# 2982
The H5N1 virus may be commonly called `bird flu’, but it has shown an ability to infect a surprisingly wide range of hosts.
Many species of birds are susceptible, of course. But we've also seen infections in a wide variety of mammals; including cats, dogs, martens, civets, and of course humans.
Researchers have successfully infected cattle with the H5N1 virus, along with ferrets and mice for testing.
Last November I wrote about a seroprevalence study done on wild raccoons in the United States that showed they can carry antibodies to a wide variety of human and avian influenzas (see Reservoir Dogs (Cats, Foxes, and Raccoons)
Hall JS, Bentler KT, Landolt G, Elmore SA, Minnis RB, Campbell TA, et al. Influenza infection in wild raccoons. Emerg Infect Dis. 2008 Dec; [Epub ahead of print]
The study looked specifically for influenza antibodies in wild raccoons and they also experimentally infected raccoons with the H5N1 virus.
Here is the abstract, slightly reformatted for easier reading.
ABSTRACT
Raccoons (Procyon lotor) are common, widely distributed animals that frequently come into contact with wild waterfowl, agricultural operations, and humans.
Serosurveys showed that raccoons are exposed to avian influenza virus. We found antibodies to a variety of influenza virus subtypes (H10N7, H4N6, H4N2, H3, and H1) with wide geographic variation in seroprevalence.
Experimental infection studies showed that raccoons become infected with avian and human influenza A viruses, shed and transmit virus to virus-free animals, and seroconvert.
Analyses of cellular receptors showed that raccoons have avian and human type receptors with a similar distribution as found in human respiratory tracts. The potential exists for co-infection of multiple subtypes of influenza virus with genetic reassortment and creation of novel strains of influenza virus.
Experimental and field data indicate that raccoons may play an important role in influenza disease ecology and pose risks to agriculture and human health.
While the research in the United States didn’t turn up any H5N1 antibodies (no surprise, since we haven’t see it in birds yet), a small number of human and avian influenza virus antibodies were detected.
In laboratory experiments, scientists were able to infect raccoons with the H5N1 virus. They, in turn, shed the virus and could pass on the infection to other raccoons.
So, I suppose we shouldn’t be terribly surprised by this news report today in the Yomiuri Shimbun, saying that Japanese scientists have found 10 raccoons with H5N1 antibodies in that country.
Japan has, on rare occasions, detected the H5N1 virus in wild birds, but it has never before found the virus in mammals.
The presence of antibodies indicates a previous exposure to the virus, not an active infection.
10 raccoons discovered with bird flu antibodies
The Yomiuri Shimbun
UTSUNOMIYA--Ten wild raccoons have been found with signs of previous H5N1 bird flu infections, according to a joint study by Tokyo University and Yamaguchi University.
This is the first time mammals in this country have been found with bird flu virus antibodies, which develop as a result of infection. Before the discovery, only birds had been found with bird flu antibodies.
The research team, which presented a paper on its findings at a conference of the Japanese Society of Veterinary Science in Utsunomiya on Saturday, warned that infected raccoons could introduce the virus into chicken farms and noted that countermeasures were needed.
It is believed that the H5N1 strain of the bird flu virus is highly likely to mutate into a new type of influenza. In Japan, there have previously been reports of domestic chickens, wild whooper swans, jungle crows and mountain hawk-eagles infected with the virus.
The research team collected and examined blood from 988 raccoons captured since 2005 at three locations in western Japan and one location in eastern Japan. In the blood of 10 raccoons from three of the locations, the team found antibodies that had developed after past H5N1 infections. In two of the three places, not even birds had been found with the antibodies before this time.
According to Taisuke Horimoto, an associate professor of Tokyo University's Institute of Medical Science, raccoons do not live in packs. He said the blood test this time showed that in comparison with other infectious diseases, the proportion of animals found with the H5N1 antibodies was low.
The researchers think the 10 raccoons likely were not infected by other raccoons, but by eating the carcasses of infected birds or inheriting the antibodies from a parent at birth.
Raccoons are found throughout the nation. Many of them are descended abandoned pets or have run away from zoos.
The ability of small mammals to contract and potentially serve as a reservoir for the virus may help answer (at least in part) why the virus seems to be reintroduced into some areas within a few weeks or months after extensive culling has taken place.
