First hantavirus transmission by a house rat


Rat as a pet. (Image: Sergei Pivovarov / iStock)

For the first time in Germany, the transmission of the Seoul virus to humans was detected. A young woman from Lower Saxony was infected by her pet rat. With acute kidney failure, she had to be treated in intensive care. The Seoul virus belongs to the hantavirus family and is mainly found in Asia. So far, only hantavirus types have occurred in Germany that are transmitted by mice and usually cause milder courses.

Hantaviruses are spread all over the world. Their hosts are small mammals such as mice and rats, through whose excretions the viruses can be transmitted to humans. So it is a question of zoonoses. Depending on the virus species, they produce courses of varying severity – from asymptomatic courses to life-threatening hemorrhagic fever with kidney failure. Hantavirus diseases have been notifiable in Germany since 2001. In Central Europe, the Puumala and Dobrava-Belgrade viruses, types of hantavirus which are transmitted by mice and only rarely lead to severe disease, are found in Central Europe.

Identical virus sequences in rat and owner

In an 18-year-old rat owner from Lower Saxony, an infection with the Seoul virus, which is new in this country, has now been detected. This pathogen causes a clinical picture similar to that of the already known hantaviruses, but more often leads to severe courses. As scientists from Charité – Universitätsmedizin Berlin and the Friedrich Loeffler Institute (FLI) have now announced, the patient was admitted to hospital in October 2019 with a high fever and poor general condition. In the course of her illness, she developed acute kidney failure as well as liver and gastrointestinal problems. It took about two weeks for her to be released from the hospital.

First serological analyzes quickly confirmed that it was a hantavirus infection, but the type was initially unclear. It was not until a team led by Jörg Hofmann from Charité carried out advanced molecular diagnostics that identified the pathogen as the Seoul virus. Experts at the Friedrich Loeffler Institute were able to detect the same virus in the affected home rat. Hofmann explains: “Both virus sequences, that of the patient and that of the rat, were identical. This confirms a disease through the transmission of the pathogen from animals to humans – a so-called zoonosis. “

So far hardly any cases in Europe

This was the first time that the Seoul virus was transmitted in Germany. So far, only individual cases from France and the Netherlands have been known. “This virus originally came from Asia and probably got to Europe through infected wild rats on ships, but has never been observed in Germany,” says Hofmann. The only case in Germany so far was a pensioner who contracted the virus in 2017 while on a trip to Indonesia.

The patient’s infected breeding rat was allegedly imported into Germany from another country. The young woman bought the animal two to three weeks before her illness broke out. Follow-up examinations should show the exact origin of the pet rat and the pathogen found there. For this purpose, further studies of rat husbandry and wild rats are planned. A few years ago there were cases of cowpox virus transmitted by home rats. “The detection of another zoonotic pathogen in domestic rats underlines once again the necessity of monitoring domestic rats for zoonotic pathogens,” says co-author Rainer Ulrich from the National Reference Laboratory for Hantaviruses at the FLI.

Rats as vectors

As far as is known so far, the hantaviruses found in Europe and Asia are only transmitted from animals to humans, but not from person to person. Their distribution is therefore linked to the habitats of the corresponding host animals. “Until now, people only thought of hantavirus infections when they came into contact with mice. Now you have to consider the possibility of an infection in contact with wild or domestic rats, ”warn the authors. “The evidence in a pet rat also means that the virus can be exported practically anywhere through the sale of these animals.” Further investigations should clarify the extent to which this poses a risk for rat keepers, rat breeders and the general population.

Source: Jörg Hofmann (Charité – Universitätsmedizin Berlin) et al., Emerging Infectious Diseases, doi: 10.3201 / eid2612.200708

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