Thailand Govt Institute
Reports Dogs, Cats With H5N1
FAO Animal Health Special Report
(ProMed - We are grateful to Joe Dudley, who -- in conjunction with posted media reports on avian influenza in dogs Oct 2004 in Thailand and Mar 2006 in Azerbaijan -- has drawn our attention to the above-referenced report. - Mod.AS)
Besides cats, the said review addresses avian influenza in other (non avian) animal species. The following excerpt appears under the title "Information For Veterinarians" -
Carnivores can become infected, after consuming infected poultry that succumbed to the disease. To date no H5N1 clinical cases of dogs have been reported but in an unpublished study carried out in 2005 by the National Institute of Animal Health in Bangkok, researchers tested 629 village dogs and 111 cats in the Suphan Buri district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. [see comment further].
An equine virus has recently shown up in dogs. This inter-species re-assortment is not uncommon for type A influenza viruses.
Pigs are known "mixing vessels" for different influenza virus subtypes and therefore present a risk for avian influenza virus re-[assorting] with a human influenza virus into a strain more apt to infect humans. Regarding the present H5N1 subtype, studies conducted in pigs in Vietnam yielded 8 seropositive animals out of the 3000 pigs tested. None of the animals had any clinical signs and it was not possible to isolate any virus
Ruminants are susceptible to influenza viruses but so far mainly H3N8 have been identified. Regular vaccination is carried out. Experimentally mice can be infected but their role in natural transmission has not been established.
In view of the significance of possible involvement of dogs in H5N1 epidemiology and the lack of scientific references, we have tried to obtain more information on the unpublished study carried out in 2005 by the National Institute of Animal Health in Bangkok. The following commentary has been kindly provided by a colleague in Thailand who spoke with the researchers and had the following comments:
"There are several pieces of information that need to be clarified.
1. The cutoff point in this study is 1:40. The scientists are still debating what the real cutoff point for dogs. They are doing further studies using other methods. Currently they are in doubt about the high percentage of seroreactivity in the dogs.
2. This study was done during the 2nd quarter of 2005 in an area that has a large poultry outbreak.
3. A possible explanation is that the dogs and cats eat sick poultry.
4. While there was a report of a dead cat with H5 in the 1st round outbreak, there is no report in dogs. Most are asymptomatic. In conclusion, it is likely that dogs can be infected by H5 but the [possibility] of spreading the disease to humans is unlikely. However, the role of spreading disease among dogs or to other poultry deserved further study."
We hope that these observations will lead to further studies and conclusions, in Thailand or elsewhere. Field observations remain the most important source of information -- and which ProMED-mail would appreciate receiving. At present, the information on H5N1 in dogs remains anecdotal. - Mods.MPP/AS



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