U.S. health officials have confirmed 20 deaths from the new strain of H1N1 flu, with more than 11,000 confirmed or probable cases.

Three U.S. deaths were reported on Wednesday - two in New York and one in Connecticut.

Officials at the U.S. Centers for Disease Control and Prevention reported 11,054 confirmed and probable cases with 17 deaths on Wednesday - before the three new deaths were reported. But CDC officials have said the confirmed cases represent only a tiny proportion of actual infections.

Globally, the World Health Organization reports the new swine flu virus has infected more than 19,000 people in 64 countries, killing 117. This number also did not include the three new deaths.

“Laboratory-confirmed cases represent only a fraction of the likely number of cases in the state because many persons with mild symptoms do not seek care from a doctor or hospital but recover at home,” the Connecticut Department of Public Health said in a statement.

The CDC estimates more than 100,000 Americans are infected with the virus, with most cases mild. New York and the region that includes Alaska, Idaho, Washington and Oregon had “elevated” influenza activity while outbreaks were on the downswing elsewhere in the country, the CDC said.

Health experts worry that the new flu could turn into a more dangerous form, perhaps in the northern hemisphere’s autumn months, and are preparing a vaccine and stockpiling antiviral drugs just in case.

President Barack Obama has asked Congress for another $2 billion, on top of $1.5 billion he sought earlier, to help prepare for an epidemic.

U.S. Department of Agriculture officials said they would step up surveillance for influenza among pigs. The virus appears to have originated in pigs and such viruses are common in swine. They can pass from humans to pigs and from pigs to humans.

WASHINGTON (Reuters)