Influenza update

Influenza update

Influenza activity in the northern hemisphere temperate zones remained at interseasonal levels. The United States of America reported 14 cases of human infection with influenza AH3N2v so far this year, since the first case in June.

In most regions of tropical Asia influenza activity decreased, except for Cambodia, India and Viet Nam where there are some signs of increasing influenza A activity. In Central America and the Caribbean regions, influenza activity continued to increase in Costa Rica, El Salvador and Nicaragua, remained high in Cuba, and decreased in the Dominican Republic. In tropical South America, influenza AH1N1pmd09 became the predominant circulating virus in most countries, except in Ecuador where respiratory syncytial virus RSV remained the most commonly detected respiratory virus.

Influenza transmission has peaked in the southern cone of South America and in South Africa in late June. In all of those areas, transmission was primarily associated with influenza AH1N1pdm09. In Australia and New Zealand, numbers of influenza viruses detected and rates of influenzalike illness have been lower than in previous years, but have not yet definitively peaked. Influenza AH3N2 and type B have been much more commonly detected than AH1N1pdm09 in both of those countries.