April 5, 2006

Cats Must Be Included in Flu Precautions: Experts

By Patricia Reaney

LONDON -- Animal health experts called on Wednesday for new precautions against bird flu because cats, and possibly other mammals, can be infected and could spread the H5N1 virus.

Dr Albert Osterhaus, of Erasmus University in Rotterdam in the Netherlands, also warned that as well as passing H5N1 to other species, cats may help the virus to adapt into a more highly infectious strain in humans which could spark a pandemic.

"We have to take a number of precautionary measures," said Osterhaus, a virologist and veterinarian.

"We need to keep in mind that mammals can be infected and that they can spread the disease, in principle."

Animals such as dogs, foxes, ferrets and seals may also be vulnerable to infection, the researchers said in a commentary in the journal Nature.

They recommended that in areas where avian flu is endemic, cats should not be in contact with birds or their droppings. Cats may need to be kept indoors and if animals or other carnivores show signs of illness they should be tested for H5N1.

"Perhaps there is a case for developing a vaccine for cats as well," Osterhaus told Reuters.


Cats can also act as an early warning signal for the virus.

"When wild birds are infected we have seen that cats are quite effective in catching them and catching the disease. In this way they could be sentinels," Osterhaus said.

Deaths from H5N1, which has infected 191 people and killed 108, have been reported in cats in countries in Asia and in Iraq and Germany. Tigers and leopards in zoos in Thailand have also died after eating fresh chicken carcasses.

"The potential role of cats should be considered in official guidelines for controlling the spread of H5N1 virus," said Osterhaus, Thijs Kuiken of Erasmus University and Peter Roeder, an animal health officer at the Food and Agriculture Organization of the United Nations in Rome, in the journal.

Studies at Erasmus University have shown that cats can be infected through the respiratory tract, in a similar way to humans, but that the more likely route is through the gut by eating infected birds.

The animals develop serious or fatal disease and can transmit the virus to other cats.

"We have shown that cat-to-cat transmission is possible," Osterhaus said. "That is important because it would predispose the virus to adapt to mammals. We cannot exclude that. How big the problem is we don't know."

It has also been shown that the amount of virus excreted by cats through the respiratory tract or in feces is lower than the levels from chickens.

The scientists do not know how long cats can excrete the virus, the minimal amount of virus needed to cause infection in cats or whether virus transmission from cats to poultry, humans and other species is possible.

"But given the potential contribution of these carnivore hosts to both virus transmission and its adaptation to mammals, we believe the time for increased surveillance and precaution is here," they added in the journal.