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EINet Alert ~ Nov 23, 2007
*****A free service of the APEC Emerging Infections Network*****
APEC EINet News Briefs offers the latest news, journal articles, and notifications for emerging infections affecting the APEC member economies. It was created to foster transparency, communication, and collaboration in emerging infectious diseases among health professionals, international business and commerce leaders, and policy makers in the Asia-Pacific region.
In this edition:
- Global: Cumulative number of human cases of avian influenza A/(H5N1)
- UK: Defra offers licenses for movement of bird by-products
- UK: Second case of H5N1 confirmed in Norfolk poultry farm
- UK: 68,000 birds to be slaughtered in sixth Suffolk/Norfolk cull
- UK: Economic impact of avian influenza H5N1 infection
- Saudi Arabia (Riyadh): Random inspections find 4 cases of avian influenza H5N1
- Saudi Arabia: Excerpts from OIE report on avian influenza H5N1
- Yemen: Increased vigilance by Yemeni authorities after reports of dead poultry
- Bangladesh: Re-emergence of avian influenza in poultry; avian influenza preparedness
- Thailand: Mass poultry deaths raise fears of avian influenza H5N1 outbreak
- Hong Kong: Wild bird suspected of H5 avian influenza infection
- Viet Nam: More information on Taiwanese man suspected with avian influenza
- Viet Nam (Ben Tre): Avian influenza H5N1 kills young ducks in the Mekong delta
- USA: Inviragen wins $600,000 NIH grant
- Avian/Pandemic influenza updates
- Study finds greater, later role for antivirals in flu patients
- Sharing H5N1 Viruses to Stop a Global Influenza Pandemic
- Transmission of the Highly Pathogenic Avian Influenza Virus H5N1 within Flocks during the 2004 Epidemic in Thailand.
- Differences in public emotions, interest, sense of knowledge and compliance between the affected area and the nationwide general population during the first phase of a bird flu outbreak in Israel
- Study says wild birds unlikely to bring H5N1 to Americas
- APEC Center for Technology Foresight: Technology Roadmapping Workshop
- A Description of the Process of Seasonal and H5N1 Influenza Vaccine Virus Selection and Development (WHO)
Global: Cumulative number of human cases of avian influenza A/(H5N1)
Economy / Cases (Deaths)
Total no. of confirmed human cases of avian influenza A/(H5N1), Dec 2003 to present: 335 (206).(WHO 11.12.07
Avian influenza age distribution data from WHO/WPRO:
WHO's maps showing world's areas affected by H5N1 avian influenza (last updated 11.21.07):
WHOs timeline of important H5N1-related events (last updated 11.5.07):
UK: Defra offers licenses for movement of bird by-products
Defra has made available general licenses to address immediate issues relating to the movement of bird by-products and mammals in the zones in place for Avian influenza. Bird by-products may now be moved freely between zones and to the unrestricted parts of the country. Mammals may move directly to or from premises where poultry or other captive birds are kept in the Protection or Surveillance Zones. Movements of hatching eggs may also be permitted under specific license available from Animal Health. All movements are subject to strict adherence to license conditions, including biosecurity measures. The national ban on bird gatherings and movement restrictions in the zones remain firmly in place. It is essential that poultry keepers are vigilant in checking their birds and report signs of notifiable disease immediately.
Also, the decision has been made to reclassify the cull at one of the four dangerous contacts premises (identified on 14 Nov 2007) to a slaughter on suspicion of Avian Influenza. During preparation for the cull at this premises, which is in the existing Protection Zone, avian notifiable disease could not be ruled out. Samples have been taken for laboratory testing. There is no timetable for when these results will be received. The strain of Avian influenza present at the Infected Premises near Diss is similar to that found in Germany, France and the Czech Republic during the summer .
A full epidemiological investigation is underway and all avenues into the origin of this outbreak are being investigated. Surveillance of poultry premises in the Protection Zone is underway, surveillance of wild birds has been increased in Norfolk and Suffolk and the national targeted wild bird surveillance programm is ongoing.
