U.S. influenza activity passes key threshold

Seasonal influenza activity in the United States recently passed a key threshold, while several cities in Europe also reported a similar rise in the spread of the illness.

The U.S. Centers for Disease Control and Prevention reported that the percentage of respiratory specimens testing positive for the flu jumped from 7.6 percent to 10.5 percent. The 10 percent mark is typically used by health officials to measure the beginning of a flu season, according to CIDRAP News.

U.S. flu activity may seem to have appeared late in the year, but the CDC reported that specimens testing positive for the flu did not pass the 10 percent mark until after January 15 or later in almost half of the last 30 years.

The European Center for Disease Prevention and Control recently announced that flu activity has continued to rise across the continent, but with no clear geographic progression. Belgium, Italy and Spain reported widespread flu activity. According to the ECDC, the H3N2 virus remains dominant, but there are low levels of influenza B and 2009 H1N1 as well, CIDRAP News reports.

The 2009 H1N1 virus has been dominant throughout Mexico's flu season. The Pan American Health Organization announced that Mexico has reported 2,815 influenza infections and 58 deaths. Approximately 90 percent of the cases are due to the 2009 H1N1 virus. The Federal District and Oaxaca have reported the most activity.