U.S. Swine Flu Cases Surpass 60

April 29 -- TUESDAY, April 28 (HealthDay News) -- The number of confirmed cases of swine flu in the United States continued to climb Tuesday, to 64, with all the bulk of the new cases coming from the New York City high school that had previously reported 18 cases of the infectious disease, U.S. health officials said.

"There are 64 confirmed cases in the United States in five states," Dr. Richard Besser, acting director of the U.S. Centers for Disease Control and Prevention, said during an afternoon teleconference. "Forty-five in New York, one in Ohio, two in Kansas, six in Texas and 10 in California.

Although cases in the United States continue to be mild, more severe cases are expected, Besser said, adding, "as we move forward, I fully expect we will see deaths."

California authorities were investigating whether two recent deaths were linked to the outbreak, according to published reports.

Besser said three people have been hospitalized in California and two in Texas. The incubation period for the U.S. cases is two to seven days, which, he said, "is typical for what you see with an influenza virus."

The majority of new cases in New York continued to come at St. Francis Preparatory School in Queens. Some students who have come down with the infection had been to Mexico during a spring break to Cancun, the Associated Press reported.

As with the previously tested strains of the never-before-seen swine flu virus, new testing found that the pathogen remains susceptible to the two common antiviral drugs Tamiflu and Relenza, according to an April 28 dispatch from the CDC's Morbidity and Mortality Weekly Report.

The new flu strain is a combination of pig, bird and human viruses, prompting worries from health officials that humans may have no natural immunity to the virus.

Meanwhile, the AP reported Tuesday that the epidemic had crossed new borders, with the first cases confirmed in the Middle East and the Asia-Pacific region. And the number of deaths in Mexico -- thought to be the source of the outbreak that continues to reach around the world -- surpassed 150. Mexico is the only country to report deaths caused by the new swine flu strain of flu. Cases in all other countries have been described as mild.