UK: Second case of H5N1 confirmed in Norfolk poultry farm
In total, more than 28,000 birds were slaughtered following the suspected outbreak of H5N1, a variant of the disease capable of being transmitted to humans. The cull of poultry on four sites suspected of being infected ended on 18 Nov 2007. A 3 km protection zone and a 10 km surveillance zone have been set up and the farm is co-operating with vets. Defra are still waiting for the results of culls at two farms in Norfolk Stone House, West Harling, and Bridge Farm, Pulham.
Fred Landeg, the acting chief veterinary officer, said the latest results highlight the importance of vigilance from poultry farmers. He added: "It is essential they practice the highest levels of biosecurity and report any suspicions of disease to their local Animal Health office." A national and a local disease control center have been established in Bury St Edmunds, with text messages sent to all bird keepers nationwide especially those in zones on the poultry register.
UK: 68,000 birds to be slaughtered in sixth Suffolk/Norfolk cull
The move comes amid fears that workers at the farm have traveled to other farms that are deemed a flu risk. More than 28,600 turkeys, ducks and geese have already been slaughtered.
Acting chief veterinary officer Fred Landeg said the move is based on new information about exposure risk and stressed that all poultry keepers must immediately report any signs of the disease. The sixth cull will include 56,000 ducks, 9,000 turkeys and 3,000 geese.
UK sales of poultry are worth BP 3.5 billion [USD 7,167,651,365] at retail
Fresh chicken sales are worth BP 2.1 billion [USD 4,300,590,819]
UK turkey market worth BP 375 million [USD 767,962,646] to BP 400 million [USD 819,160,156]
Fresh turkey sales account for BP 240 million [USD 491,496,093]
There are 860 million chickens produced a year, giving 1.3 million tons of poultry meat
There are 17 million turkeys reared in Britain producing 185,000 tons of meat
There are 19 million ducks reared producing 44,000 tons of meat
About 100,000 geese are reared for the Christmas market East Anglia accounts for a third of the UK poultry production
There are 1200 poultry farmers and 25 million birds of which 5 million are turkeys in the restricted area of Suffolk and parts of Norfolk
In the 10km surveillance zone there are 90 poultry keepers with 3 million birds
The incubation period for avian flu in turkeys is 3 to 5 days though it can be 5 to 7 days in other species
The survival rate of the virus in feces can vary from days to week depending on temperature and humidity
Up to 27,000 turkeys, 1200 ducks and 500 geese have been culled or are awaiting slaughter
The cost of animal infections is thought to have cost the government and taxpayers more than GBP 120m [USD 245.8m] this year .
(ProMED 11.17.07 & 11.20.07)
Saudi Arabia (Riyadh): Random inspections find 4 cases of avian influenza H5N1
"There are 85 poultry shops in this market and each will have a minimum of 1,000 birds. The team plans to cull the birds and disinfect the whole area to stop the virus from spreading," said Soliman Al-Buthi, general manager of the Environmental Health Department at the Riyadh Municipality. He added that the municipality is working with the emergency team to tackle the problem.
Al-Buthi stressed that the situation is under control and called on members of the public to help the authorities tackle the problem. According to a statement issued 19 Nov 2007 by Muhammad Al-Sheha, undersecretary at the Ministry of Agriculture, the authorities have so far culled 222,000 birds in Al-Kharj, Durma, Muzamiyah, and Al-Hayati.
Bird flu was discovered earlier this year in peacocks, turkeys, and parrots at a house in the east of the Kingdom. This led to a number of birds in the area being destroyed. The recent outbreak of the disease has led to poultry farm workers being examined by Ministry of Health doctors. All workers have so far tested negative.
"Farm workers were brought to hospitals in their respective regions and were examined for bird flu. Clinical examinations revealed that none of them had bird flu," Khaled Al-Mirghalani, Ministry of Health spokesman, said 19 Nov 2007. "We have given flu vaccinations to all those who were tested," he added.
Al-Mirghalani said that the kingdom has adequate stock of Tamiflu tablets for use in case of emergencies. He added that there are no vaccinations against bird flu and Tamiflu tablets are administered as a treatment.
