3.8 million hens killed in Iowa
HARRIS, Iowa––Workers at Sunrise Farms near Harris in Osceola County, northeastern Iowa, on April 22, 2015 scrambled to kill 3.8 million laying hens to try to quell a fast-spreading pandemic of the highly pathogenic H5N2 avian influenza that started in British Columbia, Canada, in December 2014.
The National Veterinary Services Laboratories in Ames, Iowa confirmed the Sunrise Farms outbreak on April 21, 2015, a week after 27,000 turkeys were killed to contain the first known H5N2 outbreak in Iowa on a farm in Buena Vista County.
The number of hens to be killed at Sunrise Farms was reduced from 5.3 million cited in earlier media statements, apparently because not all of the barns at Sunrise Farms were full when the H5N2 bird flu was discovered.
But more than 5.3 million birds total have been killed in H5N2 control efforts in the U.S. and Canada between December 2014 and late April 2015.
Hit turkeys first
Sunrise Farms is a division of Sonstegard Foods Co., of Sioux Falls, South Dakota. The USDA on April 9, 2015 reported finding H5N2 among 34,000 turkeys on a farm in Kingsburg County, South Dakota, days after the North Dakota State University Veterinary Diagnostic discovered an avian flu believed to be H5N2 among a flock of 40,000 turkeys in Dickey County.
Simultaneous with confirmation of the Sunrise Farms outbreak, the USDA Animal & Plant Health Inspection Service on April 21, 2015 confirmed that H5N2 had been found in a backyard flock of 33 mixed birds in Juneau County, Wisconsin.
Wisconsin, the seventh state known to have been hit by the outbreak, had already been fighting H5N2 since April 13, 2015, when tests confirmed that H5N2 had killed 20,000 of a flock of 200,000 chickens at a farm in Jefferson County. The remaining chickens were killed to try to control the disease.
The Jefferson County case marked the first H5N2 outbreak among a commercially raised chicken flock in the U.S., but more than 1.2 million turkeys from commercial flocks had already died of H5N2 or had been culled in control efforts, including 900,000 in Minnesota. The Minnesota Turkey Growers Association put the dollar loss to producers at $15.7 million.
Spread as far east as Ontario
H5N2 had already been reported in Canada as far east as Ontario, the Canadian Food Inspection Agency confirmed on April 8, 2015. The first Ontario outbreak was on a turkey farm. The second, confirmed on April 17, 2015, occurred on a facility in Oxford County that breeds chickens for meat.
More than 40 H5N2 outbreaks have been reported thus far in 2015 on farms along the Pacific, Central, and Mississippi flyways, the major routes used by waterfowl migrating between winter feeding areas and the Arctic, where the birds nest each summer.
Waterfowl from around the world spend each summer in close proximity in the Arctic, but spread out to all parts of the world on their southern migrations. H5N2 is an avian flu strain known to have originated in Asia.
However, wild birds are not believed to have introduced H5N2 directly to commercial flocks, who in the U.S. and Canada spend their lives entirely indoors, sheltered from any direct contact with wild birds or wild bird effluent.
Moreover, the 2015 H5N2 outbreaks in the U.S. and Canada are occurring not when infected birds might be flying south, but rather when migratory birds are flying north, after months out of contact with related species native to other continents.
Gamecocks & geese
The intermediary vectors are likely to include gamecocks kept for fighting, ornamental waterfowl, non-migratory Canada geese, and backyard poultry kept for meat and eggs by non-commercial producers.
Among the few “wild” birds who have tested positive for H5N2 in recent weeks were a goose from the Cheyenne, Wyoming area and a gyrfalcon from Columbia Falls, Montana who was among about 50 birds kept by a falconer.
H5N2 and other avian influenzas pass easily from outdoor flocks to indoor commercial poultry barns via workers’ contaminated boots and clothing. For example, a worker who attends a weekend cockfight could infect a poultry barn just by doing his job on Monday morning.
Mutant cousin of H5N1
H5N2 is not known to infect humans, but rapidly kills birds, and is a mutant cousin of the H5N1 avian flu.
First detected in Hong Kong in 1996, H5N1 avian flu has now killed more than 400 people in 16 nations, chiefly in Indonesia, Egypt, Vietnam, and China: about 55% of all people known to have become infected.
The first North American H5N1 fatality died in Alberta, Canada, in January 2013, a month after traveling in China. At the time, any H5N1 cases occurring in North America were presumed to have resulted from foreign exposure.
That assumption can no longer be made. H5N1 has so far in 2015 turned up among wild birds and backyard flocks in British Columbia, Washington, Idaho, and Oregon.
As H5N2 and the threat of H5N1 spread, pressure is likely to increase from the agribusiness and public health sectors to try to eliminate the vector by more tightly controlling or even eliminating outdoor poultry rearing. Pressure on public agencies to exterminate non-migratory Canada geese is also likely to intensify.
In Taiwan, where at least 476 outbreaks of H5N2 have been reported since January 2015, legislation has been reportedly promised which would require that all poultry be kept indoors, if kept to produce eggs or for human consumption.