From the CIPRAP website:
http://www.cidrap.umn.edu/cidrap/content/influenza/avianflu/news/oct1105flureview.html
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Experts cite differences between H5N1 and ordinary flu
Oct 11, 2005 (CIDRAP News) – A recent and extensive review of research on H5N1 avian influenza in humans shows the illness differs from ordinary flu in several ways, besides the most obvious fact that it is far more deadly.
The report by a World Health Organization (WHO) committee says avian flu may have a longer incubation period and is more likely to cause diarrhea than typical flu viruses are, among other differences.
Published in the Sep 29 New England Journal of Medicine, the review was written by experts from several countries, including Vietnam, Cambodia, Thailand, the United States, the United Kingdom, Hong Kong, and Myanmar. They reviewed 71 published studies and reports, including details on 41 confirmed human cases from Vietnam, Thailand, Cambodia, and Hong Kong.
The H5N1 virus first jumped from birds to humans in Hong Kong in 1997, infecting 18 people and causing 6 deaths. In late 2003 the virus began sweeping through poultry flocks in East Asia, and since then it has struck at least 116 people and killed at least 60, by the WHO's official count.
The new report says the virus may incubate longer than other human flu viruses before causing symptoms. Incubation periods in ordinary flu range from 1 to 4 days, with an average of 2 days, according to the Centers for Disease Control and Prevention (CDC). In H5N1 cases, the incubation time has mostly been from 2 to 4 days but has stretched to 8 days, the WHO report says. In household clusters of cases, the time between cases has generally ranged from 2 to 5 days but sometimes has been as long as 17 days.
Initial symptoms are more likely to include diarrhea in avian flu than in ordinary flu, the report says. The problem can appear up to a week before any respiratory symptoms. That feature, combined with the detection of viral RNA in stool samples, suggests that the virus grows in the gastrointestinal tract.
Lower respiratory tract symptoms such as shortness of breath appear early in the course of the illness, whereas upper respiratory symptoms such as runny nose are less common, the article says. Also, unlike in ordinary flu cases, the virus may be found in larger amounts in the throat than in the nose.
Most cases so far have been linked with exposure to poultry. Specific activities that have been implicated include plucking and preparation of diseased birds; handling fighting cocks; playing with poultry, especially asymptomatic infected ducks; and consumption of duck's blood or possibly undercooked poultry, the report says.
Blood tests of people in contact with H5N1 patients in Vietnam and Thailand have shown no evidence of asymptomatic infections. However, surveillance involving polymerase chain reaction (PCR) tests has revealed mild cases, more infections in older adults, and an increase in family clusters of cases in northern Vietnam—"findings suggesting that the local virus strains may be adapting to humans," the article says. (The WHO first reported these findings in May; see link to more information below.)
But it adds that more work is needed to confirm these findings, and so far the disease has rarely spread to healthcare workers, even when appropriate isolation measures were not used.
The article says the relatively low number of human cases amid widespread infection in birds suggests that the species barrier to human cases of H5N1 is "substantial." The authors add that family clusters of cases may be caused by common exposures rather than by person-to-person transmission.
The report also discusses the "severe" lung injury found in autopsies of H5N1 victims, whose lungs become choked with debris resulting from the body's intense response to the infection. The authors say the body's innate immune response to the virus, involving heavy release of proteins that trigger inflammation, may contribute to the severity of the disease.
Most patients hospitalized for H5N1 infection have received antiviral drugs, usually oseltamivir, the report says. This treatment appears to be helpful only when started early in the illness.
Recent experiments on mice suggest that the virus has become less susceptible to oseltamivir since 1997, the article notes. To reap a similar benefit, mice infected with a 2004 strain of the virus needed a higher dosage and longer course of oseltamivir than mice infected with a 1997 strain did. Hence, the report suggests that physicians treating severe infections should consider doubling the approved dose.
Oseltamivir is one of the two neuraminidase inhibitors used for flu. The other one, zanamivir, has not been studied in H5N1 cases, the report says. The two older antivirals used for flu, amantadine and rimantadine, no longer work against H5N1.
