Thursday, March 16, 2006

Cats, dogs, birds

The Azeris are reporting a stray dog has been found dead of type A influenza in the Azerbaijan village of Rasulzade (Binagadin District) (Regnum). It is being characterized as "bird flu" but dogs are susceptible to other subtypes of influenza than H5N1 and so far we see no laboratory confirmation this is the correct diagnosis. Investigations are continuing.

This would not be the first such report of bird flu in a dog, however. Declan Butler carried a story in Nature last month (13 February issue, subscription only) saying scientists in Thailand suspected large numbers of dogs and cats in that country were infected with H5N1.
In an unpublished study carried out last year by the National Institute of Animal Health in Bangkok, researchers led by virologist Sudarat Damrongwatanapokin tested 629 village dogs and 111 cats in the Suphan Buri district of central Thailand. Out of these, 160 dogs and 8 cats had antibodies to H5N1, indicating that they were infected with the virus or had been infected in the past. "That's a lot," says Albert Osterhaus, a virologist at the Erasmus University in Rotterdam, the Netherlands. "This is definitely something to look into." So far, researchers at Bangkok's Chulalongkorn University have isolated the virus from at least one of the dogs.
Azerbaijan has reported both human and bird infections and recently tallied three deaths in young Azeris. Meanwhile the Indian government is doing a house to house survey in the western Indian Jalgaon district of Maharashtra state where poultry are infected (Reuters). Whether or not the Azeri dog will be shown to be a victim, it is becoming more apparent that this virus is spreading widely amongst a variety of animal species. Several mammalian species, including humans, are already known competent hosts and it is likely the virus is in others as well but no one has looked for it.

With almost daily reports of new localities (Denmark being the latest), we continue to be particularly worried about Indonesia where this virus has been percolating through the animal and human population at least since July and where authorities seem incapable of coping with the situation. They have been seemingly reluctant to ask for the high level scientific help that could shed more light on what is happening there.

Many have noted that the Indonesians have yet to carry out the widespread systematic killing of birds usually advocated. We believe the failure of the Indonesians to ask for the kind of scientific help they so obviously need is reprehensible, but we are willing to cut them some slack on the bird culling issue. First, the evidence that culling is truly effective is not conclusive. Probably more importantly, however, birds play a role as companion animals in Indonesia similar to that of cats and dogs in Europe and the US. Now that both cats and dogs have been implicated as potential H5N1 hosts, one could imagine the reaction to a general culling order for these animals. We are not saying cats and dogs have been shown as important reservoirs of the virus, but only that it is possible to imagine it so as to make a point: a rational strategy to kill all companion cats and dogs in the US or the UK would be infeasible because of cultural resistance.

The spread of bird flu has complex dimensions that elicit complex reactions. If things continue to evolve as they have, we are in for a wild ride.