Researchers Offer Battle Plans to Combat Avian Flu

Anti-viral drugs and quarantining infected individuals are two keys, studies report

WEDNESDAY, Aug. 3, 2005 (HealthDay News) -- Two articles in leading scientific journals outline plans for combating the possible pandemic of avian flu that is an ever-present fear among scientific experts.

The first article, appearing in the Aug. 4 issue of Nature, concluded that up to 3 million courses of anti-viral drugs, as well as a policy of quarantining people who are at risk, could do the trick in Southeast Asia, the epicenter of bird flu activity.

The second article, appearing in the Aug. 5 issue of Science, found that a multi-pronged strategy including anti-viral drugs, vaccines and quarantine, would be effective in containing an outbreak.

"We can't just wait until something happens. We need planning in advance," said Neil Ferguson, lead author of the Nature study and a professor of mathematical biology at Imperial College London. "Nobody's going to say it's guaranteed to work but the benefits are so huge. It's almost certainly worth a try because we have nothing else."

Articles like these can provide a basis for planning important aspects of an anticipated medical response to a bird flu outbreak, experts said.

"Even if you know everything about the virus and have your stockpile in place, you cannot respond if you do not have the public health infrastructure, the physical infrastructure and the people," said Dr. Maureen Lichtveld, chairwoman of environmental health sciences at Tulane University School of Public Health and Tropical Medicine, in New Orleans.

Awareness and willingness are already in place, she said, and the SARS epidemic went a long way toward solidifying international collaboration against a dangerous infectious disease.

"The big issue is whether the political willingness is robust enough to be able to put in place the infrastructure in advance of a potential pandemic, without the sword hanging over your neck," Lichtveld said.

The specter of a worldwide avian flu pandemic has loomed for years. This year, bird flu is widespread in Southeast Asia's poultry stocks and has infected a number of humans, with alarmingly high death rates. It has killed at least 51 people in Vietnam, Thailand and Cambodia over the past two years, according to published reports.

If the virus mutates and acquires the ability to jump easily from human to human, experts fear a deadly pandemic similar to the one that killed about 50 million people worldwide in 1918-1919.

According to the Nature article, "The continuing spread of H5N1 highly pathogenic avian influenza in wild and domestic poultry in Southeast Asia represents the most serious human pandemic influenza risk for decades."

The best hope, the authors stated, would be to stop an outbreak in its infancy.

The study researchers used computer modeling to simulate a scenario of flu transmission in Southeast Asia and then to evaluate the potential effectiveness of anti-flu drugs and a strategy of containment.

It might be possible to halt a pandemic at its start by using a combination of "social distancing" measures to reduce contact between people and prophylactic administration of anti-flu drugs such as oseltamivir or Tamiflu, the study said.

Much depends on how quickly cases are diagnosed, how quickly drugs are distributed and how quickly the virus spreads, the researchers said.

The model calculated that a containment policy would need to begin when the outbreak had affected no more than 40 people, with isolation and treatment of each new case taking place within two days.

"If there was enough planning, preparedness and commitment from the countries in the region, this strategy is probably feasible in practice," Ferguson said.

"It's worth a try but it is difficult. We clearly need a sizable anti-viral stockpile which can be deployed internationally. At the moment, I have reasons to be optimistic that WHO's [World Health Organization] own stockpile should increase in the relative near future to levels which might be needed," Ferguson said. "Beyond that, we would need training of teams on the ground to actually implement these policies because we will be chasing cases, detecting them as they come up."

The Science article also used a computer model to simulate an outbreak among a population of 500,000. The model was based on 2000 Thai census data and on a study of social networks in the Nang Rong District of Thailand.

A combination of strategies, including antibiotics, quarantine and vaccination of not-yet-infected individuals would be needed. In this case, the study authors predicted that 100,000 to one million courses of anti-virals would be sufficient. The anti-virals would need to be administered within 21 days of the first case. And a vaccine would be "prudent" even if it provided only moderate protection. At present, there is no effective vaccine for avian flu, although some are in development, the study noted.

According to this study, the current WHO stockpile of 120,000 courses of anti-virals would be enough to contain a pandemic if they were used within two to three weeks of first detection.

But this information is not the end of the story, said other experts.

"Modeling is a useful tool but a tool to facilitate in planning, not the total tool," Lichtveld said. "The next step is to go beyond the proposed model and see how valid it is, how realistic."

But with the publication of these studies, the planning is becoming more real.

"In the past, people have talked about pandemic containment as something of a pipe dream, as idle speculation," Ferguson said. "To be fair, this is the first research that has showed it's a real possibility. I have reason to believe that there is movement happening and, in particular, that WHO will start looking at pandemic containment as the initial plank of a pandemic response. It requires a cultural shift within some of these organizations and changing long-established international guidelines does take a little while, but I am optimistic."

However, not everyone in the scientific community is confident in our ability to respond to the threat in time. "I would say that we are most certainly concerned that [an avian flu pandemic] could happen, and that the conditions in Asia are potentially conducive," said Dr. Susan McLellan, associate professor of medicine in the infectious diseases section of Tulane School of Medicine.

"This is not, however, a new situation -- influenza experts have expected this to happen all along, eventually. Nor is this the only disease that could crop up as a pandemic," she added, noting that we were very lucky with SARS.

"The question which is more worrisome is whether we will be prepared," McLellan continued. "As discussed in the Nature article, containing a 'nascent' epidemic will depend on early case recognition and a rapid public health response with delivery of medication to affected areas. With lots more time to react, we haven't been able to manage that with AIDS, malaria, TB, or lots of other diseases for which we have the technology, but not the will."

She pointed out, "Certainly in this country, governmental spending to support a strong public health structure, including research and information systems to support control of infectious diseases in general, has been cut rather than expanded."

More information

The World Health Organization has more on avian flu.

SOURCES: Neil Ferguson, Ph.D., professor, mathematical biology, Imperial College London, England; Maureen Lichtveld, M.D., chairwoman, environmental health sciences, Tulane University School of Public Health and Tropical Medicine, New Orleans; Susan McLellan, M.D., associate professor, medicine, infectious diseases section, Tulane University School of Medicine, New Orleans; Aug. 4, 2005, Nature; Aug. 5, 2005, Science
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