Hepatitis E Seroprevalence and Detection of Genotype 3 Strains in Domestic Pigs from Sierra Leone Collected in 2016 and 2017

Abstract

Hepatitis E virus (HEV) is the main cause of acute hepatitis in humans worldwide and is responsible for a large number of outbreaks especially in Africa. Human infections are mainly caused by genotypes 1 and 2 of the genus Paslahepevirus, which are exclusively associated with humans. In contrast, viruses of genotypes 3 and 4 are zoonotic and have their main reservoir in domestic and wild pigs, from which they can be transmitted to humans primarily through the consumption of meat products. Both genotypes 3 and 4 are widespread in Europe, Asia, and North America and lead to sporadic cases of hepatitis E. However, there is little information available on the prevalence of these genotypes and possible transmission routes from animal reservoirs to humans in African countries. We therefore analysed 1086 pig sera collected in 2016/2017 in four districts in Sierra Leone for antibodies against HEV using a newly designed in-house ELISA. In addition, the samples were also analysed for HEV RNA by quantitative real-time RT-PCR. The overall seroprevalence in Sierra Leone was low with only 44 positive sera and a prevalence of 4.0%. Two serum pools were RT-PCR-positive and recovered partial sequences clustered into the genotype 3 (HEV-3) of the order Paslahepevirus, species Paslahepevirus balayani. The results are the first evidence of HEV-3 infection in pigs from Sierra Leone and demonstrate a low circulation of the virus in these animals to date. Further studies should include an examination of humans, especially those with close contact with pigs and porcine products, as well as environmental sampling to evaluate public health effects within the framework of a One Health approach.

Keywords: Sierra Leone; genotype 3; hepatitis E virus; pigs.

Figure 1

Geographical distribution of pig sera sampled in 2016 (orange coloured) and 2017 (blue coloured) in Sierra Leone. Determined HEV antibody-positive sera and viral RNA are displayed in corresponding symbols (https://d-maps.com/carte.php?num_car=27754&lang=de, accessed on 10 March 2024).

Figure 2

Neighbour-joining phylogenetic tree based on partial RNA-dependent RNA polymerase (A) and methyltransferase (B) sequences. Red boldface letters indicate pig sequences from serum pool 62 and serum pool 63, respectively. Scale bar indicates mean number of substitutions per site.