U.S. CDC fears more swine flu cases in fall

By Julie Steenhuysen and Maggie Fox

CHICAGO/WASHINGTON (Reuters) - The new H1N1 swine flu virus is still circulating and will likely cause more disease in the fall, when schoolchildren return from summer break, a U.S. Centres for Disease Control and Prevention official said on Friday.

The virus, which has been declared a pandemic, is causing severe disease and deaths in older children and younger adults in the Southern Hemisphere, just as it has in the United States, the CDC's Dr. Anne Schuchat said.

"We are expecting an increase in influenza or respiratory illness that could be earlier than what we see with seasonal influenza," Schuchat told reporters in a telephone briefing.

"This year we've been seeing this 2009 H1N1 influenza virus circulating in the summer months. We've seen it in camps and military units. I'm just expecting when school reopens and kids get back together, we expect to see an increase."

Schuchat said the virus, which officials estimate has infected millions of people, was thriving in spite of the heat and humidity of summer. Usually respiratory viruses such as flu do not circulate well in summer months.

Schuchat said this was probably because so many people do not have immunity to H1N1, and not because the virus has some unusual biological properties.

Pregnant women also often have more serious symptoms and are more likely to die, just as with seasonal flu, Schuchat said. The same pattern is being seen in Southern Hemisphere countries like Argentina, she said.

The virus has spread fast, Schuchat said. "We have seen this virus reach every country in a matter of weeks and months and not years," she said.