In the event of the unexpected appearance of a pandemic strain, vaccination is likely to be the only practical approach for limiting the impact of infection at a public health level. However, it will be a major challenge to produce adequate inactivated or CAV vaccine to protect the general population. Using recombinant DNA technology, an H5N1 reference virus has been produced for the development of an inactivated vaccine. Phase I studies of safety of an inactivated H5N1 vaccine produced by Sanofi Pasteur are planned for adults 18–64 years of age, and the U.S. Department of Health and Human Services plans to stockpile 2 million doses of this vaccine (73). Live attenuated H5N1 vaccine development is also under way for phase I trials in the United States. In parallel with these efforts, there is ongoing w ork to use mutant viral proteins, such as H5 that lacks the polybasic cleavage site, to reduce the virulence of H5N1 vaccine strains so that these can be efficiently propagated in eggs for vaccine production. Av ariety of vaccine approaches using dead virus to broaden immune protec- tion have been pursued in animal models of influenza, mainly rodents, ferrets, and primates. Dead vaccines have several advantages over live vaccines, including the potential to use recombinant antigens, avoidance of the time-consuming attenua- tion and propagation of live virus, safety of vaccination in immunocompromised hosts, and less reliance on a “cold chain” for vaccine stability. However, dead vac- cines using adjuvants currently approved for human use (alum or MF-59) usually have lower immunogenicity than live attenuated vaccines, particularly for T cell immune responses, such as CTLs. A universal influenza A dead-vaccine strategy based on antibody-mediated pro- tection against epitopes of the small, conserved, extracellular domain of the M2 protein has been proposed (78). However, a dead vaccine that induced not only high levels of neutralizing antibody to surface proteins but also CTLs against well- conserved antigens derived from internal viral proteins might provide superior pro- tection in an epidemic or pandemic. In the event that neutralizing antibody failed to block infection, CTLs would serve as a backup source for early immune protec- tion. This broad immune response might be achieved by including an adjuvant that effectively activates myeloid dendritic cells for the presentation of neoanti- gens to CD4 and CD8 T cells. In a recent human phase I study, vaccination with dead influenza vaccine mixed with DNA oligonucleotides containing unmethy- lated CpG motifs, which activate TLR9, only modestly increased immunogenicity (79). However, TLR9 is mainly expressed by plasmacytoid dendritic cells and not myeloid dendritic cells (80). Therefore, the pursuit of other adjuvants that effec- tively activate myeloid dendritic cells remains an attractive strategy to improve dead-vaccine immunogenicity in humans.
Avian flu has been around for a long time in wild birds. It started getting noticed by poultry farmers as far back as the early 1900s.
But the potent flu virus known as H5N1 wasn't discovered until 1997, when it suddenly surfaced on a goose farm in China. H5N1 attracted attention because birds became sick so swiftly, and such a great many died. Since that time, H5N1 has spread to over 40 countries in Asia, Africa and Europe.
There are a few direct and indirect ways for H5N1 to spread once it strikes a domestic flock of birds. But how is the virus introduced to commercial poultry in the first place? Often it comes from migratory wild waterfowl such as ducks or geese, who can carry the virus from place to place without getting sick themselves. That's why scientists often call these wild birds "reservoirs" for the virus.
997: In Hong Kong, avian influenza A (H5N1) infected both chickens and humans. This was the first time an avian influenza virus had ever been found to transmit directly from birds to humans. During this outbreak, 18 people were hospitalized and 6 of them died.
The virus appears to cause no symptoms in birds and possibly pigs
The scientists who inspected the genes of the virus samples sent to Chinese labs say H7N9 appears capable of infecting some birds without causing any symptoms. That means it could be a "silent spreader" that’s moving among birds or pigs undetected
Without obvious outbreaks of flu in chickens, wild birds or pigs, that could make it difficult to pinpoint the original infection source, as well as track its spread. That wasn’t the case with H5N1 bird flu, which caused obvious signs of illness during outbreaks, allowing farmers to perform mass culls to stop the virus’ spread.
It also makes it harder to narrow down the species that’s fuelling the virus’ spread.
"At the moment, we can't see where this virus is coming from. We don't know yet what animal source is feeding this." Wendy Barclay, a flu virology expert at Britain's Imperial College London recently told Reuters.
And, if there were no obvious symptoms in birds or pigs "nobody recognizes the infection in animals around them. Then the transmission from animal to human may occur," Tashiro told Reuters.
"In terms of this phenomenon, it's more problematic."
There have now been 18 identified cases of infection of the H7N9 strain.
Six people have died, and the World Health Organization (WHO) said a further 8 cases were "severe".
In response, Chinese authorities have extended a ban on poultry trading to the city of Nanjing, having earlier closed markets in Shanghai.
