that targeting high-risk pig handlers or universal testing in high prevalence areas, which includes Ghana, could identify most pig handlers, pregnant women, and blood donors infected with HEV at a relatively low cost [1, 23].