Flu activity in the United States increased slightly last week, with similar rises in other Northern Hemisphere countries and brisk activity in the Middle East, much of it driven by the 2009 H1N1 virus, which has become the predominant strain in many locations.
Flu levels rise a notch in US
The US Centers for Disease Control and Prevention (CDC) said today that the percentage of clinic visits for flulike illness last week was 2%, putting it a bit below the national baseline of 2.1%. The percentage of respiratory specimens that tested positive for flu last week was 3%, an increase from 1.8% reported the week before.
Tests at public health labs last week found that 83.9% of flu specimens were influenza A and 16.1% of them influenza B. Of the subtyped influenza A viruses, 61.7% were the 2009 H1N1 virus.
One more pediatric flu death was reported, lifting the season's total to seven. Overall deaths from flu and pneumonia in both of the CDC's surveillance systems were below their seasonal baselines. Flu hospitalization tracking is under way now, and the rate was 1.5 per 100,000 population, with the highest levels in seniors and children younger than 4.
Only Puerto Rico and South Carolina reported high flulike illness activity, a marker based on clinic visits for flu. No states reported widespread geographic spread of flu, with Guam, Puerto Rico, and nine states reporting regional spread: Arizona, California, Connecticut, Iowa, Massachusetts, New Hampshire, North Carolina, Pennsylvania, and Virginia.
Globally, 2009 H1N1 surges
At the global level, flu levels remained high in Middle East countries, including Israel, Jordan, Oman, Iran, Bahrain, and Qatar, the World Health Organization (WHO) said in its latest report, released yesterday but dated Jan 4. Many of the illnesses were caused by the 2009 H1N1 virus, but some of the countries are also reporting influenza B.
Elsewhere, flu activity is picking up in the Northern Hemisphere but is still at low levels, the WHO said. Some areas reporting increases include Northern and Eastern Europe and Mongolia.
The most recent global surveillance showed that influenza A viruses made up 89% of flu detections in late December, and of the subtyped influenza A samples, 93.3% were 2009 H1N1.
Jan 15 CDC FluView report
Jan 4 WHO global flu update