The H5N1 strain of influenza - often referred to as bird flu - is first known to have jumped from chickens to humans in 1997. Since 2004 it has ripped through poultry and wild bird populations across Eurasia, and had a 53% mortality rate in the first 147 people it is known to have infected. Health authorities fear this strain, or its descendent, could cause a lethal new flu pandemic in people with the potential to kill billions.
Flu has been a regular scourge of humanity for thousands of years. Flu viruses each possess a mere 10 genes encoded in RNA. All of the 16 known genetic subgroups originate in water birds, and especially in ducks.The virus is well adapted to their immune systems, and does not usually make them sick. This leaves the animals free to move around and spread the virus - just what it needs to persist.
But sometimes a bird flu virus jumps to an animal whose immune system it is not adapted to.
A few days ago I posted on a story in Hong Kong's The Standard, in which Dr. Margaret Chan estimated that 20 percent of the populations of "some countries" could be affected by a global H5N1 pandemic.
Since it's a very quiet flu news day, I'll take the time to explore this estimate. What follows is idle speculation, to be taken as such.
Actually, the implications are startling, and that's for only 20%. What if she's
Although the rate of reported human cases is higher in the winter, the summer reports signal widespread infections, which persist over the summer months.
The results in Egypt parallel the results in Europe, which has reported H5N1 in wild birds and poultry in June and July. These reports support endemic H5N1 in both regions, as well as in western Africa, where confirmed outbreaks are reported in Ghana and Togo.
Thus, after migrating into these regions in the fall of 2005, H5N1 has become established in resident wild bird populations, leading to infections reported throughout the year. Reports of H5N1 in Siberia, suggest additional positives will be reported in Europe, the Middle East, and Africa when these birds migrate to the south, beginning next month.
A flu pandemic could probably not be contained and defeated on egg-based production, because the production takes too long
and eggs don't grow on demand.
Cell culture based systems, however, could be rapidly expanded and scaled up in times of emergency -
which also points to one potential downside of tissue culture production: the up-front costs for operational readiness of such plants (with its huge fermenters) are much higher than the costs for egg-based systems,, and the yield may be slightly slower.
Mammalian cell-based flu vaccine production may have even more benefits:
potential impurities in eggs (antibiotics, other viruses) may cause sterility problems.
There is also a risk of allergies against egg albumin. None of these risks exists in cells.
Last but not least,
the strains grown in cell cultures equal the original clinical isolates, while the growth of epidemic viruses in eggs result in variants that are antigenically distinct from the original viruses.
Emerging endemic viruses sometimes do not grow at all in eggs.
Virus grown in mammalian cell culture is therefore more representative of the circulating wild type virus than that grown in eggs.
So, what is the new Pennsylvania based vaccine plant doing?
...amid the warren of stainless-steel tubes and vats, the plant will still make vaccine the old-fashioned way: with chicken eggs.
They have incubated flu vaccine reliably since 1935. And the plant will need 600,000 eggs a day at full capacity. Sanofi buys what it needs and more from dedicated egg suppliers, to assure an ample supply.
Sanofi senior vice president Wayne Pisano, who oversees vaccine sales, described the process as tried-and-true, and said the emerging cell-culture-based method has not been perfected for making the millions of doses needed.
Tamiflu has been implicated in the suicide and death of several Japanese
children. This antiviral has been widely used in Japan for a number of years.
In an unprecedented case, a Japanese family is now suing a health ministery body that contended that Tamiflu had nothing to do with this child's death.
The suit comes months after Japanese health authorities ordered doctors not to prescribe Tamiflu, which is manufactured by the Swiss drug firm Roche and sold in Japan by Chugai Pharmaceutical, to patients aged 10-19 following dozens of deaths and injuries among teenagers over the past six years.
More than 1,300 people have exhibited neuropsychiatric symptoms since Tamiflu went on sale in Japan in 2001, of whom 71 have died.Twenty-seven, most in their teens, fell from buildings.
Last month the health ministry announced new clinical trials to establish whether the antiviral could cause delirium, delusion and other neuropsychiatric symptoms. The ministry had previously ruled out any link.
This is a big, big problem.
Tamiflu is a common flu treatment here, and is widely used where H5N1 is endemic. It is the drug stockpiled by many countries to combat a potential bird flu pandemic.
Imagine a United States military lab in Cairo that was not closed, even during the 6-Day War of 1967 or the Yom Kippur War of 1973! NAMRU-3 is an amazing lab, where bird flu samples are tested and certified to the WHO. It is a testament to the abilities of the United States Navy and the government at large, and is also a testament to the Egyptian government's recognition of its role in world health and world peace.
So it's true then. It is HPAI, and not low path avian flu.
NEW DELHI (Thomson Financial) - India's government has reported an outbreak of bird flu among poultry, the first outbreak since it declared itself free of the disease last August.
The government's department of animal husbandry said it had started to cull tens of thousands of birds in the northeastern state of Manipur, where 132 of 144 chickens at a small poultry farm died earlier this month.
