Avian Flu - What we need to know

Air purification technology effective against H5N1

Sharp Corporation has demonstrated that Plasmacluster Ions reduce activity of the highly fatal and highly pathogenic airborne H5N1 avian influenza (“bird flu”) virus by 99%. This research was conducted in collaboration with Retroscreen Virology, Ltd., an organization which was established by one of the world’s leading authorities on virology, Professor John S. Oxford of the University of London School of Medicine & Dentistry, and which works in compliance with Good Laboratory Practice*3 (GLP). Among the diverse range of air purification technologies available, Plasmacluster Ions are the first in the world to have been proven effective against this virus.

Here's the full story.

Scary analogies

And now the virus is like a computer, Lambert said, running through reams of data trying to break a code until it hits on the right sequence — “the combination that will allow it to spread person to person.”

Read more here.

Indonesia: bird flu found in pigs

Bird flu has infected pigs in Indonesia, raising fears of a wider outbreak in the world's fourth-most populous country and South-East Asia's biggest economy, the Agriculture Ministry said today.

The ministry conducted tests after scientists reported that pigs in several farms on the main island of Java were infected.

"We will continue to take some measures to prevent the avian influenza virus from spreading," Agriculture Minister Anton Apriyantono said.

"As soon as we have enough details, we will explain it further."

So far there have been no reports of people in Indonesia being infected with the H5N1 bird flu virus.

The full story comes from the Daily Telegraph. Here is an earlier post of mine on the link between agricultural practices and bird flu transmission to pigs.

Bureaucracy as a major problem in fighting the flu

The best shot to stop a developing pandemic is to isolate and treat it fast:

Klaus Stöhr, who coordinates the influenza programme of the World Health Organization (WHO), says there is only one option for extinguishing an emerging human pandemic: rapid identification of cases, and treatment of patients and all their contacts with the antiviral drug Tamiflu (oseltamivir phosphate). Modelling studies suggest this should work if action is taken quickly enough¹.

This may be very hard to do in some countries:

The models predict that there will be only a short window of opportunity in which to act: up to 30 days after a new case is detected. But the Vietnamese health ministry often takes two to four weeks to declare cases, according to the WHO.

"This leaves just a few days to intervene, making it very unlikely that we could stop a virus," says Stöhr. "Without fast reporting and detection of cases, the world is gambling away the small (and unproven) chance we have of stopping an emerging pandemic in its tracks."

Stöhr says the WHO has offered assistance to Vietnam, but this hasn't been accepted fully. "The affected countries lack trust in the international agencies, including the WHO," says Robert Webster, director of the US Collaborating Center of the WHO that deals with the ecology of animal flu viruses. "There is a reluctance in these countries to give the agencies access."

The story comes from this nature.com article. Here's an earlier post by Tyler Cowen on the feasibility of cooping up bird flu.

CDC: possible horizontal H5N1 transmission in tigers

According to a CDC report from May 2005, tiger-to-tiger transmission likely occurred in Thailand in October 2004, during an H5N1 outbreak at a zoo:

During the second outbreak of avian influenza H5N1 in Thailand, probable horizontal transmission among tigers was demonstrated in the tiger zoo. Sequencing and phylogenetic analysis of those viruses showed no differences from the first isolate obtained in January 2004. This finding has implications for influenza virus epidemiology and pathogenicity in mammals.

Our results demonstrated that tigers kept in captivity are at risk for infection with and dying of the H5N1 virus; moreover, they could be infected by horizontal transmission since raw chicken carcasses represent the main food item for them. Alternative food for the tigers should be considered to reduce the risk for infection. Epidemiologic data obtained from this study demonstrated that all tigers that became ill after October 23, 2004, were probably infected by horizontal transmission since the animals had not been fed raw chicken carcasses since October 16.

The outbreak took place at the largest tiger zoo in Thailand, where a total of 441 tigers lived.

Australia remains H5N1 free as migratory birds flock north

Australia, one of the few countries of the Asia-Pacific region that has not been hit by the deadly H5N1 strain of bird flu, has survived the most dangerous time of year for the spread of the infection.

The end-of-summer departure of millions of migratory birds had greatly reduced the risk of them introducing the deadly virus from Asia, spreading it to native birds and eventually into the human food chain, government officials said on Wednesday.

Australia has had five previous outbreaks of bird flu, most recently in 1997, with the infection brought in by migratory birds that defecate into water, passing the flu onto wild birds.

Australia's chicken industry had taken stringent measures, treating water and erecting elaborate screens against wild birds.

Full story from Reuters.

Can we coop up avian flu?

