For several years there has been an ongoing dispute between various factions regarding how H5N1 manages to spread around the world.
Bird enthusiasts and naturalists tend to point to the poorly regulated and controlled poultry trade as being the main source of infection, while those in the poultry industry tend to blame migratory birds.
Since I don’t have a bird in this fight, I readily concede the possibility that both are likely significant factors in the spread of the virus.
Last April, just days before the world’s attention was diverted to a swine origin influenza, I wrote a blog about a study out of India that seemed to rule out migratory birds as a major spreader of the H5N1 virus.
In India: The Role Of Migratory Birds In Spreading Bird Flu I wrote about an article entitled Scientists rule out spreading of bird flu by migrant birds in India from Xinhua News.
At the time, I wrote:
It seems that every few months we get a new report that either implicates – or exonerates – migratory birds as a vector for the H5N1 virus.
Today, we get another study that claims to rule out migratory birds as spreaders of the H5N1 virus in India.
Perhaps it’s so.
At least in the region of the world they investigated.
But there have been studies in other parts of the world that strongly suggest otherwise – that migratory birds do play a role in the spread of avian viruses.
Just a few months before that study, we had this from Hong Kong:
Tuesday, January 06, 2009
A recent bird flu outbreak was likely caused by droppings from migrating wild birds rather than from smuggled ones, experts believe.
A government-appointed committee has completed its initial investigation into the deaths of 200 chickens in a Yuen Long farm early last month, which led to a cull of 100,000 birds and a 21-day ban on the sale of fresh fowl. The report will be submitted to the Food and Health Bureau this week.
According to a source, the report studied several possible factors behind the contamination but concluded there was no evidence linking it to smuggling activities. It was more likely caused by contaminated feces dropped by migrating birds inside the farm or nearby area, the report said.
But if you go back to January of 2008, we get this:
Don't blame wild birds for H5N1 spread – expert
Wed Jan 23, 2008 7:22am EST
BANGKOK, Jan 23 (Reuters) - There is no solid evidence that wild birds are to blame for the apparent spread of the H5N1 virus from Asia to parts of Europe, Africa and the Middle East, an animal disease expert said on Wednesday.
There was also no proof that wild birds were a reservoir for the H5N1 virus, Scott Newman, international wildlife coordinator for avian influenza at the U.N.'s Food and Agriculture Organisation, said at a bird flu conference in Bangkok.
After H5N1 was found in 2005 in a huge lake in central China where it killed over 10,000 wild birds, it turned up in parts of Europe, Africa and the Middle East, leading some experts to believe migratory birds may be to blame.
And so it goes, back and forth.
Today, a fresh report out of China that . . . .you guessed it . . . links migratory birds to outbreaks of H5N1.
While this may not be the last word on the subject . . . it most definitely is the latest.
www.chinaview.cn 2010-01-16 23:19:41
by Xinhua writer Yan Hao
KUNMING, Jan. 16 (Xinhua) -- A research jointly conducted by Chinese and Asian scientists has discovered that highly pathogenic avian influenza (H5N1) outbreak was closely related to bird migration.
The discovery was revealed at the fifth regional meeting of the Asian Partnership on Emerging Infectious Diseases Research (APEIR),which concluded on Saturday in Kunming, capital of southwest Yunnan Province.
Lei Fumin, researcher of Institute of Zoology with Chinese Academy of Sciences, told Xinhua that the research team had studied avian influenza outbreaks along the bird migration routes in the Qinghai-Tibet Plateau.
The research team consisted of Vietnamese, Cambodian, Thai, Indonesian and Chinese scientists.
Studies showed that avian influenza outbreaks in the Qinghai-Tibet Plateau were frequently coincided with bird migration both in time and location.
Studies on migratory birds of different species in different regions which could carry the influenza's virus showed that lakes and wetlands along the migration paths were key zones for the influenza viruses, Lei said.
The studies proved that the role of wild birds in the transmission of avian influenza should be paid great attention to, said Dr. Witthawat Wiriyarat from Thailand, who joined the research team.