To control bird flu, cull – don’t vaccinate

By Michael Fielding Although it’s more affordable, vaccinating chickens within two miles of an infected farm isn’t the best approach to the increased threat of avian influenza.

This, according to a new Danish study on the best methods to combat Highly Pathogenic Avian Influenza (HPAI), which found that culling on farms located between two-thirds of a mile and 1.8 miles from the infected farm is the best method.

The researchers reported that although preventive culling cuts the duration of the epidemic, it occurs on more farms than vaccinations would. For example, enlarging the culling radius to nearly two miles cuts the duration of the epidemic in half to 30 days – but at the expense of culling about 400 farms total (compared to vaccinating about 160 farms).

“While the assumed vaccination capacity of 20 farms/day already delays the vaccination to eight days after detecting a source farm, it is not a realistic capacity for the current vaccination method by injection,” according to the report, titled “Control of Highly Pathogenic Avian Influenza” released by the Wageningen University & Research Center in The Hague, Netherlands. “Until a more efficient way of administration is developed, emergency vaccination seems ineffective in bringing an epidemic under control.”

The news comes on the heels of an announcement by the Food and Agriculture Organization of the World Bank, which earlier this week urged heightened readiness and surveillance against a possible major resurgence of the H5N1 HPAI amid signs that a mutant strain of the deadly virus is spreading in Asia and beyond. (See “FAO warns of Avian Influenza resurgence,” on Meatingplace Aug. 31.)

The report was commissioned by the Danish Ministry of Economic Affairs, Agriculture & Innovation to provide a basis for decisions made in the event of a new HPAI epidemic.

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