Zoonotic Transmission of the Hepatitis E Virus

Segment Description: Kenneth E. Sherman, MD, Gould professor of medicine, University of Cincinnati College of Medicine, discusses the zoonotic hepatitis E virus and about the first reported case of rat-to-human transmission.

Interview transcript (modified slightly for readability):

I think it’s important to first redefine hepatitis E and its risk. When hepatitis E was discovered, it was thought to be a hepatitis A-like disease—fecally-orally transmitted, present mostly in developing countries with a poor sanitation system and pure water purification systems. Indeed, epidemic outbreaks in developing countries still occur and are quite common; we see them in the setting of refugee camps, there were major outbreaks in Chad during this past year.

But there is another form of hepatitis E, a zoonotic form of hep E, which is very poorly recognized and occurs or appears to be a huge and important disease that is underrecognized in developed and Western countries, as well as other parts of the world.

This disease is spread in animal populations and is thought to be acquired when humans come in contact with animals or eat animal products that lead to infection. In fact, most people don’t realize that approximately 10% to 15% of the US population—with the highest prevalence in the Midwest—has been infected with hepatitis E, primarily acquired through contact with swine and perhaps some percentage acquired through eating meat or handling deer in the process of hunting and then consuming the venison.

Various strains of hep E are ubiquitous in the animal world and transmission from one species to another is actually very common as one moves up the food chain. In fact, bears have clearly been shown to be infected with rat hepatitis E, presumably because they eat rats.

The group of patients at highest risk for zoonotic-acquired hepatitis E infection—both acute infections, and actually, in many cases, progressing to chronic hepatitis E—are immunosuppressed patients, including those that have received liver, solid organ transplants, and are on lifelong immunosuppression. Because those patients not only get hepatitis E, but rather than having a mild illness or an unrecognized illness, they get an illness and then they develop a chronic disease state, they do not clear the virus, leading to progressive injury in their liver—this is well recognized.

The recent report of spread of a rat virus to humans in a liver transplant recipient doesn’t surprise me at all. I think the key question that has not been asked is: Did this person consume rats?

I think we need to learn more about this case and I also think we need to move away from thinking about hepatitis E as an epidemic water-borne disease—especially in western countries—and think about it as a zoonotic, animal-associated and acquired disease process.