The health ministry said it had rushed "rapid response teams" to test 450,000 people for possible symptoms of bird flu within a ten-kilometre radius of the infected zone in Manipur's Imphal state capital district.
...the infected birds died within a six-day period from July 7.
"Samples taken from the dead as well as the remaining stock are positive" for highly pathogenic H5 avian influenza, Sohony said, adding a "containment process" was underway to prevent the disease spreading.
...21 family members directly exposed to the infected chickens in Chingmeirong were being given the anti-viral drug Oseltamivir.
"So far none has showed any symptoms of infection," he said.
"We have sent 40 medical teams to survey 80,000 households in a timeframe of ten days," Chowdhury said.
Experts are unsure why this season's flu is so severe. "There is a significant amount of influenza activity and an increase in the number of cases presenting to emergency and in laboratories this year," said Dr Dominic Dwyer, a medical virologist from Westmead Hospital. "It has been the worst we've had in several years."
Dr Dwyer said it was difficult to know why so many people were falling victim to influenza viruses, the symptoms of which include fever, headache, sore throat and severe tiredness.
"It's hard to know whether this is due to a particularly virulent strain, but certainly there have been some deaths in the past few weeks."
The senior medical virologist at the Prince of Wales Hospital, Professor Bill Rawlinson, said the hospital was mainly seeing a virus known as A/Wisconsin-like virus, which is present in the flu vaccine. "We hope the vaccine is protecting well and that people are getting it," he said.
"The reality is if you do get the flu, you are often out for two weeks and even if you have had the injection it can [only] give you partial protection."
India is managing a massive undertaking with the screening of thousands of people for H5N1 infection, and the culling of tens of thousands of poultry. Luckily there have been no human cases found thus far.
Because this infection had to come from somewhere, as no disease exists in a vacuum, they have to be looking for a source of infection as well.
This is just one remote area of a hugh country. What if they have to do this in several areas at once. It is hard to imagine the amount of resources that would be needed, and the expense. Look at the numbers. Can poor countries afford this type of effort for long without international assistance? Will India be able to do what must be done if it requires weeks of effort?
The health directorate sent 40 medical teams to examine people and collect blood samples from those living in and around Chingmeirong, the Imphal suburb where the affected farm is located. Health workers did not find a single instance of bird flu passing to humans-the H5N1 strain can be fatal-in the affected zone.
All the 234 blood samples tested till this evening were found negative for bird flu.
Health secretary P. Vaiphei said 59 people were found to have acute respiratory infection or fever caused by viruses other than the avian flu strain. "As many 3 lakh people of 60,000 households will be covered during the 10-day screening campaign. We have so far checked 10,251 people from 1,754 households."
The veterinary department culled 16,000 chickens on the second day of its operation in 32 villages of Imphal West and East districts.
Another 34 villages will be covered tomorrow.
It is estimated that nearly 1,60,000 chickens in 128 small poultry units within the 5-km zone of the infected farm at Chingmeirong would need to be culled.
The "hot zone" also has a population of about 28,000 ducks.
Veterinary director Th. Dorendro Singh said 20 per cent of the 86 villages selected for the culling had already been covered and the situation was well under control.
Yesterday, 9,472 chickens were killed within the 5-km radius of the Chingmeirong farm.
"We had sent only 17 rapid-response teams on the first day. We increased the strength of the five-member teams to 33 today. We hope to complete the culling operations within the next four days," an official at the bird flu control room said.
Farmers are hiding their poultry as they have done in almost every other country where mass culling has occurred, not to mention the house to house searches in Germany. At least some of the people are helping.
It is interesting that they are taking blood samples from the residents of the
area instead of doing just throat swabs to look for flu. This can only mean that
they are looking for antibodies indicating infection from H5N1 even if asymptomatic. That would be news if they found any asymptomatic humans. But, it might not be good news.
GUWAHATI (Reuters) - More than a dozen poultry farmers in country's bird flu-hit northeast have been caught trying to smuggle flocks of chickens out of the quarantine zone, police said on Saturday.
Local residents were helping police stop people sneaking chickens and poultry products out from within a 5 km radius of a small farm at Chingmeirong village in Manipur state, the site of India's latest bird flu outbreak this week.
The lesson explains to students the many reasons why they should know about the highly pathogenic H5N1 avian influenza virus that currently is spreading overseas and what it would mean if it is detected in the United States.
"Understanding Avian Influenza will challenge teachers and their students to think about the many impacts highly pathogenic H5N1 avian influenza already has had throughout the world and why it's critical that the spread of this virus be stopped."
Because the highly pathogenic H5N1 avian influenza strain has infected thousands of domestic and wild bird populations in more than 50 countries and is one of the few avian influenza viruses to have crossed the species barrier to infect humans, it is the most deadly of those that have crossed the barrier.
indigo girl
5,173 Posts
From crofsblogs,
The Implications of 20 percent:
http://crofsblogs.typepad.com/h5n1/2007/07/the-implication.html
Actually, the implications are startling, and that's for only 20%. What if she's
wrong, and it's a higher percentage?