Here is some good stuff. Note that research on H5N1 began in 1961, with cats.
H5 infects humans and has healthy reservoir in water Aves spp.. Both low- and high-pathogenic strains exist, depending at least partly on the amino acid sequence at the cleavage site in HA1/HA2. Detection of an H5 subtype of influenza A in a human should always arouse a very high level of suspicion that the case was caused by the H5N1 strain of avian influenza, particularly in a country with ongoing outbreaks of H5N1 in poultry. H5N1 is the only strain within the H5 subtype that has ever been shown to cause disease in humans. The next influenza pandemic: lessons from Hong Kongref.
Epidemiology :
The Netherlands : on Mon Mar 15, antibodies against H5 LPAI were detected also in ducks at a farm in Lopik in the central province of Utrecht : although the virus could not be isolated, the government decided not to take any risk and thus ordered the culling of all 800 ducks. On Mar 19 some 1000 birds (442 ducks, 531 chickens, 5 turkeys, 9 geese, and 77 doves) were culled at a farm in Steenbergen (in the southern province of North Brabant), which had links to a farm in Lopik. The source may have been 2 shipments of a total of 2500 ducks from France : 5 other farms, which also received ducks from the 2 shipments, are still under investigation. On Mar 20 99 birds (34 ducks, 35 chickens, 3 turkeys, 3 geese, and 24 doves) were culled in a farm located at Liempde, province of North-Brabant
Canada : on 18 Nov 2005 a duck on a farm in Abbotsford in the Fraser Valley east of Vancouver, south western British Columbia tested positive by RT-PCR. On Jun 2006 4 domestic goose (purchased about 6 weeks before from a local co-operative) died in western Prince Edward Island and one tested positive for an H5 avian influenza virusref
Subtypes :
H5N1 subtype
First isolated from Sterna hirundo (common terns) in South Africa in 1961ref. it was probably transmitted by Odontophoridae infected with H9N2, Anser spp. infected with H5N1, and Anas spp. infected with H6N1 from Continental China to Gallus gallus in Hong Kong markets, and then to humans. Researchers introduced the H5N1 virus into the airways of 3 cats and 3 other cats were fed an infected chick. Finally, 2 cats were exposed to the virus by being placed in the same cage as the 1st 3 cats. The cats soon showed signs of disease: raised body temperature, decreased activity, and labored breathing. All developed severe lung disease. One cat died after 6 days of infection. The study authors also tested the effect of another type of influenza virus, H3N2, which most commonly causes flu in humans. Cats exposed in the same way to this virus did not develop disease. During H5N1 virus outbreaks, domestic cats are at risk of disease or death from H5N1 virus infection, either due to feeding on infected poultry or wild birds, or due to contact with infected cats. The role of cats in the spread of H5N1 virus between poultry farms, and from poultry to humans, needs to be re-assessed. Cats may form an opportunity for this avian virus to adapt to mammals, thereby increasing the risk of a human influenza pandemicref. Anyway it could not be passed between humans. Due to Asp92=>Glu in NS1, virus is resistant to IFNs and TNF-a.
Epidemiology (see also under veterinary medicine : avian influenza). One of the 2 strains, or clades, of HA that emerged since 2003 made people sick in Vietnam, Cambodia and Thailand in 2003 and 2004, while the other caused the disease in people in Indonesia in 2005. Recent avian and human isolates are predominantly genotype Z viruses but additional avian isolates of genotype V and Z/W reassortants are also circulating. The hemagglutinin (HA) gene has evolved considerably since 2003 into distinct clades (1, 1’ and 2). Human and avian isolates from
Vietnam, Thailand, Cambodia, Malaysia and Laos are genotype Z and have a clade 1 HA. Viruses with clade 2 HA belong to genotypes Z, V or Z/W reassortants and are responsible for the recent outbreaks of avian influenza in Indonesia, China, Japan, South Korea, Vietnam and Eastern Europe andhuman cases in Indonesia. Clade 2 HA can be further subdivided into at least 6 subclades (2A-F) with distinct amino acid motifs and the potentialfor different antigenic profiles. Positive selection analysis of all H5N1 HA showed that amino acids corresponding to two major antigenic sites are under selective pressure (Garten, R. Analysis of H5N1 Influenza Viruses from Humans and Birds Between 2003 and 2005 Reveals an Increase in the Spectrum of Viruses with Pandemic Potential. ICEID2006 Abstractref)
http://focosi.immunesig.org/pathoviruses_influenzaA.html#H5
Hmmm... Interesting post.
Research on H5N1 began in 1961. On cats.
There were a number of reports last year of H5N1 in various mammals, mostly predators. It was thought they had probably eaten infected birds.
The genetic sequences recently found in humans are not matching up with those found in birds. This is leading to speculation that H5N1 has an animal reservoir (host?) other than birds. (Cats??)
Interesting.