Global epidemiology of H1N1 2009 influenza pandemic

Swine influenza (swine flu) is a respiratory disease of pigs caused by type A influenza virus that regularly causes outbreaks of influenza in pigs. Although it is very rarely transmitted to humans, an outbreak started in March 2009 in Mexico and spread to the other parts of the world. Research has shown very fast that, the causative agent was a new strain of H1N1 swine influenza virus. On June 11th World Health Organization (WHO) has raised the pandemic alert level to phase VI and declared that a global pandemic has started. By the date February 14th the infection has spread to 212 countries over the world and has caused the death of at least 15,921 people. Although many countries have passed the peak transmission level, the pandemic is not over, yet. The transmission is still at a significant level in North Africa, Southern Europe and East and Southeast Asia. It is known from the past pandemics that, there can be multiple waves of a pandemic therefore WHO has declared that a close follow-up is necessary during the summer and winter of 2010.