Swine Flu - An Emerging Pandemic?

Swine Flu is spreading.

Tests show that eight students at a Queens high school are likely to have contracted the human swine flu virus that has struck Mexico and a small number of other people in the United States, health officials in New York City said yesterday. The students were among about 100 at St. Francis Preparatory School in Fresh Meadows who became sick in the last few days, said Dr. Thomas R. Frieden, New York City’s health commissioner.

Why has Swine Flu been classified as a potential pandemic by the CDC and WHO (World Health Organization)?

First here is some background on viral pandemic. A pandemic is an epidemic of infectious disease that spreads through populations across a large region; E.g. a continent, or even worldwide. Here are a few infamous pandemics you might recall:

• Black death (bubonic plague): killed 20-30 million in 6 years; at that time a third of the total world population.
• Spansih Influenza, 1918-1919: First cases documented in March 1918. By October that fall, it had affected 20% or more of the world population. Aftermath: 50 million dead.
• AIDS: 37 million dead in twenty years.
• Typhus killed ~5 million in Russia from 1918 to 1922

Why is Swine Flu so potentially dangerous?
You might remember Avian flu (H5N1) a few years which caused quite a stir in Asisa. This virus was unable to achieve sustained and efficient human-to-human transmission. Most cases thus far have been transmitted from bird-to-human. A pandemic erupts once a virus evolves the ability to efficiently spread human to human via transmission by air .

Swine Flu is not new. (1) It can be found it persons who are in regular contact with pigs. Like Avian flu it is caused by strains of the Influenza virus (H1N1, H3N2, and H1N2). There was an outbreak in the US in 1976 at Fort Dix which infected several soldiers and in the end claimed the life of one soldier. By contrast, here are the startling numbers of the current Swine Flu outbreak:

• 1000 cases detected in Mexic with more than 80 deaths
• 11 laboratory confirmed cases in the southwestern US and in Kansas, with several suspected cases in NYC.
• 22 confirmed cases in New Zealand

Fortunately, the cases in the US have been mild and have not caused deaths unlike the cases in Mexico. In an interview on April 24, acting CDC director Richard Bessar said that it was still not known why the American cases were primarily mild disease while the Mexican cases had led to multiple deaths. Differences between the viruses or co-infection are reasons being considered.


1) Richard Besser in article More cases of swine flu reported; WHO warns of 'health emergency by Mayra Cuevas, Ann Curley, Caleb Hellerman, Elaine Quijano and Susan Candiotti dated 25 April 2009