H5N2 strikes second turkey farm in Minnesota

The highly pathogenic avian influenza (HPAI) virus H5N2 has struck a turkey farm in southwestern Minnesota, the US Department of Agriculture (USDA) announced today, marking the second H5N2 outbreak reported in the state this month.

The virus was found on a farm housing 66,000 turkeys in Lac Qui Parle County, which is about two counties to the southwest of the previous outbreak in Pope County.

Samples from the flock were tested after increased deaths were noted, the USDA said. Testing was done by the University of Minnesota Veterinary Diagnostic Laboratory, and the results were confirmed by the APHIS National Veterinary Services Laboratories in Ames, Iowa.

State officials quarantined the farm and will destroy the turkeys to prevent further spread of the virus, the USDA said, adding that none of the turkeys will enter the food system. Federal and state officials are working on additional surveillance and testing in the nearby area, the agency said.

The Minnesota Department of Health is working with poultry workers at the affected farm to ensure that they are taking the proper precautions, the statement said. No human infections with this H5N2 strain have been reported.

Earlier this month, the H5N2 virus struck not only the other Minnesota farm but also two turkey farms in Missouri and one in Arkansas, as well as a backyard poultry flock in northeastern Kansas. The virus is a relative of the HPAI H5N8 virus that originated in Asia and reached the United States late last year. Minnesota, Missouri, and Arkansas all lie within the Mississippi migratory bird flyway.

The USDA said it would inform the World Organization for Animal Health (OIE) as well as international trading partners of the outbreak.
Mar 27 USDA statement
Mar 6 CIDRAP News story on earlier Minnesota outbreak

Dutch study supports common origin for H5N8 viruses on 3 continents

An analysis of H5N8 avian flu viruses recovered from two wild ducks in the Netherlands, coupled with a review of other genetic and bird-migration data, supports the view that recent H5N8 viruses found in Europe, Asia, and North America have a common origin and have spread via wild birds, according to a report by Dutch researchers in yesterday's Eurosurveillance.

Highly pathogenic H5N8 viruses were first detected in live-bird markets in China in 2010, and the strain cropped up in South Korea and Japan early in 2014, the report says. In November it sparked outbreaks in Europe, and in December it reached the United States, where it has been detected in a number of wild birds and backyard poultry flocks.

After H5N8 was found on a Dutch chicken farm on Nov 14, 2014, researchers tested samples from 4,018 wild birds of 25 species. The team found the H5N8 virus in two Eurasian wigeons, a species that migrates long distances. They note that H5N8 infections last only a short time, which means that many wild birds must be sampled to detect the virus.

The authors sequenced the virus's complete genome and compared some sequences with those of other highly pathogenic H5 viruses found in 2014 and those of Chinese H5N8 viruses found before 2014.

"The H5N8 viruses isolated from wild birds in the Netherlands were genetically closely related to and had the same gene constellation as H5N8 viruses detected elsewhere in Europe, in Asia and in North America, suggesting a common origin," the researchers state.

Further, they write that recoveries of bird bands (rings) from "migratory duck species from which H5N8 viruses have been isolated provide evidence for indirect migratory connections between East Asia and western Europe and between East Asia and North America."

"To understand the role of wild birds in the epidemiology of H5N8 virus, sampling activities need to aim at detection of both the virus and specific antibodies with an emphasis on migrating birds in north-east Europe, Russia, and north China," they conclude.
Mar 26 Eurosurveillance report

US flu elevated for 18th straight week

The extended US flu season continues, with last week marking the 18th consecutive week of elevated influenza activity, the Centers for Disease Control and Prevention (CDC) reported today, adding that 9 new pediatric flu-related deaths occurred, bringing the season total to 116.

In addition, flu-related hospitalizations in the elderly again reached an all-time high.

Flu activity overall, however, showed more signs of declining, consistent with recent weeks. Last week the proportion of people seeing a healthcare provider for influenza-like illness (ILI) dropped from 2.3% to 2.2% but remains above the national baseline of 2.0% for the 18th consecutive week. In the past 13 flu seasons ILI has remained at or above baseline levels for 1 to 19 weeks, with an average of 13 weeks.

Six of 10 US regions reported ILI activity at or above region-specific baselines, compared with 8 during the previous week. Only Puerto Rico and Oklahoma had high ILI activity, down from four states and Puerto Rico the week before. Widespread flu was reported in seven states, mostly in the Northeast, the same as during the previous week.

The percent of specimens positive for influenza was 10.6%, the CDC noted, down from 11.2%. About 75% of viruses subtyped were influenza B, up from 67% the week before. A late-season flu B surge is typical. Almost all the influenza A viruses subtyped were the H3N2 strain.

Of the 9 new pediatric deaths, 4 were attributed to influenza B, 3 to H3N2, and 2 to an unspecified influenza A.

The rate of flu-related hospitalizations again climbed, from 57.1 to 58.4 per 100,000 population. And the rate in those 65 and over again hit a record high since the CDC began tracking that figure in 2005, rising to 289.7 per 100,000, up from 284.3 per 100,000.
Mar 27 CDC weekly FluView report
Mar 27 CDC flu situation update