Prevalence of Hepatitis E genotype 3 among liver disease patients in Southwestern Nigeria

Abstract

Owing to its high mortality rate, viral hepatitis is a major public health problem, especially in low-income countries. In Africa, hepatitis B virus (HBV) and hepatitis E virus (HEV) are highly endemic, and HBV/HEV coinfections, which are associated with more severe liver disease and poor outcomes, are common. HEV genotypes 1 and 2 have been associated with large human outbreaks, while 3 is known to circulate in pigs and sporadically in humans. In this study, the prevalence of HBV and HEV among individuals with acute or chronic liver diseases in Osun State, Southwest Nigeria, was analyzed. One hundred plasma samples from liver disease patients attending Ladoke Akintola University Teaching Hospital were analyzed for the presence of anti-HEV antibodies and hepatitis B surface antigen (HBsAg) via ELISA, and HEV RNA and HBV DNA were analyzed via RT‒PCR. Virus genotyping was performed by sequencing and subsequent phylogenetic analysis. Overall, 50 individuals (50%) were positive for HBsAg, of which 14 (28%) also tested positive for HBV DNA. Two individuals (2%) had occult HBV infection. Most HBV strains were genotype E, except for two genotype A (A2 and A3). Anti-HEV antibodies were detected in eight individuals (8%), with one (1%) being positive for anti-HEV IgM and seven (7%) for anti-HEV IgG. Nine (9%) samples had detectable HEV RNA, with one being HEV-3; a rare occurrence in Nigeria. Coinfection with HBV/HEV was detected in seven (7%) individuals. The prevalence of HEV in Nigeria is low, but considering the high prevalence of HBV and the possible complications due to HEV coinfection or superinfection, HEV screening and HBV vaccination targeting high-risk populations are emphasized.

Keywords: Coinfection; HBV; HEV; Liver disease; Nigeria.

Fig. 1

Flow diagram showing a summary of the number of patients tested and the detection outcomes

Fig. 2

Phylogenetic tree constructed via partial coding of the S gene of HBV isolates (liver disease patients). The evolutionary history was inferred via maximum likelihood based on the Tamura‒Nei model. Phylogenetic reconstruction of the Pol region of sequences revealed that the HBV isolates clustered in the HBV-E branch, and the HBV sequences were compared with reference sequences representing 8 HBV genotypes (NCBI-GenBank accession numbers denoted). HBV isolates from this study NG19-XX (accession numbers PP983217–PP983227). Evolutionary analysis was conducted in MEGA 7.0.26

Fig. 3

Reconstructed phylogenetic tree using the partial ORF 2 of HEV isolates (liver disease patients). The evolutionary history was inferred via maximum likelihood based on the Tamura‒Nei model. Phylogenetic reconstruction of the ORF2 region of the sequences revealed that the HEV isolate (NG19-06, Accession no. MT942691) clustered in the HEV genotype 3 branch, and the HEV sequences were compared with 30 reference sequences of HEV genotypes 1-7 (NCBI-GenBank accession numbers denoted). Evolutionary analyses were conducted in MEGA7.0.26