Asian Poultry Could Be Vaccinated to Contain Flu

ROME, Italy, February 6, 2004 (ENS) - A targeted vaccination campaign for poultry at risk of being infected by the highly pathogenic H5N1 avian influenza virus may be required in heavily affected countries to control the further spread of the epidemic, said global animal and human health experts gathered for emergency talks at the UN Food and Agriculture Organization (FAO).

Millions of chickens and ducks across 10 Asian countries have either died of the disease or been culled, killed to prevent its spread.

Humans have also fallen victim to the virulent bird flu. Fifteen people in Vietnam have been infected. Of these, 11 have died, two remain hospitalized, and two have recovered.

In Thailand, the Ministry of Public Health has confirmed the country's fifth human case of H5N1 virus infection. All five people have died.

Issuing a series of recommendations Thursday after two days of discussions, the experts, including representatives from the World Animal Health Organization (OIE) and the World Health Organization (WHO), said vaccinating animals could be one method along with culling and other priority measures to contain the spread of the virus.

"We are confident that with broad international and regional collaboration in support of national efforts and using all available intervention tools, the crisis can be overcome and the risk to human health be minimized," said Joseph Domenech, chief of the FAO's Animal Health Service.

Testing for its protective effect, U.S. veterinarian David Swayne will inoculate chickens with virus extracted from this breeder stock vial. (Photo courtesy USDA)

The mass culling of flocks outside of infected sites in reaction to outbreaks might be avoided and major damage to the livelihoods of rural households and national economies averted if vaccinations are carried out.

But vaccination alone will not do enough to bring the present outbreaks in poultry under control, they said.

"Culling infected flocks remains the recommended response when the disease is detected," Domenech said, adding, "Vaccination, when used together with other control measures, such as market and movement management, and good agricultural practices, offers a suitable means to support the suppression of the further spread of the virus."

"Controlling the outbreak at its source, through the safe elimination of infected flocks supported by vaccination where required, would minimize the risk to human health," said WHO's François Meslin.

Experts present at the talks agreed that such targeted vaccination would help prevent animals falling ill and reduce the amount of virus present in the environment, the so-called "viral load."

Minimizing viral load will reduce the potential of avian influenza spreading to humans, if accompanied by strict control measures such as surveillance, elimination of infected birds, animal movement control and observation of basic hygiene in animal production.

Experts agreed that the vaccination plan, using a vaccine that meets OIE's international quality standards, should be accompanied by clear monitoring and surveillance of the rapidly changing situation.

Joseph Domenech heads the Animal Health Service of the UN Food and Agriculture Organization. (Photo courtesy FAO)

The group of experts emphasized the importance of protecting people directly in contact with infected or suspected birds to reduce opportunities for the simultaneous infection of humans with H5N1 and human strains of influenza virus.

Such dual infections give the avian and human viruses opportunities to exchange genes, possibly resulting in the emergence of a new flu virus subtype that could spread by human-to-human transmission.

The health experts recommended that poultry workers, who can experience intensive exposures, be given the existing seasonal influenza vaccine. The vaccine protects against infection with currently circulating human influenza viruses, but does not protect against H5N1 infection.

They highlighted the need for substantial international financial support to fund the intensified control measures required, including personal protective equipment, and the creation of country-specific guidelines and regional coordination programmes.

"These measures will not only help deal with the immediate crisis but will also lay the ground for capacity building programs for national veterinary administrations," said Bernard Vallat, Director-General of the OIE. "Priorities will be on surveillance and monitoring of animal diseases; these measures will also help to rebuild the damaged export markets in the region."