Why is the swine flu more deadly in Mexico??

A new swine flu virus has surfaced, first in Mexica, then the States,  Canada and New Zealand .

Flu viruses mutate  and new strains appear continously and every epidemic in one area has the potential of becoming world wide epidemic , because of  the tremendous number of people travel by planes and moving across countries and continents nowadays.

In any influenza epidemic, many will die but most will recover. The groups with the highest mortality were usualy the very old and the very young, and those with compromised immunity, like those on immunosuppreesive drugs, cance rpateints, reanl dialysis cases etc.

BUt in this case, something baffling is occuring.  In mexico, most that died were between 20 to 40, a group that normally do not succumb to mortality as easily as  the older and the younger groups..

I find it strange that cases in US involving younger and older patients suffered much milder disease than those in Mexico, which defies all the conventional medical wisdom really.

Are there 2 different strains of this virus? are there 2 epicenters? well, we need to have more info before making any conclusion.

I will post part of an AP  news article here:

ATLANTA – Why has the swine flu engulfing Mexico been deadly there, but not in the United States?

Nearly all those who died in Mexico were between 20 and 40 years old, and they died of severe pneumonia from a flu-like illness believed caused by a unique swine flu virus.

The 11 U.S. victims cover a wider age range, as young as 9 to over 50. All those people either recovered or are recovering; at least two were hospitalized.

“So far we have been quite fortunate,” said Dr. Anne Schuchat of the U.S. Centers for Disease Control and Prevention on Saturday, just hours before three new U.S. cases were confirmed.

Health experts worry about a flu that kills healthy young adults — a hallmark of the worst global flu epidemics. Deaths from most ordinary flu outbreaks occur among the very young and very old.

Why the two countries are experiencing the illness differently is puzzling public health experts, who say they frankly just don’t know.

It may be that the bug only seems more deadly in Mexico.

And while experts believe Mexico is the epicenter of the outbreak, they’re not certain if new cases are occurring or if the situation is getting worse. They also don’t know if another virus might be circulating in Mexico that could be compounding the problem.

A big question is, Just how deadly is the virus in Mexico?

The seasonal flu tends to kill just a fraction of 1 percent of those infected.

In Mexico, about 70 deaths out of roughly 1,000 cases represents a fatality rate of about 7 percent. The Spanish flu pandemic of 1918-19, which killed an estimated 40 million worldwide, had a fatality rate of about 2.5 percent.

The Mexican rate sounds terrifying. But it’s possible that far more than 1,000 people have been infected with the virus and that many had few if any symptoms, said Dr. Michael Osterholm, a prominent pandemic expert at the University of Minnesota.