"We're fully equipped with laboratories and drugs to treat suspected patients, if any," said Mirghalani, adding that citizens need to immediately report suspected cases. He also advised people to keep away from birds, not to hunt them, not to touch dead birds without gloves, and to only consume chicken and eggs that are well cooked. The Agriculture Ministry has called on poultry farmers to strictly implement safety regulations.
Saudi Arabia: Excerpts from OIE report on avian influenza H5N1
Outbreak 2: Dhurma, Ar Riyad
Outbreak 3: Al-Muzahmiyah, Ar Riyad
Outbreak 4: Al-Kharj, Ar Riyad
Yemen: Increased vigilance by Yemeni authorities after reports of dead poultry
"We received several reports from farmers during the past few days about the death of birds," Ghalib al-Eryani of the Agriculture Ministry said. He said concerns were high that the birds were infected by the H5N1 strain of bird flu virus. "Procedures have been taken to combat the strain, and imports from infected countries were banned," the official said.
Al-Eryani said teams were sent to poultry farms to make necessary tests. Neighboring Saudi Arabia has culled more than 200,000 birds since mid-November 2007 after the outbreak of the H5N1 virus in a central region of the kingdom.
Bangladesh: Re-emergence of avian influenza in poultry; avian influenza preparedness
Avian flu has re-emerged in Bangladesh after 4 months, with 5 reported new outbreaks in poultry farms across the country since Oct . The contagious viral disease was first detected in Bangladesh in Mar 2007. Since then there have been 55 outbreaks in 19 of the country's 64 districts. To halt a further spread of the virus, more than 250,000 chickens have been culled since the original outbreak.
"At 795 persons per square km, Bangladesh has the highest population density in the world. This close proximity of human beings is a risk element for transmission of any contagious disease like flu," Nazrul Haq, a member of the government's technical working group on avian influenza risk, said.
Further compounding the problem is the prominent role of poultry farming. Almost all rural households keep chickens as a source of cheap protein, with about 2.4 million rural women depending on backyard chicken farming as their only source of livelihood. Even well-off families in Bangladesh raise a few chickens to supplement their income. As a result, communicating appropriate biosecurity practices such as separating domestic flocks from wild ones, hygienic slaughtering and waste disposal, use of masks while cleaning chicken coops, disinfection before and after working in poultry farms, as well as the use of personal protective equipment is already proving difficult.
"Behaviors don't change overnight," Habibur Rahman of the Bangladesh Agricultural University said. "Most of these farms do not maintain necessary sanitary and preventive measures essential for keeping chicken safe from infection," he added, estimating that there were well over 100,000 small and medium-sized farms in the country.
In July , the Bangladesh government signed an agreement worth USD 16 million with the International Development Association, the World Bank's concessionary arm, to minimize a possible bird flu threat. The Avian Influenza Preparedness and Response Project supports the government's National Avian Influenza and Pandemic Influenza Preparedness and Response Plan and is designed to control infections in domestic poultry, while at the same time formulating plans to control and respond to possible human infections, especially an influenza epidemic. Meanwhile, officials in Bangladesh have also taken measures, including a ban on the import of poultry-related products from affected countries, monitoring of imported day-old chicks from non-affected countries, the control of illegal poultry product trading, an improvement of laboratory facilities, as well as forming a national task force representing relevant stakeholders including the private sector.
The government has imposed a 1km restricted area around any confirmed infection point and all poultry within the area is culled, while strict controls are imposed on the movement of poultry and poultry products within a 10km radius. According to Abdul Motaleb, director of the government's department of livestock, the proper disposal of dead birds and contaminated materials such as eggs and feces is also now ensured, while surveillance and monitoring have been strengthened.
"We have trained 320,000 community volunteers on bird flu prevention. They are going from door-to-door in rural Bangladesh to communicate and train women on safe and sanitary practices that can prevent bird flu," Motaleb added. There have been no cases of human infection in Bangladesh.
