Abstract
BackgroundHepatitis E virus (HEV) is a major cause of human hepatitis worldwide. Zoonotic genotypes of the virus have been found in diverse animal species with pigs playing a major role. Putative risk of zoonotic infection from livestock particularly swine in Sub-Saharan Africa including Ghana is poorly understood due to scarcity of available data, especially HEV sequence information.MethodsSerum samples were collected from cattle, sheep, goats and pigs from Kumasi in the Ashanti region of Ghana. Samples were subjected to nested RT-PCR screening and quantification of HEV RNA-positive samples using real-time RT-PCR and the World Health Organization International Standard for HEV. Testing of all pig samples for antibodies was done by ELISA. Sanger sequencing and genotyping was performed and one representative complete genome was generated to facilitate genome-wide comparison to other available African HEV sequences by phylogenetic analysis.ResultsA total of 420 samples were available from cattle (n = 105), goats (n = 124), pigs (n = 89) and sheep (n = 102). HEV Viral RNA was detected only in pig samples (10.1%). The antibody detection rate in pigs was 77.5%, with positive samples from all sampling sites. Average viral load was 1 × 105 (range 1.02 × 103 to 3.17 × 105) International Units per mL of serum with no statistically significant differences between age groups (≤ 6 month, > 6 months) by a T-test comparison of means (t = 1.4272, df = 7, p = 0.1966). Sequences obtained in this study form a monophyletic group within HEV genotype 3. Sequences from Cameroon, Ghana, Burkina Faso and Madagascar were found to share a most recent common ancestor; however this was not the case for other African HEV sequences.ConclusionHEV genotype 3 is highly endemic in pigs in Ghana and likely poses a zoonotic risk to people exposed to pigs. HEV genotype 3 in Ghana shares a common origin with other virus strains from Sub-Saharan Africa.
Highlights
Hepatitis E virus (HEV) is a major cause of human hepatitis worldwide
We applied a heminested reverse transcriptase (RT)-Polymerase Chain Reaction (PCR) using broadly reactive primers targeting a 338-nucleotide fragment of the Ribonucleic Acid (RNA)-dependent RNA polymerase (RdRp) gene of HEV with the Superscript III one-step RT-PCR kit (Thermo Fischer, MA, United States of America (USA))
Testing for HEV RNA and antibodies RT-PCR testing of all livestock serum samples, resulted in 9 swine serum samples identified to be positive for HEV viral RNA, representing 10.1% of the collected swine samples
Summary
Hepatitis E virus (HEV) is a major cause of human hepatitis worldwide. Zoonotic genotypes of the virus have been found in diverse animal species with pigs playing a major role. Major risk factors for zoonotic transmission of HEV include contact with infected animals especially pigs and consumption of undercooked animal products [4, 7]. High detection rates of HEV RNA in pigs at slaughter have been demonstrated in different countries with up to 41% in Canada, and up to 44% in the UK [8,9,10,11]. This places people like pig handlers and abattoir workers at high risk of infection [12]
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