Swine flu -The influenza virus
“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 the virus “most likely” 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 on other continents for years before infecting humans.
The outbreak began in Mexico, with evidence that Mexico was already in the midst of an epidemic for months before the outbreak was recognized. Soon after, their government closed down most of Mexico City’s public and private offices and facilities to help contain the spread. In early June, as the virus spread globally, the World Health Organization (WHO) declared the outbreak to be a pandemic, but also noted that most illnesses were of “moderate severity.”
The virus has since spread to the Southern Hemisphere which entered its winter flu season, and to many less developed countries with limited healthcare systems. Because the virus was spreading with “unprecedented speed”, and many clinics were overwhelmed testing and treating patients, WHO stopped requiring countries to report all cases, but is still monitoring unusually large outbreaks.
