In a rare finding, researchers in France discovered five cases of human infection with a hepatitis E virus strain found in rabbits.
The researchers said they could not identify how the patients — who were not all from the same region — were infected with the HEV3-ra strain but suspect it might have been via waterborne transmission because the strain was found in environmental samples.
“None of the patients had direct contact with rabbits, suggesting foodborne or waterborne infections,” Florence Abravanel, PharmD, PhD, assistant professor in the virology department at Toulouse University Hospital in Toulouse, France, and colleagues wrote in Emerging Infectious Diseases.
Researchers in France discovered five patients infected with a hepatitis E virus strain found in rabbits.
According to Abravanel and colleagues, reports of hepatitis E virus (HEV) infection in humans are becoming more frequent. The CDC reports that there are an estimated 20 million HEV infections worldwide each year, with around 3.3 million symptomatic cases and 56,600 related deaths.
According to Abravanel and colleagues, infections with HEV3 are generally asymptomatic and self-limiting, although symptomatic acute hepatitis can develop in some patients, mostly older men, and the infections can become chronic in immunocompromised patients.
HEV3-ra is just one of three clades of the HEV3 genotype, the most prevalent genotype in industrialized countries, Abravanel and colleagues explained. According to their report, the other two are found in humans and pigs. Human infections are mostly acquired through direct contact with infected pigs, they said.
According to the report, HEV3-ra has been found in farmed and wild rabbits and one pet rabbit. However, only one case of human infection had been documented before Abravanel and colleagues discovered five cases while analyzing 919 HEV strains in the French National Reference Center for HEV that were obtained from patients between 2015-2016.
Using RT-PCR, Abravanel and colleagues discovered that 904 of the 919 patients were infected with an HEV3 strain, including the five patients with HEV3-ra. All five patients with HEV3-ra were men with a median age of 52 years.
Abravanel and colleagues described the patients:
- They were from different regions — three lived in southern France and two in northern France.
- Four were immunocompromised, including two solid organ transplant recipients.
- None reported any direct contact with rabbits.
- Two had eaten well-cooked rabbit products; two drank tap water, three drank only bottled water; one had a vegetable garden.
Abravanel and colleagues speculated that HEV3-ra might be less infectious than other HEV3 strains, or that the rarity of human infections could be a result of relatively few people consuming rabbit products. However, they said more research is needed to answer the remaining questions.
“Our findings emphasize the zoonotic risk for HEV3-ra and expand the spectrum of potential sources of human infection,” they wrote. “The route by which HEV3-ra is transmitted to humans needs to be investigated. Longitudinal study of HEV diversity is also needed to assess trends over time.” – by Gerard Gallagher
Abravanel F, et al. Emerg Infect Dis. 2017;doi:10.3201/eid2307.170318.
Disclosure: The researchers report no relevant financial disclosures.