Global Testing Shows No Variation in Swine Flu Virus

THURSDAY, June 4, 2009 (HealthDay News) -- In what would seem to be some encouraging news in the ongoing H1N1 swine flu outbreak, a leading federal health official said Thursday that samples of the virus from points around the globe are genetically identical to the strain found in the United States.

"We have tested isolates from a wide geographic area, from the Americas, Europe, from Asia and New Zealand and we are not seeing variations in isolates from the genetic testing we do here," Dr. Anne Schuchat, the Centers for Disease Control and Prevention's interim deputy director for science and public health program, said during a press conference.

While infections caused by the virus continue to be relatively mild and patients recover quickly, health officials have warned that the virus could mutate into a more virulent form, putting greater numbers of people at risk.

The World Health Organization said Tuesday that it was weighing whether to declare a global pandemic, with more cases of the H1N1 swine flu surfacing in the Southern Hemisphere -- where flu season is just beginning -- and outside North America.

The vast majority of infections and deaths have occurred in Mexico -- the source of the outbreak -- and the United States. But person-to-person transmission in now being reported in countries such as Australia (501 cases) and Chile (313 cases), as well as Great Britain, Spain and Japan, according to published reports.

"We still are waiting for evidence of really widespread community activity in these countries, and so it's fair to say that they are in transition and are not quite there yet, which is why we are not in phase 6 yet," WHO flu chief Dr. Keiji Fukuda said during a press conference at the agency's headquarters in Geneva, Switzerland.

Phase 6 is the highest alert on WHO's scale, representing a global epidemic. In terms of the geographic spread of swine flu, the world is "at phase 5 but getting closer to phase 6," Fukuda said, the Associated Press reported.

The WHO also was debating whether to add a second measure that indicates how dangerous the H1N1 swine flu virus is -- rather than just how widespread -- after several countries expressed concerns that declaring a global pandemic could cause mass confusion and panic even though it's still not clear how dangerous the virus will be, the news service said.

To date, the virus has caused 19,273 cases of infection in 66 countries, but just 117 deaths, 97 of them in Mexico, the WHO reported Wednesday.

Since the outbreak started in April, health officials in the United States have said that infections have been mild for the most part. Testing has found that the H1N1 virus remains susceptible to two common antiviral drugs, Tamiflu and Relenza.

The U.S. Centers for Disease Control and Prevention was reporting Wednesday a total of 11,054 cases in all 50 states and the District of Columbia and Puerto Rico, including 17 deaths. The agency said that confirmed cases of H1N1 swine flu represent about one in 20 of actual cases, bringing the total probable number of cases in the United States to about 200,000.

During the next few months, CDC scientists will be looking to see if the virus mutates or becomes resistant to antiviral medications, or is more easily spread among people. The flu season is winding down in the Northern Hemisphere but is just beginning in the Southern Hemisphere.

Some older people may have partial immunity to the H1N1 swine flu virus because of possible exposure to another H1N1 flu strain that circulated prior to 1957, according to the CDC.

A vaccine for the swine flu virus could be ready by October, if research and testing proceed as planned this summer, agency officials said.

More information

For more on swine flu, visit the U.S. Centers for Disease Control and Prevention.