Outside of Europe, WHO reported on 4 June that as of 30 May active but declining transmission of pandemic influenza virus continued to be reported from parts of the Caribbean and Southeast Asia. These are the parts of the world with the most pandemic activity recently though low level transmission is occurring elsewhere. In Cuba, pandemic influenza virus transmission has begun to decline after plateauing since mid-April 2010. In both Costa Rica and Columbia in the Tropical South American zone, there has been persistence of low level circulation of pandemic influenza virus since the beginning of 2010. In Asia transmission of the pandemic virus continues in Singapore and Malaysia, and to a lesser extent in Bangladesh. In Singapore, during the last week of May 2010, levels of acute respiratory infections finally fell below the local epidemic threshold and with that the proportion of respiratory samples testing positive for A(H1N1) declined to 29% from 39%. In Malaysia and Bangladesh, the numbers of new confirmed cases have been relative unchanged for the past 6 and 3 weeks, respectively, suggesting stable persistence of low level pandemic virus circulation during the past month. Pandemic transmission has now declined in West Africa.
Seasonal influenza B types viruses are currently circulating globally, although at low levels. A new finding is that during the latter part of May low but significant levels of predominantly seasonal influenza H3N2 viruses have been detected in Kenya and Tanzania. A difficult in interpreting such findings is that these are countries that previously have reported few data concerning influenza.
The pattern of influenza in the temperate countries of the Southern Hemisphere, notably the countries with well-developed surveillance systems: Australia, New Zealand and Chile, will be of particular interest to Europe in the coming months. Normally influenza illness does not start to rise until May or June in these countries. The special interest this year is because these countries will be the first to experience the second winter of transmission with the pandemic virus. Hence they will give an indication of what Europe can expect in its winter of 2010/2011 as they did for the first winter. As of the second half of May incidence of influenza like illness (ILI) activity attributable to influenza itself was low in these countries except for localized areas of pandemic influenza activity in parts of Chile. New Zealand has published on its web-site a report of a seroepidemiological study that reports that around 29% of New Zealanders were immune to the pandemic influenza virus following its first winter (by March 2010)..