Writing committee of the World Health Organization (WHO) Consultation on Human Influenza A/H5. Avian influenza A (H%N1) infection in humans. N Engl J Med 2005 Sep 29;353(13):1374-85 [Abstract]
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WHO is now stating that amantadine no longer works against H5N1. I may be wrong when I state that it works against some strains of H5N1. It was my understanding that the Chinese were the ones who regularly used amantadine to prophylactically treat chickens on an industry-wide basis, that in other areas amantadine was NOT used (Indonesia, VietNam) and that strains of H5N1 developing in areas other than China were still sensitive.
I don't know the answer on this. If anyone does, please advise this thread.
Thank you.
> WHO is now stating that amantadine no longer works
> against H5N1. ... It was my understanding that the
> Chinese were the ones who regularly used amantadine
> to prophylactically treat chickens on an industry-wide
> basis, ...
Does the latter explain the former? Seems like an
effective way to "encourage" the virus to develop
a resistance to that agent.
Resentment grows in bird flu town
By Sarah Rainsford
BBC News, Kiziksa, western Turkey
As a precaution all bird stocks are being culled in Kiziksa
"Bring your poultry to the town square this evening for slaughter," a voice orders, wafting from loud speakers on Kiziksa town hall.
"Failure to comply could mean up to six months in jail."
The threat is the final stage of a cull in the remote rural town that is now famous here - home to Turkey's first ever outbreak of avian flu.
More than 5,000 birds have been killed so far - in this, the country's prime region for poultry.
Financial ruin
Mehmet Eksen says he knew something unusual was afoot when 50 of his turkeys fell sick and died last Monday. Another 100 died the next day.
Now my whole world has been turned upside down. I'm finished
Mehmet Eksen
Send us your comments
"I thought they'd been poisoned so I treated them with ayran (yoghurt drink) at first," Mehmet explains.
But they showed no response, so he reported the deaths on Wednesday - and vets have since slaughtered his entire stock.
"I sold my flat and invested my family's future in my business," Mehmet says. "Now my whole world has been turned upside down. I'm finished."
Samples taken from Mehmet's turkeys have confirmed the presence of the H5 flu virus. Specialists in Britain are now working to determine if this is H5N1 - the strain known to be fatal in humans.
Migration problem
Scientists here suspect Mehmet's turkeys were infected by birds flying south from Russia. They used to range freely on land close to Bird Paradise National Park - a popular stopping-off spot on the migration route.
The only other farmer who used that land is Sitki Boskurt. His turkeys showed no symptoms of flu but all 2,500 were slaughtered as a precaution.
"I lost 20 years worth of savings when they buried my birds," says Sitki, looking forlornly across the contaminated land. "I have no idea what to do now."
Like many men in Kiziksa, Sitki is sceptical there is avian flu here at all.
"No other animal here has fallen sick - just Mehmet's turkeys. So why should we suffer?" he asks.
But local officials are taking no chances.
"We are disinfecting everything," Mayor Ekrem Gokturk explains.
"When the cull is over we will spray the land from the air. But all these measures are just a precaution. There is nothing to worry about here."
Disbelief
Perhaps that is why the measures are so patchily applied.
There is a disinfection unit at the town entrance, but few vehicles are actually sprayed.
Some local farmers say the precautions are unnecessary
Access to Kiziksa is unrestricted - even to the affected farmland, and chickens, ducks and geese still wander the streets here freely. But their number is falling all the time.
As it grows dark, an elderly villager rides onto the central square on a bicycle carrying a white sack filled with wriggling chickens.
"I didn't want to go to prison so I thought it was wiser to bring the birds here," he says, throwing his sack into the back of a truck for gassing.
"But I did eat chicken for dinner tonight," he adds - almost defiant.
He is not the only one.
The vast majority of men in Kiziksa broke their Ramadan fast with chicken. They refuse to believe reports of bird flu, despite the laboratory reports.
"Why did no other birds die?" one man fumes. "Our healthy chickens are being slaughtered for nothing!"
Another insists Mehmet's turkeys were killed by a plague of fleas, instead.
The final test results are expected from Weybridge by Wednesday.
Until then, the Kiziksa sceptics have free rein. And Mehmet Eksen has a very nervous wait.
http://news.bbc.co.uk/1/hi/world/europe/4329712.stm