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Canary Gets Last Laugh: Study Probes Bird Flu in Cats (Update1)
By Jason Gale and Karima Anjani
March 8 (Bloomberg) -- Cats should think twice before they swallow the canary, say researchers studying if felines roaming the streets of Asia may increase the global threat of bird flu.
Domestic and stray cats that prey on birds in Southeast Asia may play a critical role in transforming avian influenza into a global pandemic, virus-tracking scientists say.
To investigate this, researchers next month will begin the world's largest examination of bird flu in stray cats in Indonesia, where a survey found one in five felines carry the lethal H5N1 virus in some areas. Cats, because of their close interactions with humans, may provide a conduit for the transmission of the flu between birds and people.
``Cats eat birds and therefore can become infected by this virus and help it to mutate and adapt'' to mammals, said Andrew Jeremijenko, who headed an influenza surveillance project for the Naval American Medical Research Unit in Indonesia until last March. ``Maybe there is a role that cats are playing and we don't understand it yet.''
Avian-flu experts have long viewed pigs as the mammals in which a pandemic virus may emerge because the farm animals can catch versions of flu that infect birds and humans. As a host for both types of the flu, pigs are one of several species in which the viruses combine and mutate, acquiring properties that make each year's seasonal flu different from the year before.
For the cat study, scientists led by the United Nations' Food and Agriculture Organization will examine feline habits and collect blood samples to test for exposure to the H5N1 virus. Disease trackers aim to collect data during the next three months, with preliminary results collated soon after, said John Weaver, a senior adviser with the agency in Jakarta.
Pandemic Concern
Erasmus University may assist in helping determine how cats become infected, what damage the virus causes to their organs, whether it spreads among the felines and it has undergone any genetic changes, said Ron Fouchier, a virologist at Rotterdam, Netherlands-based Erasmus.
``We have yet to understand the epidemiology of the virus, how it crosses from different species,'' says Weaver. ``If we miss the key component that these cats perhaps disseminate the disease, then we're not catching up with the game.''
The H5N1 virus shares many characteristics with the Spanish flu that killed as many as 50 million people worldwide in 1918 and 1919. Researchers say the virus started in birds, until genetic changes allowed it to spread quickly in people. Cats may be a concern not just because they prey on birds, but because in some parts of the world they share food and beds with people.
Cat Warning
``One thing we do not want is for this virus to become endemic in cats,'' Fouchier said Feb. 27 in a telephone interview. ``As long as these are dead-end infections -- a cat eats a chicken and then dies -- it's not so much of a problem.''
Fresh outbreaks in agricultural poultry and wild birds -- and not actually in canaries -- have been reported in the U.K., Japan and a dozen other countries in the past four months. Laos and Nigeria recorded initial human infections this year, taking the global tally of reported cases to 278 since 2003. Of those, 168 were fatal, the World Health Organization estimates.
Indonesia has the highest death toll with 63 lethal cases. The virus has been found in birds in 30 of the country's 33 provinces. The U.S. embassy in Jakarta last month warned citizens to avoid contact with wild and stray cats, and to ensure that domesticated ones don't interact with sick or dying poultry.
``The prevalence of the virus is quite high'' judging from preliminary tests on swabs of the cats' upper airways, C.A. Nidom, a scientist at Airlangga University in Surabaya, said in a telephone interview on Feb. 28. Nidom found H5N1 in 98 of 500 cats living near poultry markets in high-risk areas on the island of Java and in Lampung province on southern Sumatra island.
Are They Contagious?
Cats are a much-loved animal among Indonesia's roughly 200 million followers of Islam. The religion considers mistreating animals a sin. A story told in the Hadith, a collection of sayings of the prophet Muhammad, says he cut off his sleeve rather than wake a cat that fell asleep on his robes.
Stray cats freely roam the streets of Indonesian cities, congregating around food markets, where they help keep down rodent populations. Only higher-income earners can afford to keep them as household pets because of the cost.
``People throw food to cats at the market so they don't starve to death,'' said Amah, who has sold rice in central Jakarta for more than 40 years. ``There are probably 50 of them living here,'' she said, watching three cats chew on food on the ground next to her stall at the Blora market.
Tigers, Too
Most of the cats infected with the virus don't show any symptoms, according to Tri Satya Putri Naipospos, deputy executive of Indonesia's national committee on avian flu control and pandemic preparedness. It's unclear whether a sick cat can infect a human. Nidom says he plans more research to determine whether felines can pass the illness to other species.
Domestic cats and other felines are at risk of infection from H5N1 if they prey on birds, studies published in March 2006 by researchers at two Thai universities and a government research center showed. A 2005 study showed the virus was probably transmitted between tigers in Thailand. Cat infections were also reported in Germany, Iraq, Russia and Turkey.
``It appears that this is a more significant problem than a one-time event,'' Fouchier of Erasmus said.
China this week said it had found the disease in chickens, geese, crows, hawks, owls, ducks, egrets, cormorants, cranes and gulls in the past year.
At the moment, there is no evidence that cats are of ``any special significance in the maintenance and transmission'' of avian flu, according to Peter Roeder, an animal health officer with the FAO who helped Indonesia set up its bird surveillance.
``There may be some limited transmission but it's a matter of whether that is significant in establishing virus transmission networks,'' Roeder said in a Feb. 28 interview from Rome. ``If we find some cause for concern -- which I doubt that we will -- then we would need to extend the study to other countries.''
