Pandemic prevention

As cases of the new type A influenza virus H1N1, commonly called swine flu, increase around the world, experts remain uncertain whether the virus will develop into an outbreak on the scale of previous pandemics.

The number of people infected with the new swine flu virus will increase but likely not at "an explosive rate," Joerg Hacker, the head of the Robert Koch Institute, Germany's infectious disease authority, said on Monday.

The World Health Organization has said the virus, which appears to be easily transmitted from human-to-human, has devastating potential.

Poorly understood disease

"New diseases are, by definition, poorly understood," WHO head Margaret Chan said in a statement. "Influenza viruses are notorious for their rapid mutation and unpredictable behavior."

Virologists have said it's difficult to predict the danger posed by new, largely unstudied viruses. The current swine flu is, however, related to the H1N1 virus that caused the Spanish Flu, which claimed at least 25 million lives between 1918 and 1920, as well as the Russian Flu, which killed some 700,000 people in the late 1970s.

The current virus' ability to be transmitted from one human to another convinced the WHO last week to raise the status of swine flu on it pandemic alert to five, the second-highest possible level. Phase five of the WHO's ranking calls on all countries to activate their pandemic preparedness plans and remain on high alert for unusual outbreaks of influenza-like illness and severe pneumonia.

The virus has proven to be most deadly in Mexico, where it originated. Of the 985 suspected swine flu infections in 20 countries around the world, 25 people have died of the virus in Mexico and another person in the United States, according to WHO statistics.

But Mexican Health Minister Jose Angel Cordova has said the virus reached its peak between April 23 and 28, and may prove to be no more dangerous than other influenza viruses.

Though currently unclear, researchers will continue working to uncover why the virus took on deadly proportions in Mexico but remained largely treatable in other countries, Klaus Osterrieder, a professor for virology at Berlin's Freie Universitaet, told Deutsche Welle.

How swine flu spreads and attacks the body

Two key virus components scientists will be studying when examining how the swine flu virus is spreading will be glycoprotein hemagglutinin (H) and the enzyme neuraminidase (N).

Hemagglutinin makes up about 80 percent of the virus' surface and helps the virus attach to the body's cells and, ultimately, make a person sick. Neuraminidase enzymes help viruses pathogens enter cells.

By evaluating these substances, researchers can determine where the virus came from, what known viruses it is related to and possible treatments for those affected as well as ways to prevent more people from being infected.

There are 16 different known types of hemagglutinin and nine of neuraminidase enzymes, combinations of which scientists then use to name viruses, such as the current H1N1 swine flu or the H5N1 avian flu.