WHO sees pockets of pandemic flu and more H3N2

Jun 25, 2010 (CIDRAP News) – Pandemic flu activity remained low in most parts of the world, though some areas such as Caribbean countries continued to see active transmission, with increased activity reported in a few areas, including Colombia and parts of India, the World Health Organization (WHO) said today.

After rising throughout winter and spring, levels of influenza B transmission throughout the world are decreasing, while influenza A (H3N2) viruses are increasing in some areas such as East Africa and South America, according to the WHO.

In a virological update that accompanied its weekly influenza report today, the WHO said overall, in the Northern Hemisphere, influenza B detections exceed that of influenza A. In the Southern Hemisphere, the proportion of influenza A (H3N2) is increasing, even exceeding that of pandemic H1N1.

Some states in India, such as Karala, have reported spikes in pandemic flu illnesses and deaths in the wake of monsoon rains. The WHO said today that severe illnesses and deaths in India are particularly occurring in pregnant women. Over the past few weeks Indian news outlets have reported that Karala, Maharashtra, Karnataka, and Andhra Pradesh states have been among the hardest hit. Today The Hindu, India's largest newspaper, reported that three deaths have recently been recorded in Andhra Pradesh.

In Colombia, pandemic flu levels have slightly increased after persistent but low-level circulation since late May, the WHO said. Other South American countries such as Venezuela and Bolivia are reporting recent circulation of seasonal influenza A and B viruses.

In Ghana, the proportion of respiratory samples testing positive for pandemic H1N1 increased from 16% to 23% during the first 2 weeks of June, according to the WHO report.

Other areas experiencing active pandemic virus transmission are Bangladesh, Singapore, and Malaysia.

Small numbers of seasonal H3N2 viruses are being detected across Africa, particularly in the east, the WHO said. "The most recent detections have been reported in Ghana, Kenya, and South Africa during the second week of June 2010. The persistence of H3N2 in this area over time very likely represents sustained community transmission of the virus."

Southern Hemisphere countries, which are in the early part of their flu season, are seeing only sporadic detections of the pandemic H1N1 virus, with generally low levels of other respiratory diseases. Australia and New Zealand both reported flu activity levels that are below national baselines.

Yesterday New Zealand's health ministry in its weekly flu update said flu activity remained low, but the pandemic H1N1 virus is still circulating alongside other respiratory viruses. It said the country's health advice phone line has seen a slight increase in the number of people experiencing flu-like illnesses and that general medical practices are noting that more young children are being seen for illnesses.

North American countries continue to report only sporadic detections of pandemic and seasonal flu.

Anthony Fiore, MD, a medical epidemiologist for the US Centers for Disease Control and Prevention (CDC) said yesterday in an update to CDC's vaccine advisory committee that US health officials are keeping a close eye on global reports of influenza B and H3N2. He said most recent global detections of influenza B have involved the Victoria lineage covered by both hemispheres' seasonal flu vaccines, though he added that some Yamagata lineage samples have been detected.

The WHO said today that most pandemic H1N1 viruses that it has analyzed so far are closely related to the pandemic H1N1 strain recommended for flu vaccines. It added that it has received no new reports of oseltamivir (Tamiflu) resistance.

See also:

Jun 25 WHO statement

Jun 23 WHO virological update

Jun 24 New Zealand health ministry flu update

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