Thailand: Mass poultry deaths raise fears of avian influenza H5N1 outbreak
Permanent Secretary Prat Boonyawongvirot said he had urged volunteers to inform health officials immediately if any poultry perished. Then theyll be checked for the virus, he said. The ministry also stressed that children should stay away from chickens or birds that fell ill or died under inexplicable circumstances.
Nakhon Sawan has witnessed suspicious mass deaths of fighting cocks in Nong-pangpuay village of Kaoliew district. Their symptoms were similar to bird flu. Headman Yongyuth Thongchoop said officials are trying to investigate the cause of the mass deaths of chickens in the area and will destroy the carcasses. However, villagers protested against officials who tried to get samples of dead chickens to test in the lab, because they do not want their prized possessions to be culled, he said. Phin Khanjiek, a villager, said he wants authorities to confirm the virus infection before sacrificing his fighting cock because he had bought it at a high price.
Dr Thawat Suntrajarn, director-general of the Disease Control Department, said the Bureau of Epidemiology was monitoring 2,036 patients suffering from general flu and pneumonia admitted to hospitals across country. No bird-flu cases have been reported in those patients, and the ministry has not received any news of bird-flu infections in humans for the past 14 months.
[If confirmed, the Thai outbreak will become one more manifestation of what seems to be an unfolding seasonal trend, with upsurge of H5N1 in Asia (Viet Nam, Bangladesh, Saudi Arabia, Pakistan, Myanmar, Indonesia) and Europe (England) as temperatures fall and winter is approaching].
Hong Kong: Wild bird suspected of H5 avian influenza infection
This is the first wild bird suspected to be infected by the virus at the onset of this winter season [2007-2008]. The bird was collected in Tuen Mun Park 18 Nov 2007 and died the next day. There are no chicken farms within 3 km of where the bird was found. Poultry farmers have been reminded to take precautionary and biosecurity measures against bird flu. Farmers, pet bird shop owners, pet poultry license holders, and racing pigeon owners have been informed to take proper precautions.
The department will inspect poultry farms and the wholesale market to ensure proper precautions against bird flu have been implemented. Close surveillance of wild birds will continue. While vigilance over imported poultry and live poultry stalls will continue, illegal poultry and bird imports will be deterred and health education bolstered.
Viet Nam: More information on Taiwanese man suspected with avian influenza
The father of the suspected case of avian influenza was admitted to hospital in Taiwan 6 Oct 2007. He was a 58-year-old man with long history of smoking. In October, he was admitted because of increased frequency of cough. Chest x-ray showed left upper lobe, posterior segment consolidation that is suspicious of tuberculosis. After treatment with antibiotics, the patient was discharged. He has been well since discharge. At this time, it is believed that there is no epidemiological association between the illnesses of the father and son.
Viet Nam (Ben Tre): Avian influenza H5N1 kills young ducks in the Mekong delta
USA: Inviragen wins $600,000 NIH grant
Inviragen Inc., a Colorado developer of vaccines with an office in Mount Horeb, has received a two-year $600,000 grant from the National Institutes of Health for the development of a safe and effective avian influenza vaccine. The Small Business Technology Transfer award supports Inviragen's collaboration with the University of Wisconsin-Madison on the project, the company said. The grant will fund the construction and testing of new vaccines designed to protect against the highly pathogenic H5N1 avian influenza virus. Inviragen also is developing vaccines to protect against dengue fever, West Nile virus and smallpox.
Avian/Pandemic influenza updates
- UN: http://www.un-influenza.org/ : latest news on avian influenza. Also, http://www.irinnews.org/Birdflu.asp provides information on avian influenza.
- WHO: http://www.who.int/csr/disease/avian_influenza/en/index.html
- UN FAO: http://www.fao.org/ag/againfo/subjects/en/health/diseases-cards/special_avian.html
- OIE: http://www.oie.int/eng/info_ev/en_AI_avianinfluenza.htm
- US CDC: http://www.cdc.gov/flu/avian/index.htm
- The US governments web site for pandemic/avian flu: http://www.pandemicflu.gov/
- Health Canada: information on pandemic influenza: http://www.influenza.gc.ca/index_e.html
- CIDRAP: http://www.cidrap.umn.edu/
- PAHO: http://www.paho.org/English/AD/DPC/CD/influenza.htm
- US Geological Survey, National Wildlife Health Center Avian Influenza Information:
Updated 16 Nov 2007.
