Much remains unknown about the new swine flu virus - most notably how lethal it is and why it seems so much deadlier in Mexico than anywhere else. -- PHOTO: AP
ATLANTA - MUCH remains unknown about the new swine flu virus - most notably how lethal it is and why it seems so much deadlier in Mexico than anywhere else.
American health officials believe they are getting closer to answering those questions, or, at least, to ruling out wrong-headed theories.
4 hypotheses ruled out
DR WEBBY and others do not believe the swine flu in Mexico is different from what's been seen in US patients. The virus samples in both countries match.
The CDC sent four epidemiologists and one lab scientist to Mexico over the weekend to investigate the disease there, and the agency expects to send a half-dozen more people this week, said Dr Dowell, of the CDC.
'We've begun to knock off hypotheses,' said Dr Scott F. Dowell, director of global disease detection with the US Centers for Disease Control and Prevention.
Among the factors disease detectives have discounted are Mexico's air pollution, secondary infections and poor health care. But they still do not know why so many Mexicans have died, although it could be because many more people actually have had the virus than health officials realise.
In Mexico, the virus is suspected of killing more than 150 people and sickening more than 2,400. Recent information suggests swine flu-related hospital admissions and deaths may have peaked and are declining, but no other country has shown any numbers close to those seen in Mexico.
The only other country to report a swine flu death is the United States, and that involved a toddler from Mexico who was visiting Texas with his family.
The leading theory remains that the virus itself is not significantly different in Mexico, but that the outbreak has for some reason just hit harder there, infecting more people overall. The more people who are infected, the more likely there will be severe cases and even deaths.
When the Mexican health secretary spoke this week about a 6 or 7 per cent death rate, his figures were based on the number of deaths divided by the number of suspected infections. But authorities cannot be certain how many people have been infected, especially those who suffered only mild symptoms.
Mexican authorities have not tried to count mild cases, focusing instead on the severely ill and the dead. So the death rate may be much lower than 6 or 7 per cent - and probably is, according to some experts.
A 6 to 7 per cent death rate would make the Mexican swine flu nearly three times deadlier than the worst flu pandemic in the last 100 years - the 1918 Spanish flu, which killed an estimated 20 million to 50 million people worldwide. That seems unbelievably high for this new virus, said Richard Webby, a flu researcher at St. Jude Children's Research Hospital in Memphis. -- AP
