# 1620
Ever since bird flu reemerged in 2004, most officials have assured us that the only way to contract the H5N1 bird flu virus was through direct, close contact with infected fowl.
Roughly 18 months ago, that story began to waver a bit, with the Karo cluster in Indonesia strongly suggesting limited H2H (Human to Human) transmission. Since then, other suspicious `clusters' have been detected, with limited H2H transmission apparently occurring in Pakistan and China late last year.
Additionally, we've learned that the host range of the virus, the number species it can infect, is larger than we imagined. Dogs, cats, tigers, pigs, and ferrets, along with humans and birds are susceptible. There may well be others. Even flies have been mentioned as possible vectors.
This opens the door to other possible reservoirs beyond avian species for the virus.
Recently the WHO admitted that 25% of all human H5N1 infections were of uncertain origin.
Exposure source unclear in 25% of human H5N1 cases
Jan 16, 2008 (CIDRAP News) – In at least 25% of human infections with the H5N1 avian influenza virus, just how the person was exposed to the virus remains a mystery, according to a report by an expert panel set up by the World Health Organization (WHO).
While human infections have been reported in 14 countries, Indonesia holds the dubious record of suffering the most casualties. Scientists there are seeing a change, they say, in the way the virus behaves.
Less often do they find a link to infected birds, and that has everybody concerned.
So far, the virus remains difficult for humans to catch.
This from AFP.
'Mysterious' bird flu baffles Indonesian scientists
Wed Feb 6, 1:37 AM ET
JAKARTA (AFP) - Indonesian scientists and officials said they were baffled by the "mysterious" behaviour of the bird flu virus here, which has already claimed nine lives this year in the world's worst-hit nation.
Indonesia has reported 126 cases of H5N1 bird flu, 103 of them fatal, since 2005. This year's victims have all come from the capital Jakarta and its satellite cities.
Officials from the ministry of agriculture's bird flu control unit told a media briefing that the risk factors for human infection remained unclear after studies were conducted around victims' homes.
"In some of the cases we found the virus in the water and chickens, but in many other cases the studies showed no signs of the virus in the surroundings," said the unit's Tjahjani Widjastuti at the briefing late Tuesday.
The usual mode of transmission of the deadly H5N1 strain of bird flu is directly from an infected bird -- typically poultry -- to humans.
"The behaviour (of the virus in Indonesia) is mysterious and we are competing with the dynamics of the virus. There needs to be deeper study on why there are more cases in humans, what are the risk factors... so we can cut the chain of infection to humans," Widjastuti said.
< snip>
Meanwhile, early partial results of a study conducted by the UN's Food and Agriculture Organisation bird flu programme in Indonesia in traditional markets in western Java -- which covers Jakarta and its surrounds -- showed a high level of penetration by the virus.
About half of all markets tested were positive for the virus, said James McGrane, leader of the FAO programme.