(UN; WHO; FAO, OIE; CDC; Health Canada; CIDRAP; PAHO; USGS)
Study finds greater, later role for antivirals in flu patients
Adults who are hospitalized with serious seasonal influenza infections are more likely to survive if they receive antiviral medications, and older patients may benefit even if treatment is delayed until more than 48 hours after their first symptoms, according to a new study by Canadian researchers.
The standard advice about antiviral treatment for flu based on previous studies involving relatively young, otherwise healthy adults is that it must begin within 48 hours after onset of symptoms to be effective. But the new findings, published in the early online Dec 15 edition of Clinical Infectious Diseases (CID), suggest the virus may behave differently in an older, sicker population, giving antiviral medications a role later in the illness course.
The US CDC classifies people aged 65 and older among the groups vulnerable to serious complications of influenza. In the US each year, seasonal influenza is linked to about 200,000 hospitalizations and 36,000 deaths, according to a Nov 12 press release from the Infectious Diseases Society of America (IDSA), which publishes CID.
"Influenza causing hospital admission is more common than most people think," said the study's lead author, Allison McGeer. "We will save lives if we recognize and appropriately treat influenza in patients being admitted to the hospital."
The Toronto-based researchers reviewed medical data from 327 adults who were hospitalized for laboratory-confirmed influenza between Jan 2005 and May 2006 to explore how antiviral medications influenced the patients' treatment outcome. The study was funded by a grant from Hoffman-La Roche, the maker of the antiviral drug oseltamivir (Tamiflu), but the authors state the company had no role in designing, conducting, or reporting the study.
Among the study group, 75% (245) of patients had an underlying chronic illness and 71% (216) had received their annual flu vaccine. The median age of the patients was 77 years (range, 15 to 98). Thirty-two percent (106) of the patients were prescribed antiviral drugs; three received amantadine and 103 got oseltamivir. Of the 100 patients for whom more detailed oseltamivir treatment data was available, 71 were treated starting more than 48 hours after their flu symptoms began.
The researchers found that antiviral medications reduced the risk of death by 79% (odds ratio, 0.21; 95% confidence interval, 0.06 to 0.80). The treatment did not reduce the length of hospital stay, however. The finding that antiviral treatment begun more than 48 hours after symptom onset was beneficial for older patients does not contradict other findings that for otherwise healthy adults the drugs are effective only when given sooner, the researchers write. A robust immune response in healthy patients quickly clears the virus from the body, and late antiviral treatment isn't helpful.
"However, patients with severe immuno-compromise may not control viral replication for many days, and little is known about the time course of viral load in older patients at risk of influenza complications," the authors report.
They conclude that their findings support the use of antiviral medications in hospitalized patients, but McGeer said the drugs should be prescribed only when patients really need them.
"As with antibiotics, there is a risk for selection for antiviral resistance, and it is important to use the medications only where there is a clear benefit," she said. Anne Moscona, an antiviral expert at Weill Cornell Medical College, said the CID study findings have the potential to change how physicians manage flu patients. More physicians should be testing for influenza and prescribing antiviral treatment when they find it in hospital patients, she said.
The authors of the CID study say the rates of disease they found varied by medical facility and that the number of lab-confirmed flu cases was lower than what they had expected for the number of hospital admissions and population size.
Moscona said, "If we test more, we'll identify more, and people will get more antivirals as opposed to antibiotics."
Frederick Hayden, an antiviral expert with the WHO, said that the study's findings on the benefits of later antiviral treatment were compelling. "It's clear from this experience now that there seems to be a benefit, even with later treatment," he said.
McGeere said her team's findings don't diminish the importance of flu vaccination. "Considerable morbidity and mortality due to influenza remain. We need and people are working on better vaccines," McGeer said. "Until we get them, we can help people by diagnosing and treating disease."
