Researchers report first evidence of Seoul hantavirus in wild rats in the Netherlands

In a paper just published in the peer reviewed journal Infection, Ecology & Epidemiology, researchers report discovering the first evidence of Seoul hantavirus (SEOV) in the wild rat population in the Netherlands. The discovery comes on the heels of similar ones in France, Belgium and the United Kingdom in recent years, and has some researchers concerned about the potential spread of the virus to humans.

In humans, the virus can cause hemorrhagic fever and kidney failure, and has a mortality rate of between one and two percent.

Åke Lundkvist is a professor at the Department of Medical Biochemistry and Microbiology, Zoonosis Science Centre at Uppsala University in Sweden; and last author of the paper. He has been studying hantavirus for 25 years. Lundkvist believes this discovery could be indicative of something more substantial at play in the wild rat population.

"Though there are only a handful of cases on record where humans have been infected from nature, as opposed to via a pet or laboratory, I believe this discovery points to the need for a greater research effort," said Lundkvist, "For what could be undiscovered cases."

"What our findings indicate is the need for a much more thorough investigation of the virus in the rat population, and likewise, a thorough investigation into possible human cases of the virus that might have gone unnoticed."

Of the documented variants of hantaviruses, SEOV has been reported in previous research as the only one with potential world-wide distribution; this is due to the ubiquitous occurrence of its hosts, the brown and the black rat, which can be found in urban areas, farmlands as well as in nature preserves. Despite their pervasiveness, Lundkvist says that relatively little research has been done on these host rats to date. Reason being: "They are very difficult to trap," he said.

"They are much brighter than other rodents. This is one reason why we know so little at this point."

The infected rats in this study were found by Dutch water management employees in traps they routinely set to capture muskrats at various locations throughout the Netherlands. Sixteen of the rats captured were sent to Lundkvist and his colleagues at the Zoonosis Science Centre, which conducted tests on the rats as part of a rat pathogen collaboration project between the Zoonosis Science Centre and the Symbiant Pathology Expert Centre in the Netherlands. Testing was also conducted at the The Public Health Agency of Sweden in Stockholm and at the Department of Microbiology, Graduate School of Medicine, Hokkaido University in Japan.

Lundkvist, together with a group of researchers comprising a multi-country consortium, is currently writing a grant application for funding that would allow them to look more closely at rats to better understand the risk posed by SEOV as well as other pathogens.

"Rats have been known for years to be carriers of various microorganisms that can transfer to humans," said Lundkvist. "Our study emphasizes the need to further examine the rat population in Europe to better understand the risk they pose to humans."