Cats Spread Bird Flu

The specter of massive bird flu epidemics turns more and more present, as cats have been recently identified as a vector for the H5N1 virus.

If the virus mutates inside the cats, it could easily spark a huge epidemics.

In the first research of its kind, 20 % of the cats in areas where outbreaks of H5N1 in poultry and humans were signaled in Indonesia presented antibodies against the virus, which means they had been infected, most likely through consuming the meat of infected birds, and survived.

In this case, the virus gets increased opportunities across Asia and Africa to adapt to mammals, and consequently to people.

The research sampled 500 stray cats in 4 areas in Java and one in Sumatra.

Even if only 20 % were tested positive for antibodies, many other infected cats must have died, as many dead cats were reported from H5N1 outbreaks, thus more than 20 % of the cats got infected.

That's much more than in the populations of apparently healthy birds in Asia.

Thus, like in humans, some cats die, others survive.

But unlike humans, they seem to carry large amounts of virus, and infect amongst themselves.

"I am quite taken aback by the results," said Chairul Anwar Nidom of Airlangga University in Surabaya, Indonesia, who also found the virus in Indonesian pigs in 2005.

The infection has also been detected in dogs and cats on the Bali Island which experienced outbreaks of H5N1.

The virus was first time found in cats in 2004.

By the moment, cats cannot infect people, who take it even from birds with some difficulty.

"The main worry is that as the virus replicates in cats it will further adapt to mammals and acquire the ability to spread more efficiently to people and from person to person, unleashing a human pandemic," said Albert Osterhaus of Erasmus University in Rotterdam, the Netherlands.

Cats dead by H5N1 were also signaled in Thailand, Iraq and Germany and infected but surviving in Austria; but in Thai Zoos, there were found cases of tigers and leopards dead by H5N1.

Cats present a higher percentage of infection than birds, because predators eat many prey animals and this increases the infection chance.

"At least that percentage shows the virus has not completely adapted to cats - yet," Osterhaus says.

"We know the 1918 pandemic was a bird flu virus that adapted to mammals in some intermediate mammalian host, possibly pigs," said Osterhaus.

"Maybe for H5N1 the intermediate host is cats."

If till now 267 humans have died by avian flu, the dead cats must have been for thousands.

Every sick cat gives the virus a chance to adapt, and there are plenty of opportunities this year in China, Indonesia, Japan, South Korea, Hong Kong, Vietnam, Thailand, Egypt and Nigeria.

"Killing cats won't solve the problem and would lead to a population explosion of disease-carrying rodents" said Osterhaus.

"Cats must just be kept from eating sick chickens," added Osterhaus.

This is a difficult task in open-air markets across Asia and Africa, which are typically swarming with hungry stray cats.

In Indonesia, slaughtered chickens are handed back for their owners to eat, and it's hard to imagine cats won't receive their share.