Flu Scan for Nov 21, 2014

New Dutch avian flu outbreak
Some H3N2 mismatch
H9N2 transmission study

Avian flu detected on 3rd Dutch farm; H5N8 confirmed on 2nd

A third poultry farm in the Netherlands has been hit with avian flu, as Dutch authorities confirmed the H5N8 strain on the second affected farm, according to two separate Reuters stories today.

H5N8 was first confirmed in the country on Nov 17, on a farm in Utrecht province. Yesterday officials reported that an H5 strain had struck a farm of 43,000 chickens in the village of Ter Aar. Further testing revealed the strain to also be H5N8, one Reuters report and a Dutch report filed with the World Organization for Animal Health (OIE) said.

That strain led to costly outbreaks in South Korea earlier this year and in Germany and Britain in recent weeks.

The third outbreak is on a 10,000-chicken farm in the northern town of Kamperveen, meaning that 3 of the nation's 12 provinces have been affected, Reuters reported in a separate story. All birds on the farm will be culled to prevent disease spread, and a 6-mile exclusion zone has been established. Officials will inspect 32 nearby farms. The strain responsible is not yet known.

A total of 203,000 chickens have been or will be destroyed in the three outbreaks, the story said. About 2,000 businesses in the Netherlands house more than 100 million chickens and produce about 10 billion eggs each year.
Nov 21 Reuters story on H5N8 confirmation
Nov 21 OIE report
Nov 21 Reuters story on third affected farm

In related news, the head of the OIE said the Netherlands is susceptible to animal outbreaks such as these, according to yet another Reuters story.

"When there is a disease in the Netherlands, which is the country in the world where the concentration of farms is the highest, be it for poultry or pigs, it hurts," said Bernard Vallat, DVM, OIE director-general. "The Netherlands are really vulnerable because of this density [of farms]."
Nov 21 Reuters story quoting Vallat


Early CDC flu data show some H3N2 mismatch

US flu activity remains at low levels, but early testing on a small number of H3N2 viruses has shown a fair amount of divergence from the strain in the vaccine, the Centers for Disease Control and Prevention (CDC) noted in its weekly update today.

The agency said that 19 (56%) of 34 H3N2 viruses from patients tested match the H3N2 component of this season's flu vaccine, while 15 showed reduced titers with antiserum produced against the vaccine strain, called A/Texas/50/2012, indicating a mismatch. Among the 15, "the majority" were antigenically similar to A/Switzerland/9715293/2013, the H3N2 virus selected for the 2015 Southern Hemisphere flu vaccine.

The Swiss strain was first detected in small numbers in the United States in March "and began to circulate in greater numbers over the spring and summer," the CDC said.

Regarding flu activity, the CDC reported that the entire nation is experiencing minimal to low activity of influenza-like illness (ILI), except for Puerto Rico, which is reporting high ILI activity. Most states are reporting sporadic or local geographic spread of influenza, with a few southern states, Massachusetts, and Puerto Rico reporting regional spread.

The agency said that 9.3% of respiratory specimens tested were positive for influenza, 88% of which were influenza A. None of the 257 influenza A viruses subtyped were 2009 H1N1; they were all H3N2.

The CDC said that deaths from pneumonia and flu were below threshold levels, as were outpatient ILI visits. No new flu-related pediatric deaths were reported.
Nov 21 CDC FluView report


Study finds mammal transmission and virulence potential in H9N2

A number of H9N2 avian influenza virus subtypes have acquired mutations that allow them to transmit between and cause disease in ferrets, according to a study published yesterday in PLoS Pathogens.

Researchers at the Chinese Academy of Agricultural Sciences' Harbin Veterinary Research Institute studied receptor binding, replication, and transmission in 35 H9N2 virus strains that represent 17 genotypes. All strains were obtained from live-poultry markets in southern China between 2009 and 2013.

Six out of 9 strains were transmitted by respiratory droplets between ferrets, and 2 of these strains were highly transmissible. Infection had a variable effect on the ferrets' lungs, ranging from severe bronchopneumonia to mild lesions.

Researchers found that the H9N2 subtypes that had infected ferrets had acquired mutations that enhanced the virus' virulence and transmissibility. When mice were inoculated with H9N2, 26 strains were able to replicate and cause virulent disease.

All 35 strains preferentially bound to human-like cell receptors, and 2 strains retained their ability to bind to avian receptors, which may enhance H9N2's transmissibility. Several strains also showed evidence of a mutation that causes resistance to amantadine and rimantadine.

Although H9N2 shows low pathogenicity in poultry, the study demonstrates that the genetic variation it has accumulated in birds may have implications for potential future transmission to and between humans.
Nov 20 PLoS Pathog

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