McGeer A, Green KA, Pleveshi A, et al. Antiviral therapy and outcomes of influenza requiring hospitalization in Ontario, Canada. Clin Infect Dis 2007;45(15 Dec)
Sharing H5N1 Viruses to Stop a Global Influenza Pandemic
Introduction: Although the threat of pandemic influenza, spawned by continuing avian influenza A (H5N1) epidemics, has dropped off the front pages, concern among experts continues to grow. At the end of 2005, only 17 countries had H5N1 outbreaks in chickens, ducks, or humans. As of September 2007, the virus has circulated in 60 countries, mutations have been reported (for example, in a patient in Turkey and another in Thailand), and virologists and public health officials nervously watch clusters of probable human-to-human spread of the virus, such as in Thailand in 2004 and Indonesia in 2006. For reasons not fully understood, most human cases and clusters of probable human-to-human transmission of H5N1 since January 2006 have occurred in Indonesia.
Recent studies have begun to characterize the mutations in H5N1 that may be a prerequisite for efficient human-to-human transmission. The world needs to monitor each new influenza virus in order to check for such mutations, which could transform H5N1 into a dangerous pathogen easily spread between people. How devastating might such a transformation be? In an age of globalization and commercial air travel, estimating how great a toll a lethal human-to-human influenza virus could inflict is difficult. Estimates of deaths from the last great bird-to-human flu pandemic of 1918 range from 50 to 100 million, which provides a glimpse of the global damage that could be caused by a pandemic influenza accelerated by 21st century globalization. . .
Transmission of the Highly Pathogenic Avian Influenza Virus H5N1 within Flocks during the 2004 Epidemic in Thailand.
Abstract: This present study is the first to quantify the transmission of avian influenza virus H5N1 within flocks during the 2004 epidemic in Thailand. It uses the flock-level mortality data to estimate the transmission-rate parameter (beta) and the basic reproduction number (R(0)). The point estimates of beta varied from 2.26/day (95% confidence interval [CI], 2.01-2.55) for a 1-day infectious period to 0.66/day (95% CI, 0.50-0.87) for a 4-day infectious period, whereas the accompanying R(0) varied from 2.26 (95% CI, 2.01-2.55) to 2.64 (95% CI, 2.02-3.47). Although the point estimates of beta of backyard chickens and fighting cocks raised together were lower than those of laying hens and broiler chickens, this difference was not statistically significant. These results will enable us to assess the control measures in simulation studies. They also indicate that, for the elimination of the virus, a critical proportion of the susceptible poultry population in a flock (i.e., 80% of the population) needs to be vaccinated.
Differences in public emotions, interest, sense of knowledge and compliance between the affected area and the nationwide general population during the first phase of a bird flu outbreak in Israel
Methods: We conducted a telephone survey among two randomly selected, representative samples of adults. One sample involved 500 adult residents of the nationwide area; and the other sample involved 103 adult residents of the affected area during the first phase of the outbreak. We measured perceived emotions, interest, sense of knowledge and compliance. We analyzed the differences in these parameters between the affected area and the nationwide population using chi-square and t-test analysis. A p value of less than 0.05 was considered to be statistically significant.
Results: The compliance for using measures of precaution was high and not significantly different between the affected area and the nationwide population. The interest in bird flu and the sense of knowledge were significantly higher in the affected area compared to the nationwide population (p<0.05). A misconception of a high human to human transmission was significantly higher in the nationwide population compared with the affected area (p<0.05). The levels of stress and fear perception were significantly lower in the affected area compared to the nationwide population (p<0.05).
Conclusion: Interest, sense of knowledge and emotions of the population are different in the affected area during the early phase of bird flu outbreak compared with the general population in the same country. Authorities must consider these differences while planning the strategy of population education during the early phase of a bird flu outbreak.
Study says wild birds unlikely to bring H5N1 to Americas
A team of American and Canadian researchers based that conclusion on a study of 248 complete avian flu viruses and several thousand gene segments of flu viruses collected from birds in Alberta and on the New Jersey coast from 2001 through 2006.
