May 14 (HealthDay News) -- U.S. health officials said they're seeing some complications among pregnant women as the swine flu continues to spread across the country, and that this high-risk group needs to take antivirals as soon as infection is suspected.
"Pregnant women are at higher risk of complications of influenza, whether it's the seasonal influenza or pandemics of the past. We are also seeing some severe complications in women with this year's novel H1N1 virus," Dr. Anne Schuchat, the U.S. Centers for Disease Control and Prevention's interim deputy director for science and public health program, said during a Tuesday afternoon teleconference.
The CDC is investigating 20 cases of pregnant women with the swine flu, several of whom experienced complications, Schuchat said. Complications can include pneumonia, dehydration and premature birth.
"It is very important that doctors who are caring for pregnant women they suspect may have influenza, that they issue prompt treatment with antiviral medicines," she said.
Doctors can be reluctant to treat pregnant women with antiviral drugs such as Tamiflu and Relenza, and pregnant women may be reluctant to take them out of fear that they may pose a risk during pregnancy, Schuchat said. "Experts who have looked into this situation strongly say that the benefits of using antiviral drugs to treat influenza in a pregnant woman outweigh the theoretical concerns about the drugs," she said.
Of the three swine-flu related deaths in the United States, one involved a 33-year-old pregnant woman from Texas who had other health problems before she was infected with the virus.
Schuchat said Monday that federal health officials were shifting their focus from individual cases of infection to trying to project what is likely to occur with the virus in the fall. Because the new virus -- technically called H1N1 -- is a highly unusual genetic mix of bird, pig and human viruses, health officials worry that it could continue to mutate and return in a more virulent form for next winter's flu season.
The CDC is concerned with what will happen as this new virus moves into the Southern Hemisphere, where the flu season is about to start. The agency is also preparing for the virus' likely return in the fall to the Northern Hemisphere, Schuchat said.
As of Wednesday, there were 3,352 confirmed cases in 45 states and the District of Columbia, with three confirmed deaths. On Tuesday, the CDC said 116 people were hospitalized with swine flu. All three patients who have died in the United States had underlying health problems before their infection with the flu.
Testing has found that the swine flu virus remains susceptible to two common antiviral drugs, Tamiflu and Relenza, according to the CDC.
Schuchat said Monday that the confirmed cases were likely just the tip of the iceberg. Many people who become ill don't seek medical attention and are never tested for this strain of flu. "The numbers we are reporting are a minority of the actual infections that are occurring in the country," she said.
Reporting Monday in the journal Science, researchers from the World Health Organization said the swine flu epidemic has pandemic potential and is likely to be comparable to other 20th century pandemics -- at least in terms of its spread.
The report also suggested that the true number of -- largely unreported -- swine flu infections in Mexico, the outbreak's epicenter, possibly had already reached 32,000 by the end of April. The World Health Organization's official tally for Mexico stood Thursday at 2,059 confirmed human infections, including 56 deaths.
The United States has now surpassed Mexico -- believed to be the source of the outbreak -- as the country most affected by the epidemic, according to WHO statistics. As of Thursday, the agency was reporting 6,497 confirmed cases of swine flu in 33 countries, with Canada, Spain and the United Kingdom having the most cases outside of the United States and Mexico.
Meanwhile in Mexico, federal health officials said Tuesday that the worst seemed to be over despite more deaths. The country's death toll rose Tuesday to 58 deaths and 2,282 confirmed cases of swine flu -- a rise of two deaths and 223 more cases since Monday. But Health Secretary Jose Angel Cordova said this reflects a testing backlog: The last confirmed case was May 8, the Associated Press reported.
Also on Tuesday, one WHO expert expressed support for the more selective use of antiviral medicines such as Tamiflu and Relenza. As reported by the AP, Dr. Nikki Shindo said that whereas some European countries are using these drugs "aggressively" throughout the population, "countries like Mexico and the United States, they are trying to save the treatment for patients with underlying conditions and also the other groups at risk, such as pregnant women."
Swiss drug maker Roche Holding AG said it was donating to the WHO enough Tamiflu for 5.65 million people.
SOURCES: May 12, 2009, teleconference with Anne Schuchat, M.D., interim deputy director, science and public health program, U.S. Centers for Disease Control and Prevention; Associated Press