WHO: Flu active in parts of tropics, Southern Hemisphere

Lisa Schnirring

Jul 30, 2010 (CIDRAP News) The World Health Organization (WHO) today said pandemic and seasonal flu activity across the globe is low, but said activity is increasing in some parts of the Southern Hemisphere, with significant action still occurring in certain tropical areas, such as India.

Influenza activity in the Southern Hemisphere, which is in the midst of its regular flu season, is variable, the WHO said. Flu transmission appears to have recently peaked in South Africa, where most of the circulating strains were influenza A (H3N2) and influenza B viruses. The WHO said early reports suggest South Africa has had a clinically mild flu season.

In Australia and New Zealand the pace of flu detections has been steadily increasing over the past few weeks, the WHO said. Yesterday Australia's Department of Health and Aging, in its latest flu surveillance report for the week ending Jul 16, said levels of flulike illnesses are increasing according to some surveillance systems and that 5% of lab tests are positive for influenza, about two-thirds of it pandemic H1N1 and a third of it H3N2. However, two of Australia's states reported that the most common respiratory virus was respiratory syncytial virus, and one reported it was picornavirus.

During the most recent surveillance week, Australia reported 17 new pandemic H1N1 cases from four states and four hospitalizations for flu, three of them for pandemic virus infections.

New Zealand's health ministry also issued a new flu surveillance report yesterday showing that flu activity is starting to increase significantly, especially on the northern half of the North Island, where the increase was marked. However, doctor visits for flulike illnesses were still below the country's seasonal baseline. Of the viruses subtyped, pandemic H1N1 virus is the dominant strain in New Zealand. The country's health ministry added that over the previous week 59 more people had been hospitalized for flulike illnesses.

The most active area of pandemic virus transmission in Asia is occurring in western and southern India, where the country's health officials have attributed the fresh outbreak to monsoon rains, the WHO said. Dr A.C. Mishra, director of India's National Institute of Virology, said today that the infection rate in the second pandemic H1N1 wave currently under way in the country is likely to be higher than the first wave, the Times of India reported.

He predicted the virus would spread to areas where few people have previously been infected and said the severity of the second wave so far appears similar to the first. Mishra told the Times that the virus circulating in India is still susceptible to oseltamivir and doesn't appear to have changed much.

In Southeast Asia, the pandemic virus is still circulating at low levels in a few countries, including Cambodia, Singapore, and Malaysia, the WHO said, adding that significant levels of H3N2 are circulating in Singapore.

Elsewhere in Asia, Hong Kong's Center for Health Protection said yesterday that seasonal flu levels are rising, with the pandemic virus accounting for 40% and H3N2 and influenza B each accounting for 30%, according to a statement. Officials said seven outbreaks occurred during the week ending Jul 24, half of them in nursing homes.

In tropical regions of the Americas, the WHO notes variable influenza activity, with H3N2 as the dominant strain in Panama and Nicaragua, influenza B viruses in El Salvador and Bolivia, and pandemic H1N1 in Colombia and Costa Rica.

The WHO said in a separate report that accompanied the surveillance update that it has received no new reports of oseltamivir (Tamiflu)-resistant pandemic H1N1 influenza.