The World Health Organization hasn't yet declared swine flu a global pandemic - but already news of the unusual bug that began in Mexico is leaving people panicked and uncertain.
There is still much that experts don't understand about the epidemiology of the outbreak.
They cannot say why those infected in Mexico, where the outbreak is known as la gripe porcina, are between the ages of 20 and 50 - not a population normally vulnerable to flu. Infectious disease specialists also don't yet know why the six confirmed cases in Canada and the 40 in the United States appear to be more mild.
"This flu has never before been seen in pigs or humans, which means we don't know its capabilities," said Donald Low, medical director of Ontario's public health laboratories and chief microbiologist at Toronto's Mount Sinai Hospital. "We are seeing this flu in its very early stages and we must continue to monitor it. We don't have the epidemiology to define whether it's seasonal flu or more like the flu of 1968, where one in every 100 people died."
Still, there are specific measures people can take to avoid getting flu and to prepare for the possibility of a pandemic.
People should use "common sense," Dr. Low cautions, and not overreact. Swine flu is not transmitted through fruits and vegetables from Mexico, and you cannot get the virus from ingesting pork products.
Among the best protection against flu of any kind is frequent handwashing.
Also important is good coughing and sneezing etiquette (into your sleeve) and avoiding contact with people who are experiencing flu-like symptoms.
Flu viruses are normally transmitted through uncovered coughs and sneezes from a distance of up to one metre, and are spread by touching your mouth or nose with unwashed hands. As well, flu viruses can live on surfaces, such as a doorknob, for several hours.
Dr. Low said there is no reason to run out and buy a face mask unless you are caring for someone who has the flu. "You would be better off to buy an alcohol-based hand wash and carry it with you," he said.
Two antiviral medications, Relenza and Tamiflu, are effective in fighting this strain, known as influenza A H1N1 virus, according to the U.S. Centers for Disease Control and Prevention. These medications can block the virus's ability to replicate in the body and must be taken within the first few days that symptoms appear.
But does this mean you should run out and fill a prescription for Tamiflu?
"At this point, augmenting individual stockpiles is not all that useful as a national plan to combat a possible pandemic," advises Geoff Taylor, director of the division of infectious diseases at the University of Alberta.
Without professional guidance, people may not use the antiviral medications in the right dosage or for the specified length of time, which could lead to drug resistance or unnecessary side affects.
As well, the federal and provincial governments have stockpiled 55 million doses and outlined "priority" groups in the case of a pandemic, including those at a high risk of dying from the illness and essential service and health care workers. Individual hospitals and institutions across the country also have supplies, added Dr. Taylor, who until recently sat on the committee that developed the Public Health Agency's pandemic influenza plan.
Experts don't yet know why the virus has only killed people in Mexico. It is possible those people already had other infections, or were hospitalized after the virus became more virulent. Epidemiologists are on alert to see if the flu virus spreads to people who have not been to Mexico, which would escalate the risk substantially. Yesterday, the WHO raised its pandemic alert level from 3 to 4, saying the virus is now widespread and being transmitted in a sustained way between people.