Their report, with Scott Krauss of St. Jude Children's Research Hospital in Memphis as lead author, was published this week by PLoS Pathogens. The senior author is leading flu researcher Dr. Robert Webster, also of St. Jude.
"Genomic analysis of influenza viruses from our repository failed to provide evidence of influenza viruses with their whole genome originating from Eurasia," the report states. "However, we found occasional influenza viruses from North America with single or multiple genes that originated in Eurasia. Our interpretation is that while influenza viruses do exchange between the two hemispheres, this is a rare occurrence."
The researchers say the highly pathogenic (HP) H5N1 virus has a better chance of reaching the western hemisphere via birds moved by humans than via wild birds. Nevertheless, careful surveillance of wild birds in the Americas should continue, they add.
The possible role of migratory birds in spreading the HP H5N1 has long been debated. Thousands of migratory birds died of H5N1 disease in 2005 at the Qinghai Lake wildlife sanctuary in China, a major gathering place for migratory birds, and that outbreak is suspected to have played a role in the subsequent spread of the virus to central Asia, the Middle East, Europe, and Africa.
Scientists at a United Nations Food and Agriculture Organization (FAO) conference last year in Rome agreed that wild birds played some part in spreading the H5N1 virus for long distances. But the FAO said the experts couldn't agree on exactly how the virus had reached more than 50 countries on three continents or whether wild birds provide a permanent reservoir for the virus.
A US testing program for HP H5N1 in wild birds over the past two years has revealed no signs of the virus so far. About 109,000 birds were tested from April 2006 through March of this year, according to previous reports from the US Department of Agriculture and the Department of the Interior. A low-pathogenic North American strain of H5N1 virus has been found in a few birds in the United States. Canadian surveys in 2006 and 2007 have found no highly pathogenic viruses either.
The St. Jude research team sought to investigate why the HP H5N1 virus has not reached the Americas even though the migratory paths of wild birds from both hemispheres overlap in places like Alaska. The report says genetic studies of flu viruses from wild birds have shown they generally fall into two "superfamilies" American and Eurasian which implies that the transfer of whole viruses between the eastern and western hemispheres is infrequent. The study included collection of cloacal and blood samples from wild ducks in Alberta and of fecal samples from shorebirds (including gulls) on Delaware Bay in New Jersey. Surveillance of wild birds in the two areas had been ongoing since 1976 and 1985, respectively.
The researchers found influenza A viruses in 98 (16.6%) of 590 cloacal samples from the ducks and in 114 (5.8%) of 1,970 samples from shorebirds. Fourteen of the 16 known hemagglutinin (H) subtypes were represented (H1-H13, H16), as were all nine of the neuraminidase (N) subtypes. The most common subtypes in ducks were H4N6, H1N4, and H10N7, while the most common in shorebirds were H10N7, H1N9, and H7N3. No H5N1 subtypes were found. In addition, serologic studies of blood samples gathered from about 700 Alberta ducks in 2004, 2005, and 2006 revealed no evidence of HP H5N1 infection. The findings also included 27 H7 viruses, 24 of which were H7N3, collected from the shorebirds in 2006. Testing in chickens showed the H7N3 viruses were nonpathogenic unlike the H7N3 strain that caused a poultry outbreak in British Columbia in 2004 but the viruses replicated in the chickens were lethal to chicken embryos.
In their genetic analysis, the authors examined 6,767 gene segments (which had been described in an earlier study by a St. Jude team) and 248 complete genomes. They found a low rate of "outsider events" gene segments belonging to one superfamily (Eurasian or American) occurring in viruses from the other superfamily. Overall, 56 (0.83%) of the 6,767 gene segments analyzed were classified as "outsiders," and none of the 248 complete genomes represented a transfer from one superfamily to the other.
"Based on these studies, it is more likely that the Asian H5N1 viruses will be imported into the Americas with birds moved legally or illegally by humans," the article states.
