- Cats are significantly more likely to
catch and pass on bird flu than has generally been thought and could help
the virus to mutate to cause a human pandemic, scientists said today.
- The pets' role in the spread of the H5N1
virus, and the potential risk they pose to their owners, have been underestimated
by public and animal health bodies, according to a team of leading virologists
from the Netherlands.
- Research at the Erasmus Medical Centre
in Rotterdam has shown that the cats catch bird flu reasonably easily,
either by close contact with infected birds or by eating them, and that
they can transmit the virus to other cats.
- This could give the H5N1 virus new opportunities
to adapt to mammals, including humans, making the emergence of a pandemic
strain that spreads easily from person to person more likely, the scientists
said in the journal Nature.
- Albert Osterhaus, who led the work, said
that the findings make it important for cats to be confined indoors in
areas where the disease is endemic, to limit their contact with infected
wild birds or poultry.
- Affected regions of Germany and France
have already ordered that cats be kept indoors, but the Department of the
Environment, Food and Rural Affairs (Defra) has not yet said whether it
would make similar provisions should bird flu reach Britain. [An H5N1-infected
swan is said to have been initially traced in Fife, Scotland, on Tue, 28
Mar 2006. - Mod.AS]
- Dr Osterhaus said that while none of
the 191 human cases of bird flu has been contracted from a cat, it is impossible
to rule out such transmission. Though infected cats shed much less of the
virus than do birds, the very close contact that many owners have with
their pets could potentially put them at risk.
- "The point we are trying to make
is that as soon as the virus becomes endemic in wild birds or poultry,
it would be wise to realise that cats are susceptible animals," he
said. "As soon as you have birds that become sick, cats are very effective
at catching and eating them. Our advice is that in endemic areas you should
keep cats indoors and dogs on the lead [leash].
- There is also a public health concern.
Although the risk is not large because the level of virus excretion is
lower than birds, there is a concern because people tend to take good care
of sick pets. It is unlikely that people will get too close to a chicken,
but many people do with cats. You would not want an infected cat in a household
situation. There is still no need to panic, but if you're in an endemic
area you should keep your cats indoors."
- The first cases of H5N1 among cats were
reported in Thailand in 2004, when 14 out of 15 cats in a household near
Bangkok became ill and died after eating an infected chicken carcass. Infections
were then identified among leopards and tigers fed on poultry at Thai zoos.
In Europe, cases have recently been confirmed among domestic cats in Germany
- Dr Osterhaus said it was also clear that
infection is prevalent among domestic cats in countries where bird flu
is endemic such as in Thailand, Iraq and Indonesia.
- In the last of these, the feline version
of the disease has its own name: "It is sufficiently well known to
have been given an onomatopoeic name in the local Javanese dialect -- "aargh-plop'"
- Experiments in Rotterdam have shown that
cats can be infected via the respiratory tract, by eating infected meat,
or by contact with other infected cats. While the overall risk to humans
is difficult to assess, it is impossible to rule out, Dr Osterhaus said.
- "Apart from the role that cats may
play in H5N1 virus transmission to other species, they also may be involved
in helping the virus to adapt to efficient human-to-human transmission,"
- "Cats may provide the virus with
an opportunity to adapt to efficient transmission within and among mammalian
species, including humans, thereby increasing the risk of a human influenza
- "We believe that the potential role
of cats should be considered in official guidelines for controlling the
spread of H5N1 virus infection. Most international guidelines currently
lack such considerations."
- "The possible role of cats in the
epidemiology of H5N1 virus infection has been largely overlooked by the
human- and animal-health communities."