UN links ducks, people, rice paddies for bird flu

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UN links ducks, people, rice paddies for bird flu Mar 26,

ROME (AFP) - Concentrations of ducks, rice paddies and people are

primarily responsible for outbreaks of potentially deadly bird flu

across Asia, the UN Food and Agriculture Organisation said Wednesday.

" Rather than chickens, (these) are the major factors behind outbreaks

of H5N1 highly pathogenic avian influenza in Thailand and Vietnam, and

are probably behind outbreak persistence in other countries of the

region such as Cambodia and Laos, " said a report by the Rome-based agency.

It said a group of experts had studied a series of outbreaks between

early 2004 and late 2005 under senior FAO veterinary officer Jan

Slingenbergh, publishing its findings in the latest issue of the

Proceedings of the National Academy of Sciences of the United States.

" We now know much better where and when to expect H5N1 flare-ups, "

Slingenbergh said.

" With virus persistence becoming increasingly confined to areas with

intensive rice-duck agriculture in eastern and southeastern Asia,

evolution of the H5N1 virus may become easier to predict. "

By comparing satellite mapping of rice paddies, to show the

concentration of ducks feeding on leftover grains in harvested fields,

to outbreak timelines, the researchers were able to draw a link and

pinpoint periods when the risk of the virus spreading is at its greatest.

The role played by people comes in terms of population density, with

people numbers influencing duck movement.

" In Thailand, for example, the proportion of young ducks in flocks was

found to peak in September-October, " the report said.

" These rapidly growing young ducks can therefore benefit from the peak

of the rice harvest in November-December. "

It added: " Meat ducks are slaughtered around the Chinese New Year (in

January or February, depending on the year), a time when the volume of

sales-related duck movement rises considerably. "

Ninety percent of the world's 1.044 billion domestic ducks are in

Asia, with 775 million of them, or about 75 percent, in China and Vietnam.

In 2005, Thailand introduced the need for animal health certificates

for duck farmers, along with subsidies for indoor keeping of the

birds, feeds and enclosure building.

" Together, these measures stopped the H5N1 transmission cycle and

since late 2005, Thailand has suffered only sporadic outbreaks, " the

report noted.

Slingenbergh added that indiscriminate mass vaccination -- which the

authors found had little long-term effect in Vietnam, for example --

should be replaced by such targeted disease control measures working

off local rice-duck calendars and known hotspots.

http://news./s/afp/20080326/hl_afp/healthfluunfao_080326153240