Avian flu hits again in Iowa and Nebraska
Iowa ended an 8-day quiet spell today with the report of a new avian influenza outbreak on a chicken farm, while Nebraska reported that the virus was found on a farm that was already being depopulated because of outbreaks at neighboring farms.
The Iowa outbreak involves an egg farm with an estimated 1 million birds in Wright County, in the north-central part of the state, the Iowa Department of Agriculture and Land Stewardship (IDALS) reported. It is the county's sixth outbreak, and the state's first since Jun 8.
Initial testing showed the presence of an H5 virus in the flock, the IDALS said. Confirmatory test results from the US Department of Agriculture's national veterinary lab in Ames, Iowa, are awaited.
Also, the IDALS said depopulation of flocks has been completed at all 76 of the previous outbreak sites, which housed 32.7 million birds total. That includes 35 turkey farms with 1.14 million birds, 35 egg and pullet farms with 31.56 million, and six backyard poultry flocks with 4,679.
Meanwhile, the Nebraska Department of Agriculture (NDA) said today that avian flu has now been confirmed on a Dixon County farm where a flock of 200,000 pullets was already being depopulated because of outbreaks at several neighboring farms.
Four other farms in the county are under the same ownership, and three of those have had avian flu outbreaks, the NDA noted. The virus has not been found on the fourth one, but the owner decided to depopulate it as a precaution.
One other Nebraska county, Knox, has a farm that is under quarantine because of a presumptive positive test close to 3 weeks ago, but further tests still have not confirmed the finding, the NDA said today. Plans call for lifting the quarantine after 21 days of negative test results. Dixon and Knox counties are both in northeastern Nebraska.
Jun 16 IDALS press release
Jun 16 NDA weekly update
Southern Hemisphere flu levels on the rise
Flu activity at the start of the Southern Hemisphere's flu season is low but is increasing in most reporting countries, the World Health Organization (WHO) said yesterday in its latest global flu update.
Flu is above the seasonal threshold in Australia, detection rates are increasing steeply in South Africa, and flu is at expected seasonal levels in South America's temperate countries, the agency said. Influenza A strains are predominant in South Africa, with all three strains circulating in Australia.
Other parts of the world seeing recent flu activity upticks include Guatemala, Vietnam, and Singapore, according to the WHO. Flu activity is decreasing in many parts of the world and is at interseasonal levels in North America.
At the global level, 51% of recently subtyped viruses have been influenza B. Of the influenza A viruses, 77.1% were the H3N2 subtype and 22.9% were the 2009 H1N1 virus.
Jun 15 WHO global flu update
Study: Rates of flu higher in younger pigs
Influenza viruses are found in about 8% of nasal samples taken from farm pigs, but the rate is markedly higher in the youngest pigs in a herd, University of Minnesota researchers reported yesterday in PLoS One.
The team visited five breeding herds in the Midwest, taking nasal swabs monthly for a year. At each visit they collected 30 swabs from each of three groups: (1) replacement females that had lived on the farm for less than 4 weeks (new gilts), (2) replacement females on the farm for more than 4 weeks (gilts), and (3) pigs less than 21 days old (piglets). They collected 4,190 swabs from 141 groups of pigs by study's end.
At least one sample tested positive for influenza A in 28 (20%) of the sampled groups using polymerase chain reaction testing. Overall, 324 (7.7%) of nasal swabs tested positive. The odds of testing positive for new gilts, however, were 7.9 times higher than for gilts, and for piglets the odds were 4.4 times higher than for gilts.
The authors conclude, "Based on these findings, we recommend that IAV control strategies be aimed at preventing infection before gilts are introduced into the farm, and in pigs prior to weaning."
Jun 15 PLoS One study