Jun 17, 2011 (CIDRAP News) – With the Southern Hemisphere entering its flu season, the only country to see a dramatic activity spike so far is South Africa, where the 2009 H1N1 virus is dominating and has been linked to an increase in severe infections, the World Health Organization (WHO) said today.
The flu season is over in Northern Hemisphere countries and is circulating locally in some tropical locations, such as Ghana and Togo, the WHO reported in a surveillance update.
Australia is reporting that the level of doctor's visits for flu-like illness is stable and is below levels seen for this time of year in 2008 and 2010. Though that statistic is also below the seasonal threshold in New Zealand, one Northland district has exceeded its baseline. So far influenza B is the most common virus circulating in New Zealand, although numbers are small, the WHO said.
Australia's health ministry, in its most recent surveillance report, said that, in spite of low overall flu levels, South Australia recently reported an increase in flu activity, most of it influenza B. Queensland state has recorded the country's highest number of flu infections so far this year. Most virus detections have been the 2009 H1N1 virus, though H3N2 and influenza B are cocirculating.
Some South American countries are reporting low flu activity, limited to localized transmission. For example, Brazil is reporting low levels of influenza B and H3N2 circulation, and Bolivia and Colombia are reporting a slight increase in flu activity—H3N2 in Bolivia and 2009 H1N1 in Colombia.
Colombia has reported an increase in intensive care admissions for severe respiratory infections, but most of the patients are children under age 5, and the respiratory syncytial virus has been in wide circulation in recent weeks, the WHO noted.
In African countries, flu viruses circulating locally show a mixed picture, with Ghana reporting mostly the 2009 H1N1 virus and Togo reporting mainly influenza B. Nigeria and Cameroon are also reporting modest numbers of influenza B viruses.
Tropical Asian countries are reporting low flu activity, with influenza B dominant in locations such as southern China, India, and Cambodia. However, the 2009 H1N1 virus is more common in Vietnam, where about 10% of patients with flu-like illnesses are testing positive for flu.
The US Centers for Disease Control and Prevention (CDC), in a brief update released today for the week ending Jun 11, said that although the percentage of respiratory samples positive for influenza is extremely low at 0.32%, the percentage of deaths from flu and pneumonia crept slightly above the epidemic threshold of 7%—to 7.2%.
Two more pediatric flu deaths were reported, raising the total for the season to 108. Both of the deaths were linked to the 2009 H1N1 virus.
Jun 17 WHO global flu update
Australian flu report for the week ending May 27
Jun 17 CDC flu surveillance update