Swine Flu Pandemic - 2009

The 2009 flu pandemic is a global outbreak of a new strain of influenza virus, officially named the "Novel H1N1", first identified in April 2009, and commonly called "Swine Flu." It is thought to be a mutation of four known strains of the influenza A virus, subtype H1N1: one endemic in (normally infecting) humans, one endemic in birds, and two endemic in pigs (swine). Experts assume that the Virus emerged from pigs in Asia, and was carried to North America by infected persons. There is also evidence that the new strain had been circulating among pigs in other continents for years before infecting humans.

Novel H1N1 flu cases have been reported in many countries around the world, with most of the cases being reported from the United States, Mexico, and Canada. Overall, the numbers of new cases of novel H1N1 flu in Mexico and the United States appears to be declining. However, outbreaks continue to be reported in some communities.

On June 11, 2009, the World Health Organization (WHO) raised the worldwide pandemic alert level to Phase 6 in response to the ongoing global spread of the novel influenza A (H1N1) virus. A Phase 6 alert level means that a global pandemic is underway and that there are now ongoing community level outbreaks in multiple parts of world. The Phase 6 pandemic alert level is a reflection of the spread of the virus, not the severity of illness caused by the virus.

World Health Organization (WHO) regions have reported 254206 laboratory-confirmed cases of novel influenza A (H1N1) and 2837 deaths. The laboratory-confirmed cases represent an underestimation of total cases in the world as many countries have shifted to strategies of clinical confirmation and prioritization of laboratory testing for only persons with severe illness and/or high risk conditions.

The novel influenza A (H1N1) virus is the dominant influenza virus in circulation in the United States, England, South Africa, New Zealand, Australia, Chile, Argentina and Brazil. South Africa has had a notable increase in the proportion of influenza that is novel influenza A (H1N1), and now it represents the majority of influenza in the country. Many seasonal influenza viruses from these countries have not been subtyped. Of those that have been subtyped in Australia, South Africa, and Argentina, the most common seasonal influenza virus is influenza A (H3N2).

In the southern hemisphere, most countries (represented by Chile, Argentina, New Zealand, and Australia) appear to have passed their peak of influenza activity and have either returned to baseline levels or are experiencing focal activity in later affected areas; while a few others (represented by South Africa and Bolivia) continue to experience high levels of influenza activity.

Many countries in tropical regions (represented by Central America and tropical regions of Asia), continue to see increasing or sustained high levels of influenza activity with some countries reporting moderate strains on the healthcare system. In temperate areas of the northern hemisphere (represented by North America, Europe, and Central Asia), influenza and respiratory disease activity remains low overall, with some countries experiencing localized outbreaks. In Japan, the level of influenza activity has passed the seasonal epidemic threshold, signaling a very early beginning to the annual influenza season.