Flu activity stuck in low gear in most countries

Dec 2, 2011 (CIDRAP News) – Local or regional influenza outbreaks in a handful of countries were the only exceptions to a global pattern of low flu activity in recent weeks, the World Health Organization (WHO) said in its biweekly flu update today.

Flu activity is low overall in the Northern Hemisphere, according to the update, which covers Nov 6 through 19. That holds true for the United States, the US Centers for Disease Control and Prevention (CDC) said in its weekly update today.

In Europe the only country with localized flu outbreaks was the Netherlands, which reported influenza A/H3N2 and B cases, the WHO said. In Asia, Cambodia continued to deal with regional flu activity involving 2009 pandemic H1N1 (pH1N1) and B viruses, but cases were scarce elsewhere.

Central America likewise reported little flu, with the exception of Nicaragua, which continued to have outbreaks of pH1N1 and H3N2 viruses, the WHO reported.

In the Southern Hemisphere, the relative hot spot was Cameroon, which continued to see local outbreaks of pH1N1, H3N2, and B strains, the agency said. Elsewhere in the hemisphere, activity was limited to sporadic cases.

The WHO said 80 countries and territories reported that a total of 1,056 specimens tested positive for flu during the 2 weeks. About 58% of these were influenza A and 42% were type B. Of the A isolates, 31.4% were pH1N1 and 68.6% were H3N2.

In the United States, most flu indicators remained below baseline levels, according to today's CDC report. The weekly FluView report covers the week that ended Nov 26.

Of 2,130 respiratory specimens submitted to collaborating labs, 40 (1.9%) tested positive for flu. That percentage was up from 1.0% and 1.2% for the previous week and the week before that, respectively.

The proportion of doctor's visits for flu-like illness was 1.4%, up from 1.3% the week before but still well below the national baseline of 2.4%. Two new flu-related pediatric deaths were reported, but they were from the 2010-11 season, bringing last season's total to 120.

Also, 6.4% of all deaths reported through the 122-Cities Mortality Reporting System were due to pneumonia and influenza, still below the epidemic threshold of 7.1% for this time of year but up from 6.0% the week before.

The CDC has antigenically typed 21 flu viruses submitted to US labs beginning in October: 16 H3N2, 4 influenza B, and 1 pH1N1.

Local flu activity was reported in one state—Massachusetts. The District of Columbia, Guam, and 28 states reported sporadic flu activity, which was up by two states from the previous week. The US Virgin Islands and 21 states reported no flu activity.

See also:

Dec 2 WHO flu update

Dec 2 CDC FluView report

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