The May 2005 Scientific American has a notable article about delaying the spread of avian flu:

...detect the first clusters quickly and then slow or squelch the emerging virus by blanketing the outbreak area with antivirals.  In the past, "no one even considered this thought of containment on the agenda," says Emory University biostatician Ira M. Longini, Jr...Longini is one of several researchers using computer models to test the strategy...

A given case of flu typically does not spread to many people, but flu moves quickly because it has a brief incubation period before it starts infecting others.  Longini argues that an infected area should be blanketed with tamiflu and perhaps "draconian quarantine" should be applied as well. 

According to some of his simulations, heavy prevaccination, following news of an outbreak, can shut down an epidemic if a given case of virus infects 1.4 people or fewer (the "R" variable).  Longini argues that avian flu, in its early stages, probably would have an "R" no greater than one.  The 1918 pandemic had an R of about 2, it is estimated.

No on-line story yet, but here is Longini's home page.

How does avian flu get transmitted to pigs?

Here is one account from Promedmail, an excellent site maintained by the International Society for Infectious Diseases:

This is from one of my colleagues (a doctor) who is working in Indonesia. He visited a pig and chicken farm in Bali.

"There were 1000 chickens living over 20 pig pens with just slats between them.  It is a farming system called tampung sari. This way the chickens' faeces falls directly to the pigs and they eat it. Apparently pigs can get up to 40 percent of the RDA [nutritional recommended daily allowance ] from chicken faeces, and it is common practice to feed chicken faeces to pigs.

To my knowledge culled chickens are not used to feed pigs (at least in tampung sari), but it is possible. It is well known that chicken faeces [i.e., feces from infected chickens] contain H5N1, so the exposure from chicken faeces is enough to explain the finding.

Likewise, in China, ducks and pigs live closely together so that it is easy to explain the finding of H5N1 in pigs in China in 2004."

[Integrated farming systems are meant to utilize the products of one sub-system by another sub-system, generating useful materials like protein biomass in the process. Various combinations are known. In Southeast Asia, integrated systems combining chickens/ducks, pigs and fish are widely applied. - Mod.AS]

For further reading, here is a paper on integrated fish-livestock systems, and an older article on the possible link between agricultural practices and transmission/mutation in viruses.

Avian flu identified in Indonesian pigs

From today's NewScientist.com:

Indonesian scientists have found the H5N1 bird flu virus in a pig. The strain has infected poultry across east Asia, and killed at least 51 people so far.

Pigs are of concern because they can be infected by both bird flu viruses and flu viruses from mammals. A hybrid bird-human virus could have a haemagglutinin from birds that human immune systems will not recognise, and genes from human-adapted flu that will make the hybrid highly contagious in people.

“It is almost certainly true that viruses of different species can mix in pigs - pigs have numerous “hybrid” viruses,” says Richard Webby of St Jude’s Children’s Research Hospital in Memphis, US. “But the pig as a mixing vessel for human flu pandemics is just a hypothesis.”

The pandemics of 1957 and 1968, which killed millions, did seem to result from the mixing of bird flu strains with mammalian flu, although where this occurred is not known. However, the even greater 1918 pandemic did not.

There is some good news:

Robert Webster of St. Jude’s told a meeting on biosecurity in Lyon, France in March that his lab has found that H5N1 grows well in pigs, making hybridisation theoretically possible. But it might not get far - infected pigs, Webster told New Scientist, do not pass H5N1 to each other. This means relatively few pigs will catch it.

Full story.

Does cockfighting spread avian flu?

From today’s Washington Post:

Cockfighting, popular in many parts of Southeast Asia, is suspected of spreading the highly lethal bird flu virus from poultry to humans through contact with blood, feces and droplets of fluid. It is one of several cultural practices, including the eating of raw duck blood and the raising of chickens in back yards, that are threatening to help spark a global pandemic that the World Health Organization warns could kill tens of millions of people.

For centuries, these practices posed no human threat. But a dramatic increase in poultry farming in the region in the past 15 years has allowed avian influenza to become entrenched in the bird population. Now, these cultural routines represent a potential springboard for a human epidemic.

"There will be opportunities for the virus to take advantage of these practices," said Klaus Stohr, director of WHO's global influenza program. "They didn't cause trouble before, but now they do."

In September, the virus killed an 18-year-old Thai man who raised fighting cocks outside Bangkok. Thai health officials said he had the habit of sucking mucus and blood from the beaks of his injured roosters and sometimes even slept with his birds. Earlier last year, a 13-year-old boy who frequented cockfights in Vietnam's Ho Chi Minh City and often held the birds before the bouts also succumbed to the disease.

Read the full article.