China's state-run news agency Xinhua said authorities had already culled tens of thousands of birds at two Shanghai poultry markets, where traces of the virus had been found earlier in the week.
Local officials in Nanjing said the virus had not been detected at its poultry markets, suggesting the trading ban is a precaution.
Live bird markets are the traditional way that poultry is sold in China.
In a statement, the WHO reiterated that there was not yet any evidence of human-to-human transmission of the virus.
But it said that more than 500 "close contacts" of the 18 people infected were being closely monitored.
Know the Signs of Avian (Bird) Flu H7N9
Most of the people identified with the new bird flu have had symptoms of severe pneumonia such as chest congestion, difficulty breathing, fever, and severe cough. However the case reports are so recent that experts don’t believe they have a full picture of all possible symptoms.
Yesterday the CDC began issuing guidance to public health clinics and hospitals in the U.S. on how to test for the H7N9 virus. In a teleconference yesterday afternoon, CDC officials said they have already developed a diagnostic test that’s available for use on “travelers with suspicious illnesses.”
There is currently no vaccine to prevent H7N9. At this time, we do not know the source of this virus. CDC is repeating its standard advice to travelers and Americans living in China to follow good hand hygiene and food safety practices and to avoid contact with animals.
Do not touch birds, pigs, or other animals.
Do not touch animals whether they are alive or dead.
Avoid live bird or poultry markets.
Avoid other markets or farms with animals (wet markets).
Eat food that is fully cooked.
Eat meat and poultry that is fully cooked (not pink) and served hot.
Eat hard-cooked eggs (not runny).
Don’t eat or drink dishes that include blood from any animal.
Don’t eat food from street vendors.
Practice hygiene and cleanliness:
Wash your hands often.
If soap and water aren’t available, clean your hands with hand sanitizer containing at least 60% alcohol.
Don’t touch your eyes, nose, or mouth. If you need to touch your face, make sure your hands are clean.
Cover your mouth and nose with a tissue or your sleeve (not your hands) when coughing or sneezing.
Try to avoid close contact, such as kissing, hugging or sharing eating utensils or cups, with people who are sick.
See a doctor if you become sick during or after travel to China.
See a doctor right away if you become sick with fever, coughing, or shortness of breath.
If you get sick while you are still in China, visit the US Department of State websiteExternal Web Site Icon to find a list of local doctors and hospitals. Many foreign hospitals and clinics are accredited by the Joint Commission International. A list of accredited facilities is available at their website (www.jointcommissioninternational.orgExternal Web Site Icon).
Delay your travel home until after you have recovered or your doctor says it is ok to travel.
If you get sick with fever, coughing, or shortness of breath after you return to the United States, be sure to tell your doctor about your recent travel to China.
Seeking the cause and a vaccine
"We don't know yet where the humans got their virus from," said Dr. Joseph Bresee, who heads the epidemiology and prevention branch in the U.S. Centers for Disease Control and Prevention's (CDC) influenza division.
The virus has not been shown to spread easily between humans, he added.
The CDC, based in Atlanta, is working closely with Chinese authorities trying to find the source of the human infections, Bresee said.
"There are lots of things happening at CDC to prepare for this virus," Bresee said. "State health departments are readying themselves just in case," and researchers are working on developing a vaccine for this strain, he said.
With confirmation that a sixth person has died from a mysterious avian-borne virus, Chinese officials escalated their response on Friday, advising people to avoid live poultry, sending virologists to chicken farms across the country and slaughtering more than 20,000 birds at a wholesale market in Shanghai where the virus, known as H7N9, was detected in a pigeon.
United Nations, Rabi'I 17, 1434, Jan 29, 2013, SPA -- The world risks a repeat of the 2006 bird flu outbreak unless surveillance and control of this and other dangerous animal diseases is strengthened globally, the U.N. Food and Agriculture Organization said Tuesday.
"The continuing international economic downturn means less money is available for prevention of H5N1 bird flu and other threats of animal origin. This is not only true for international organizations but also countries themselves," the agency's chief veterinary officer Juan Lubroth said in a statement.
The H5N1 virus still exists in some countries in Asia and the Middle East...
Beijing, Jumada I 19, 1434, Mar 31, 2013, SPA -- Three cases of human infection with H7N9 avian influenza have been detected recently in Shanghai and Anhui Province, and two of them have died, the other being in a critical condition, the National Health and Family Planning Commission said Sunday.
The victims include an 87-year-old male in Shanghai who got sick on Feb. 19 and died on March 4, a 27-year-old male in Shanghai who became ill on Feb. 27 and died on March 10, and a 35-year-old female in Chuzhou City of Anhui who became ill on March 9 and is now in a critical condition...