Flu Scan for Jun 25, 2015

H5N2 recess lengthens
;
H5N1 cases in Egypt
;
H3N2 mismatch mutation

Respite from H5N2 outbreaks continues for Minnesota, Iowa

The predicted summer break in H5N2 avian influenza activity is growing longer in hard-hit Minnesota and Iowa, allowing more areas to be released from quarantine and more poultry farms to restock their barns.

Minnesota has now gone 20 days with no new outbreaks, while Iowa has gone 9 days. Several weeks ago, animal health officials predicted that the outbreaks would fade with warmer summer weather and increased sunshine, conditions less favorable for the virus.

In a weekly update today, the Minnesota Board of Animal Health (MBAH) said seven farms in five counties (Kandiyohi, Meeker, Ottertail, Pope, and Stearns) have now been cleared to restock with poultry. Several other farms plan to restock next week.

In addition, uninfected farms in control zones around outbreak farms in nine counties have been released from quarantine, meaning they can move birds again, according to the MBAH. Six control areas have been released in the past week—four in Stearns County and one each in Lyon and Watonwan counties.

Minnesota has had outbreaks on 108 farms in 23 counties, while Iowa has had 77 in 18 counties.

Among other affected states, Nebraska reported its latest H5N2 outbreak Jun 16, while South Dakota's last one was reported May 28. In Wisconsin and North Dakota, the latest incidents date back to May 4 and Apr 24. None of those states have had more than 10 events.
MBAH avian flu information

 

H5N1 sickens two more in Egypt, one fatally

Egyptian authorities have reported two more human H5N1 avian flu infections, involving a 40-year-old woman in Sohag governorate who died from her illness and an individual from Faiyum governorate.

The cases were among new database listings from the United Nations Food and Agriculture Organization (FAO) that were flagged by FluTrackers, an infectious disease news message board. The FAO listings are based on reports from national authorities.

The case in Sohag appears to be the same one reported by the Egyptian media yesterday. No other details were available about the latest patient from Faiyum, other than that the observation date was Jun 13.

The two new cases increase Egypt's H5N1 total so far this year to 146 cases, according to a running list kept by FluTrackers.
Jun 24 FluTrackers thread
Jun 24 Cairo Post story
FluTrackers H5N1 in Egypt case list

 

Study: Single mutation may have led to poor H3N2 vaccine response

A single mutation in the H3N2 virus circulating this past flu season might be largely responsible for the low effectiveness of last year's flu vaccine, researchers said today in Cell Reports.

The US researchers used reverse engineering to convert the 2014-15 H3N2 vaccine strain into a panel of H3N2 strains that have hemagglutinin mutations found in currently circulating H3N2 strains. They then tested whether the viruses would be recognized by antibodies in blood cells taken from ferrets and sheep that had been exposed to the H3N2 vaccine strain.

They found that a single mutation in the F159S amino acid residue of hemagglutinin diminished antibody recognition by as much as 75% compared with antibody recognition of the unaltered H3N2 vaccine strain.

The investigators then assayed human blood samples taken before and after exposure to the 2014-15 vaccine. They found that vaccination was significantly less effective at increasing antibody recognition of the F159S-mutant strain compared with the unaltered strain.

"We find that some human immune responses are heavily focused on single regions of the flu virus and that single viral mutations can evade these immune responses," said senior author Scott E. Hensley, PhD, of the University of Pennsylvania, in a Cell Press news release. "Influenza viruses might have evolved in a way that promotes the generation of narrow immune responses that are easy to circumvent via single viral mutations."
Jun 25 Cell Rep abstract
Jun 25 Cell Press news release

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