Surveillance of migratory waterfowl has shown that many species can be infected with the deadly H5N1 virus, but there is no evidence that they become long-term carriers that "perpetuate" it, the researchers say. Instead, they write, evidence indicates that domestic ducks and geese often carry the virus despite apparent health, and in the cooler months the virus "spills over" into other poultry and migratory birds. The authors conclude that the results of their genetic studies and the lack of evidence for H5N1 perpetuation in wild birds "make the probability of introduction of HP H5N1 into the Americas by migratory birds an unlikely event."
Other wildlife-disease experts who were not involved in the study voiced general agreement with the findings and conclusions. David E. Stallknecht of the University of Georgia in Athens, said the findings agree with previous research on the risk of HP H5N1 reaching the Americas via wild birds.
"These [previous] results probably provided the best evidence that the probability of HPAI (HP avian influenza) H5N1 moving to North American via wild birds was slim at best." In view of the other research results, including the failure to find HP H5N1 in more than 400,000 healthy wild birds tested to date and field evidence from outbreaks in Europe, Stallknecht said, "I certainly agree with the conclusion presented in this manuscript."
Dr. Patrick Redig, associate professor in the College of Veterinary Medicine and director of the Raptor Center at the University of Minnesota in St. Paul, called the report by Krauss and colleagues "a very important paper." Because it is based on surveillance that goes back a number of years, it "provides historical evidence about various influenza viruses that predates all the buzz about H5N1," and it corroborates the recent large-scale testing of wild birds by the Canadian and US governments, he said. "It clearly establishes that the likelihood of the entire HP H5N1 virus being introduced into the Americas by wild waterfowl or shorebirds would be an extremely unlikely event, given the historical patterns of transfer," Redig added.
He said the study leaves open the possibility that pieces of H5N1 genetic material could turn up in viruses in the North American superfamily, "but again it would be a rare event." On the other hand, Redig said, "I think the paper does underplay the survival of the HP H5N1 in wild birds, given the continuing movement and introduction of the virus into various areas in Europe, particularly the latest outbreak in Suffolk, UK, and another in Saudi Arabia. While it remains to be seen if either of these can be tracked back to wild birds, there is a suggestion that the probability is not zero."
David A. Halvorson, an avian flu expert at the University of Minnesota in St. Paul, said, "This research reinforces what has been published before, that New World and Old World avian influenza viruses are distinct lineages with only occasional introduction of old world AI virus genes into new world AI viruses," he said.
Original article: Krauss S, Obert CA, Franks J, et al. Influenza in migratory birds and evidence of limited intercontinental virus exchange. PLoS Pathogens 2007 Nov;3(11). (CIDRAP 11.16.07
APEC Center for Technology Foresight: Technology Roadmapping Workshop
The APEC second technology roadmapping workshop, "Converging Technologies to Combat Emerging Infectious Diseases", held in Chinese Taipei (as a part of APEC-wide project) was recently completed with success. The final stage of this project are now being planned. The final symposium, which aims to discuss longer term perspective to enhance the regions capacity in development and utilization converging technologies that contribute to the successful prevention and management of emerging infectious diseases. The details can be found in the following links:
Ponpiboon Satangput, Ph.D., Policy Researcher, APEC Center for Technology Foresight
A Description of the Process of Seasonal and H5N1 Influenza Vaccine Virus Selection and Development (WHO)
Introduction: Influenza vaccine is the best available protection against the disease. Among all vaccines, however, the process of making influenza vaccines is considered uniquely complicated and difficult. One reason is that the constantly evolving nature of influenza viruses requires continuous global monitoring and frequent reformulation of the vaccine strains. Another reason is that the rapid spread of these viruses during seasonal epidemics, as well as the occasional pandemic, means that each step in the vaccine process must be completed within very tight time frames if vaccine is to be manufactured and delivered in time. In response to the realities imposed by influenza, a highly functional process has evolved over decades in which the public and private sectors work together to develop and produce influenza vaccine. This paper, and the accompanying Diagram, describe many aspects of the influenza vaccine process including important similarities and differences in how seasonal human influenza viruses and H5N1 viruses are handled.