Swine Flu

The 2009 outbreak of Influenza A virus subtype H1N1 is an epidemic of a new strain of influenza virus identified in April 2009, commonly referred to as "swine flu." It is thought to be a mutation ("reassortment") of four known strains of influenza A virus subtype H1N1: one endemic in humans, one endemic in birds, and two endemic in pigs (swine).[70] The source of the outbreak in humans is still unknown, but cases were first discovered in the U.S. and soon after in Mexico, which had a surge of cases, many of them fatal. As a result, the U.N.'s World Health Organization (WHO), along with the U.S. Centers for Disease Control and Prevention (CDC), expressed concern that this could become a worldwide flu pandemic, with WHO raising its alert level to "Phase 5" out of the six maximum, indicating that a pandemic was "imminent."

According to the CDC, it is not yet clear how serious this new virus actually is compared with other influenza viruses, although on May 26th they stated that new cases in the U.S. have probably peaked, and most cases throughout the world have so far been mild relative to "seasonal flus." But because this is a new virus, most people will not have immunity to it, and illness may eventually become more severe and widespread in different demographic and population groups as a result. The H1N1 flu mainly spreads in the same way that regular "seasonal influenza" spreads, which is through the air from coughs and sneezes or touching those infected. It cannot be transmitted from eating cooked pork or by being in close contact with pigs.

As yet there is no vaccine available to prevent infection although companies are in the planning stages for having one available later this year. But there is concern that the virus could mutate again over the coming months, leading to a new and potentially more dangerous flu outbreak later in the year, and a vaccine that will be less effective in preventing its spread. Health officials in the U.S. point out that the "horrific" 1918 flu epidemic, which killed 20 million people in the United States alone, was preceded by a mild "herald" wave of cases in the spring.

As of May 26, the virus had spread to more than 46 countries; however, over 80% of reported deaths have taken place in Mexico. This has led to speculation that Mexico may have been in the midst of an unrecognized epidemic for many months prior to the current outbreak. According to the CDC, the fact that the flu's infection activity is now monitored more closely may help explain why more flu cases than normal are being recorded in Mexico, the United States and other countries. About half of all influenza