U.S. Study Defines 2 Clear Bird Flu Strains

20 March 2006 (Reuters Health)—The H5N1 strain of bird flu in humans has evolved into 2 separate strains, US researchers reported, which could complicate developing a vaccine and preventing a pandemic.

One strain, or clade, made people sick in Vietnam, Cambodia, and Thailand in 2003 and 2004, and a second strain, a cousin of the first, caused disease in people in Indonesia in 2004.

Two clades may share the same ancestor but are distinct, the team from the US Centers for Disease Control and Prevention (CDC) found.

“Back in 2003, we only had one genetically distinct population of H5N1 with the potential to cause a human pandemic. Now, we have 2,” said the CDC's Rebecca Garten, who helped conduct the study.

Speaking to the International Conference on Emerging Infectious Diseases in Atlanta, Garten said that the pool of H5N1 candidates with the potential to cause a human influenza pandemic is getting more genetically diverse, which makes studying the virus more complex and heightens the need for increased surveillance.

“As the virus continues its geographic expansion, it is also undergoing genetic diversity expansion,” Garten said in a statement.

The US Health and Human Services Department has already recognized the 2 strains and approved the development of a second H5N1 vaccine based on the second clade.

Several companies are working on H5N1 vaccines experimentally, although current formulations are not expected to protect very well, if at all, against any pandemic strain.

A vaccine against a pandemic flu strain would have to be formulated using the actual virus passing from person to person.

Low-Dose Flu Shots Could Stretch Supply: A Study

20 March 2006 (Reuters)—Five people can be protected with just 1 dose of seasonal flu vaccine, researchers said, but the development was unlikely to have an effect on the expected coming battle with bird flu.

The researchers were able to stretch the supply of vaccine by administering doses one-fifth of the normal strength, with injections under the skin instead of into muscle, the way full-strength doses are normally delivered.

“Although these results are preliminary, we found that the reduced dose administered intradermally—under the skin— was at least as effective in preventing flulike illness as the standard, intramuscular dose of the vaccine,” said Dr. Kathryn Kirkland of the Dartmouth-Hitchcock Medical Center in Lebanon, New Hampshire.

The findings were presented at a meeting of the Society of Healthcare Epidemiology of America.

Kirkland said in an interview that the finding could help alleviate shortages of seasonal vaccine, but it could not be extrapolated to a vaccine for protecting humans from bird flu, if one is developed.

She said that preliminary research has indicated that a stronger dose would be needed for bird flu than was used in the seasonal flu experiment.

Kirkland's study was prompted by the 2004 shortage of flu vaccine, when onehalf of the US supply was wiped out by contamination at 1 of 2 flu vaccine manufacturers.

The study included vaccination of 1602 healthy people with a reduced-dose vaccine. It produced results similar to those of standard doses.

Editor's comment. Unfortunately, these results seem unlikely to translate into the development of vaccines againstH5N1 avian influenza. A recent study published in the 30 March 2006 issue of the New England Journal of Medicine demonstrated that, even with very large doses of the vaccine given twice, only approximately one-half of the study population developed what are considered to be protective antibody titers. The H5 antigen may turn out to be problematic in terms of vaccine production.

Alaska to Run Bird Flu Tests in Lakes and Ponds

30 March 2006 (Yereth Rosen [Reuters Health])—Biologists in Alaska plan to test water samples from lakes and ponds in the habitats of migratory birds to check for traces of the deadly avian flu virus, state officials said.

Alaska is considered to be North America's most likely point of entry for the H5N1 strain of bird flu, because it stands at a crossroads of wild waterfowl and shorebird migration to and from Asia.

State officials plan to monitor the natural habitat of migratory birds for contamination from infected birds' droppings in addition to collecting swab specimens from nearly 15,000 wild birds spread over >2 dozen species.

“If we have birds bringing this in from Asia sit down on a water body, other species of birds that don't interact directly with Asia may also use that water body and pick up a virus,” Matt Robus, director of Alaska's Division of Wildlife Conservation, told reporters.

Mallards and pintails in the water could become infected and then carry the virus south, officials said.

Alaska's test results will be monitored carefully to see whether the H5N1 virus, like other influenza viruses, mutates to become more contagious, said Richard Mandsager, director of Alaska's Division of Public Health.

State and federal wildlife agencies have established a toll-free number for citizens to report bird die-offs or suspiciously sick birds, officials said.

There is also a bill pending in the legislature to increase the state's authority to quarantine sick domesticated animals, including backyard poultry and pet birds that might be vulnerable to the strain of avian flu.

W.H.O. Calls for Urgent Studies on Best Use of Tamiflu

17 March 2006 (Reuters)—The World Health Organization (WHO) called for urgent studies to determine optimal doses of flu drug Tamiflu to be used in the fight against human bird flu.

It reaffirmed that Tamiflu should be used to treat suspected cases and to prevent the disease in health care workers or other persons who may have been exposed to infection, but clinical trials were lacking to show any effectiveness against the deadly H5N1 virus.

“There is no direct clinical trial evidence that shows that oseltamivir is effective in human H5N1 disease, because such studies have not yet been conducted,” the WHO said in a statement posted on its Web site (http://www.who.int).

“Because the optimal dosage has not been resolved by clinical trials, and because H5N1 infections continue to have a high mortality rate, prospective studies are needed urgently to determine optimal dosing and duration of treatment for H5N1.”

The United Nations agency gave recommended doses for both treatment and prevention in adults and children 11 year old. Its recommended treatment for adults suspected to have the disease is 75 mg twice per day for 5 days.

“It is possible that severely ill patients might benefit from longer duration of therapy (e.g., 7–10 days) or perhaps higher doses (e.g., 300 mg/day), but prospective studies are required,” it said.

Children should be given the drug preventively for the same length of time in weight-adjusted doses.

“For people with repeated or prolonged exposure, such as health care workers or personnel involved in bird culls, preexposure courses, repeat postexposure courses, or continuous treatment may be necessary,” it said.

Editor's comment. From reading the literature and news reports, I would be inclined to use a dose of 150 mg twice daily for anyone ill with avian influenza (a disease with a mortality rate of 150%), as has been suggested by some.

Bangladesh Polio Case a Fresh Setback to Global Battle

16 March 2006 (Reuters)—Bangladesh has reported its first case of polio in nearly 6 years, dealing a fresh blow to a global campaign to eradicate the crippling disease, the World Health Organization (WHO) said.

A 9-year-old girl in the southern Chittagong province was paralyzed in January. Genetic sequencing has confirmed that it was the polio virus and that it was closely related to viruses detected in India, the WHO said in a statement.

This was the first case reported since August 2000 in Bangladesh, which will launch a nationwide polio immunization campaign on 16 April, it said.

The United Nations agency, which launched a worldwide campaign in 1988 to wipe out polio, failed to reach its target of halting transmission worldwide by the end of 2005.

It announced last month that Egypt and Niger were free of endemic polio, leaving only 4 countries where polio is endemic— Nigeria, India, Pakistan, and Afghanistan.

“Until polio is gone from endemic areas, we will continue to see importations to polio-free countries,”WHOspokesman Oliver Rosenbauer said.

Indonesia and Yemen were still fighting outbreaks that began last year, he added.