Relatives of all forms of hepatitis virus (A, B, C, D and E) are found in animals ranging from fish to deer. However, hepatitis E virus (HEV) is the only form considered zoonotic, meaning it can pass from animals to humans. A recent study in Nature Communications reviewed scientific evidence on Rocahepevirus ratti, or rat HEV, including its epidemiology, diagnosis, treatment and prevention.

 

HEV causes acute inflammation of the liver and is transmitted via oral-anal contact, typically through contaminated water. Infection usually resolves on its own within two to six weeks, but in some cases, especially for those with compromised immune systems, it can lead to fulminant hepatitis, or acute liver failure, which is life-threatening. In pregnancy, HEV can be transmitted to the fetus, leading to pregnancy complications (stillbirth, preterm labor or low birth weight). One in four pregnant women die if they contract HEV during the third trimester, according to the Cleveland Clinic.

 

RatHEV was detected in rats across Europe, Asia and North America, with the highest prevalence in urban areas in subtropical Asia and southern Europe. The virus is spread primarily though rat feces, and experimental infections in nonhuman primates and pigs showed virus RNA in feces for two to three weeks after an infection subsided, leaving a large window for viral shedding and spread. When rat feces carrying HEV contaminate water sources (treatment plants, surface waters and more), humans may come into indirect contact with the virus.

 

Symptoms of ratHEV typically appear two to eight weeks after infection and are very similar to HEV symptoms, which include jaundice (yellowing of skin or eyes), fever, nausea, abdominal pain and fatigue. Commercial ratHEV tests are not widely available, making diagnosis a challenge, but blood and stool tests can detect ratHEV RNA to confirm infection.

 

Currently, an HEV vaccine is available only in China. Research suggests, however, that past HEV infection can partially protect people against ratHEV, but investigators emphasize that clinical efficacy data are lacking.  

 

With only 51 cases of ratHEV in humans to date, the understanding of its impacts on human health are still unclear.

 

“To address these gaps, international coordination will be essential to develop validated diagnostics, harmonize surveillance protocols and strengthen early detection of emerging zoonotic threats,” wrote the researchers.