Flu Scan for Apr 25, 2014

Flu season winding down
H7N9 in Taiwan

US flu season winding down with influenza B wave

Most flu markers in the United States declined last week, but the Northeast is still in the grip of a wave of influenza B activity, the US Centers for Disease Control and Prevention (CDC) said today in its latest FluView report.

The agency said it's not uncommon for a second wave of flu activity involving seasonal flu viruses other than the predominant one to occur toward the end of a season and that some disease activity could continue into May.

The 2009 H1N1 virus dominated during most of the season, but this week influenza B accounted for the largest percentage of circulating viruses, with the number of H3N2 positives increasing as well.

Though the country has been below baseline for clinic visits for flulike illness, two CDC regions, both in the Northeast, are still above their baselines. The overall percentage of respiratory specimens that tested positive for flu dropped last week from 14.5% to 12%.

One state—Texas—reported moderate-intensity flu activity, and wide geographic spread was reported by Connecticut, Massachusetts, New Jersey, New York, Rhode Island, and Guam.

Three more pediatric flu deaths were reported, pushing the season's total in that age-group to 89. Overall, deaths from flu and pneumonia were 6.3% of all deaths, well below the epidemic threshold of 7.1%.

Canada, like the United States, is seeing influenza B circulate in several regions, consistent with late-season patterns for the strain and with the overall flu activity levels expected for this time of year, according to today's update from the Public Health Agency of Canada (PHAC).

In Europe, flu activity continued an overall decline, with low-intensity activity reported by 27 countries and local or sporadic activity reported by 19 of them, according to a report today from the European Centre for Disease Prevention and Control (ECDC). Poland was the only country to report an increasing trend. Of the respiratory samples that tested positive for flu, 84% were influenza A.
Apr 25 CDC FluView report
Apr 25 PHAC FluWatch report
Apr 25 ECDC weekly flu surveillance report


Taiwan detects fourth imported H7N9 case

Taiwan today reported its second imported H7N9 influenza case this week, in a 39-year-old Taiwanese resident who had traveled to two areas of eastern China before getting sick. The illness is Taiwan's fourth imported case of H7N9.

According to a machine translation of a statement from the Taiwan Center for Disease Control and Prevention, the patient traveled to China between Mar 31 and Apr 19, visiting Beijing and the city of Kushan in Jiangsu province. That province has reported several H7N9 cases, including some recent ones. A report today from China News Agency (CNA) said the patient is a businessman.

On Apr 19, the day the man returned to Taiwan, he had fever, shortness of breath, and other symptoms, which prompted him to seek medical care. He was apparently hospitalized on Apr 23 after x-rays showed pneumonia. He was treated with antivirals, and his initial throat swab tested negative for H7N9. He was re-tested because his symptoms persisted, and those samples were reported positive for H7N9 today.

The initial investigation into the source of the man's infection found no history of exposure to poultry or poultry markets. Health officials are monitoring the man's contacts, including passengers who were on his flight back to Taiwan.

The new case brings the overall H7N9 outbreak total to 432, according to a case list kept by the FluTrackers infectious disease message board. So far 296 cases have been reported in the second wave of the outbreak, compared with 136 in the first.
Apr 25 Taiwan CDC statement (in Chinese)
Apr 25 CNA story
FluTrackers human H7N9 case count

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