Camels gained attention since the discovery of MERS-CoV as intermediary hosts for potentially epidemic zoonotic viruses. Epidemiological studies on hepatitis E virus (HEV) seroprevalence in pregnant Ethiopian women led to detection of HEV-specific antibodies in Ethiopian Dromedary camels (DCs). Several other studies have demonstrated HEV antibodies in dromedary camels in Africa and the Middle East. As a novel HEV genotype, the Dromedary camel hepatitis E virus (DcHEV), was first reported from the UAE in a transplant patient with chronic hepatitis and was linked to consuming camel milk and meat. Recent studies of DcHEV in DCs from UAE have shown DcHEV-specific antibodies and presence of DcHEV viral genomes. Saudi Arabia is the world’s largest importer of DCs from African countries. Whilst serological studies have detected DcHEV antibodies in Saudi DCs imported from Africa, the presence of viral RNA remains to be defined. Detailed molecular and phylogenetic characterization of the DcHEV circulating in DCs in the country is critically important for surveillance and evolution of human infections, and design of appropriate control and preventive measures. A team from King Abdulaziz University, Saudi Arabia, led by Prof. Esam Azhar have perused this endeavour.
Up to date, this is the largest and most comprehensive study of surveying DcHEV in domestic and imported dromedary camels from Africa. Domestic DCs from Saudi Arabia had higher prevalence of DcHEV RNA than imported camels from Africa. This might reflect the younger age of domestic camels where infection acquired early in life had been cleared DcHEV. Phylogenetic analysis of the viral RdRp sequences identified infection with HEV genotype 7. Compared to the HEV genotype 7 sequence KJ496144, the two full genome sequences from this study showed 242 nucleotide variations including 24 nonsynonymous mutations leading to the amino acid changes. Sequences from domestic camels formed a separate cluster compared to published sequences from Kenya, Somalia, and UAE. The sequences of imported camels clustered with one DcHEV isolate previously reported from UAE indicating a possible common source of animal infection. Both domestic and imported sequences clustered away from isolates reported from Pakistan. Further investigation is needed to clarify the significance of these differences.
DcHEV was detected in 1.77% of samples with higher positivity in domestic DCs. These results provide evidence for the presence of DcHEV in both domestic and imported camels from Africa with evolving genomic changes. All positive imported dromedaries were from Sudan with age declining prevalence. Any change in transmissibility and virulence of DcHEV in DCs would affect the risks of spread to humans and its potential impact on national and regional public health security. Further surveillance studies are required to identify the role of these DcHEV amino acid changes in the course of the disease and viral transmission. Further clinical, serological, molecular and epidemiology investigations of DcHEV in human populations in the Middle East and Africa are needed to define and monitor the potential threat of DcHEV to Middle eastern and global public health security in light of 10 million pilgrims who visit Saudi Arabia every year.
Read the full article (Sci Rep. 2022 Apr 29;12(1):7005) https://www.nature.com/articles/s41598-022-11208-6
