level of swine influenza pandemic alert raised from phase 3 to phase 4

Human cases of swine influenza A/H1N1 virus infection also have been confirmed internationally: US has reported 40, Canada has reported 6 confirmed human cases of infection; Spain has reported 1 case; Scotland has reported 2 cases. Mexico has reported 26 cases of infection, including 7 deaths.

On the advice of the Emergency Committee of the World Health Organization, the Director-General has raised the level of influenza pandemic alert from phase 3 to phase 4. The change to a higher phase of pandemic alert indicates that the likelihood of a pandemic has increased, but not that a pandemic is inevitable.

The Emergency Committee's recommendation is based on the available data on confirmed outbreaks of A/H1N1 swine influenza in the United States, Mexico, and Canada. The Committee also considered reports of possible spread to additional countries.

The decision was based primarily on epidemiological data demonstrating human-to-human transmission and the ability of the virus to cause community-level outbreaks.

Given the widespread presence of the virus, the Director-General considered that containment of the outbreak is not feasible. The current focus should be on mitigation measures.

In Mexico, the suspected number of cases is reportedly as high as 1,600, and the suspected number of deaths in Mexico is up to 80. Potential new cases also have been reported in France, Hong Kong, and New Zealand. These numbers and reports are not yet confirmed.

Laboratory testing has found the swine influenza A/H1N1 virus is susceptible to the prescription antiviral drugs oseltamivir and zanamivir.