To contact the reporters on this story: Jason Gale in Singapore at j.gale@bloomberg.net ; Karima Anjani in Jakarta at kanjani@bloomberg.net
By Jason Gale and Karima Anjani
March 8 (Bloomberg) -- Cats should think twice before they swallow the canary, say researchers studying if felines roaming the streets of Asia may increase the global threat of bird flu.
Domestic and stray cats that prey on birds in Southeast Asia may play a critical role in transforming avian influenza into a global pandemic, virus-tracking scientists say.
To investigate this, researchers next month will begin the world's largest examination of bird flu in stray cats in Indonesia, where a survey found one in five felines carry the lethal H5N1 virus in some areas. Cats, because of their close interactions with humans, may provide a conduit for the transmission of the flu between birds and people.
``Cats eat birds and therefore can become infected by this virus and help it to mutate and adapt'' to mammals, said Andrew Jeremijenko, who headed an influenza surveillance project for the Naval American Medical Research Unit in Indonesia until last March. ``Maybe there is a role that cats are playing and we don't understand it yet.''
Avian-flu experts have long viewed pigs as the mammals in which a pandemic virus may emerge because the farm animals can catch versions of flu that infect birds and humans. As a host for both types of the flu, pigs are one of several species in which the viruses combine and mutate, acquiring properties that make each year's seasonal flu different from the year before.
For the cat study, scientists led by the United Nations' Food and Agriculture Organization will examine feline habits and collect blood samples to test for exposure to the H5N1 virus. Disease trackers aim to collect data during the next three months, with preliminary results collated soon after, said John Weaver, a senior adviser with the agency in Jakarta.
Pandemic Concern
Erasmus University may assist in helping determine how cats become infected, what damage the virus causes to their organs, whether it spreads among the felines and it has undergone any genetic changes, said Ron Fouchier, a virologist at Rotterdam, Netherlands-based Erasmus.
``We have yet to understand the epidemiology of the virus, how it crosses from different species,'' says Weaver. ``If we miss the key component that these cats perhaps disseminate the disease, then we're not catching up with the game.''
The H5N1 virus shares many characteristics with the Spanish flu that killed as many as 50 million people worldwide in 1918 and 1919. Researchers say the virus started in birds, until genetic changes allowed it to spread quickly in people. Cats may be a concern not just because they prey on birds, but because in some parts of the world they share food and beds with people.
Cat Warning
``One thing we do not want is for this virus to become endemic in cats,'' Fouchier said Feb. 27 in a telephone interview. ``As long as these are dead-end infections -- a cat eats a chicken and then dies -- it's not so much of a problem.''
Fresh outbreaks in agricultural poultry and wild birds -- and not actually in canaries -- have been reported in the U.K., Japan and a dozen other countries in the past four months. Laos and Nigeria recorded initial human infections this year, taking the global tally of reported cases to 278 since 2003. Of those, 168 were fatal, the World Health Organization estimates.
Indonesia has the highest death toll with 63 lethal cases. The virus has been found in birds in 30 of the country's 33 provinces. The U.S. embassy in Jakarta last month warned citizens to avoid contact with wild and stray cats, and to ensure that domesticated ones don't interact with sick or dying poultry.
``The prevalence of the virus is quite high'' judging from preliminary tests on swabs of the cats' upper airways, C.A. Nidom, a scientist at Airlangga University in Surabaya, said in a telephone interview on Feb. 28. Nidom found H5N1 in 98 of 500 cats living near poultry markets in high-risk areas on the island of Java and in Lampung province on southern Sumatra island.
Are They Contagious?
Cats are a much-loved animal among Indonesia's roughly 200 million followers of Islam. The religion considers mistreating animals a sin. A story told in the Hadith, a collection of sayings of the prophet Muhammad, says he cut off his sleeve rather than wake a cat that fell asleep on his robes.
Stray cats freely roam the streets of Indonesian cities, congregating around food markets, where they help keep down rodent populations. Only higher-income earners can afford to keep them as household pets because of the cost.
``People throw food to cats at the market so they don't starve to death,'' said Amah, who has sold rice in central Jakarta for more than 40 years. ``There are probably 50 of them living here,'' she said, watching three cats chew on food on the ground next to her stall at the Blora market.
Tigers, Too
Most of the cats infected with the virus don't show any symptoms, according to Tri Satya Putri Naipospos, deputy executive of Indonesia's national committee on avian flu control and pandemic preparedness. It's unclear whether a sick cat can infect a human. Nidom says he plans more research to determine whether felines can pass the illness to other species.
Domestic cats and other felines are at risk of infection from H5N1 if they prey on birds, studies published in March 2006 by researchers at two Thai universities and a government research center showed. A 2005 study showed the virus was probably transmitted between tigers in Thailand. Cat infections were also reported in Germany, Iraq, Russia and Turkey.
``It appears that this is a more significant problem than a one-time event,'' Fouchier of Erasmus said.
China this week said it had found the disease in chickens, geese, crows, hawks, owls, ducks, egrets, cormorants, cranes and gulls in the past year.
At the moment, there is no evidence that cats are of ``any special significance in the maintenance and transmission'' of avian flu, according to Peter Roeder, an animal health officer with the FAO who helped Indonesia set up its bird surveillance.
``There may be some limited transmission but it's a matter of whether that is significant in establishing virus transmission networks,'' Roeder said in a Feb. 28 interview from Rome. ``If we find some cause for concern -- which I doubt that we will -- then we would need to extend the study to other countries.''
To contact the reporters on this story: Jason Gale in Singapore at j.gale@bloomberg.net ; Karima Anjani in Jakarta at kanjani@bloomberg.net
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