Flu Scan for Mar 20, 2017

Low-path H7N9 in Alabama
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More China H7N9 cases
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US flu ebbs

Low-path H7N9 confirmed in one of Alabama's outbreaks

Alabama officials have received results on samples collected from one of the state's recently announced avian flu outbreaks, indicating low-pathogenic H7N9 detected in guinea fowl at the TaCo-Bet Trade Day flea market in Jackson County.

According to a Mar 16 statement form the Alabama Department of Agriculture and Industries (ADAI), the source of the guinea fowl, also in Jackson County, is under quarantine and continued surveillance, and the remaining birds have been culled.

Tests to confirm the subtype were conducted by the US Department of Agriculture National Veterinary Services Laboratory (NVSL) in Ames, Iowa. Testing is still under way on samples from two other outbreak locations in north Alabama, from a commercial farm in Lauderdale County and from a backyard holding in Madison County.

Alabama authorities, however, suspect that the two other outbreaks involve the low-pathogenic strain as well, because neither flock showed signs of illness. Out of an abundance of caution, the company that owns the commercial breeding farm opted to depopulate the flock, as did the owner of the backyard birds.

The low-pathogenic H7N9 finding is the second recent detection in the United States. On Mar 10, Tennessee officials announced low-pathogenic H7N9 at a farm in Giles County. Tennessee has also reported two recent highly pathogenic H7N9 outbreaks in Lincoln County. The Tennessee outbreak locations border Alabama's outbreak areas. Genetic tests so far have shown the H7N9 viruses recently detected in the United States are related to North American wild bird lineages and have no connection to the H7N9 strain sickening people and poultry in China.
Mar 16 ADAI press release
Mar 14 CIDRAP News story "Alabama officials investigate 3 avian flu detections"

 

China's fifth wave H7N9 total climbs by 21

Hong Kong's Centre for Health Protection (CHP) on Mar 17 announced in one of its regular updates that China reported 21 more H7N9 avian influenza cases, 4 of them fatal, from Mar 10 to Mar 16. The mainland continues to report a steady stream of cases in its fifth and biggest wave of H7N9 activity, which peaked in February.

Illness onsets for the latest group of patients range from Feb 28 to Mar 13. The latest cases are in seven different provinces, with about half from Guangxi and Hunan. Eighteen of the people had known exposure to poultry or poultry markets.

China has now reported at least 565 cases and 174 deaths in the fifth H7N9 wave. Hong Kong, Taiwan, and Macao have also reported cases that were imported from the mainland.
Mar 17 CHP statement

 

US flu continues to decline, but 5 new pediatric deaths reported

Indicators of US influenza activity showed elevated but declining flu activity, but five new flu-related deaths in kids were confirmed, the Centers for Disease Control and Prevention (CDC) said in its weekly update on Mar 17.

Flu was geographically widespread in 36 states for the week ending Mar 11, the CDC said, down from 39 the week before. Eleven states reported regional flu activity, up from 8 the week before.

The percentage of respiratory samples that tested positive for flu was 18.3%, down from 18.6% the week before. The proportion of outpatient visits for influenza-like illness (ILI) was 3.7% , up from 3.6% the week before and still well above the national baseline of 2.2%. Flu activity has now remained elevated for 13 straight weeks.

Last week 18 states reported high ILI activity, which was up from 14 the week before. Seven states saw moderate ILI activity, compared with 12 the week before. Seven of 10 regions noted ILI above baseline levels, compared with 8 the week before.

Another marker that rose slightly was hospitalization rate, which climbed from 43.5 lab-confirmed flu hospitalizations per 100,000 population to 46.9 per 100,000. Among those 65 and older, the rate rose from 198.8 to 214.0 per 100,000 population. In 2012-13, another season dominated by the H3N2 "A" strain, the overall hospitalization rate at this point in the season was 40.4 per 100,000 population.

Two of the pediatric deaths were caused by H3N2, one by an influenza A virus that wasn't subtyped, and two by influenza B. The deaths happened in late January through early March. The CDC reported eight pediatric deaths the week before and have now confirmed 53 flu-related deaths in that population for the season. That compares with 111 for the entire 2013-14 season, 148 in 2014-15, and 89 last season.

For the week ending Mar 11, 61.1% of flu specimens were influenza A and 38.9% were influenza B, compared with 68.6% and 31.4%, respectively, the week before. (The late-season flu B surge is typical.) Of the "A" strains that were subtyped, 97% were H3N2.
Mar 17 CDC FluView report
Mar 17 CDC summary of FluView findings

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