Rare hepatitis strain infects human

Rat hepatitis E virus linked to severe acute hepatitis in an immunocompetent patient. Andonov A*, Robbins M, Borlang J*, Cao J*, Hatchette T, Stueck A, Deschaumbault Y*, Murnaghan K, Varga J*, Johnston B. J Infect Dis 2019 Jan 11. doi: https://doi.org/10.1093/infdis/jiz025

In recognition of World Hepatitis Day (July 28), this science story highlights the use of expanded laboratory testing that enabled the diagnosis and characterization of a novel strain of Hepatitis E virus. This new knowledge can be used to better detect, monitor and understand this infectious disease.

What was known about this area prior to your work, and why was the research done?

Hepatitis E virus (HEV) is a major public health concern in developing countries where the primary transmission is via contaminated water. Zoonotic HEV cases, with pigs representing the main animal reservoir of infection, have been increasingly described in Europe, Japan, and the United States. Recent serologic data suggest that humans can also be infected with rat HEV. This research both confirmed and described a severe acute human case of hepatitis that was caused by a novel strain of rat HEV.

What are your most significant findings from this work?

This work identified and characterised an unusual acute hepatitis infection, using a broadly reactive polymerase chain reaction (PCR) genomic sequencing method. The diagnosis of a novel strain of rat HEV would have been missed using commercially available diagnostic tests for HEV human infection. Further, it was found that this strain of rat HEV had a considerably different genomic sequence compared to other rat HEV strains, therefore representing a novel genotype.

This is the second recording of human infection with rat HEV just months after the first ever case was identified in Hong Kong. The Hong Kong patient lived in rat-infested housing and was immunosuppressed, which may have facilitated the interspecies transmission. However, the rat HEV infection in this study occurred in a previously healthy person with no direct link to rats. For this reason, a secondary and still-unknown route of transmission may be involved.

What are the implications or impact of the research?

It is possible that rat HEV is an under recognized cause of human hepatitis. Further studies are necessary to elucidate its potential risk and mode(s) of transmission. Since routinely used serological and molecular diagnostic assays for HEV hepatitis in humans miss rat HEV infection, it may be more prevalent and have a greater public health impact than previously considered.

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