U.S. Now Leads World in Swine Flu Cases

May 11 -- MONDAY, May 11 (HealthDay News) -- Confirmed cases of H1N1 swine flu in the United States climbed to more than 2,500 by Monday, and the U.S. now surpasses Mexico as the country most affected by the outbreak, according to World Health Organization figures.

The number of deaths in the United States linked to the illness rose to three over the weekend, with health officials in Washington state reporting late Saturday that an unidentified man in his 30s had succumbed to the infection.

In a state Department of Health news release, officials said the man, who had an underlying heart condition, died last week with what appeared to be complications from the swine flu, the Associated Press reported.

The man's death came after two prior fatal U.S. cases of swine flu: a 33-year-old woman in Texas, and a Mexican toddler who had been treated at a Texas hospital. Both of those individuals also had chronic underlying medical conditions.

The swine flu count in the United States now stands at 2,532 confirmed cases in 44 states, the U.S. Centers for Disease Control and Prevention said on Sunday. On Saturday, CDC officials said those numbers included 104 hospitalizations. The vast majority of cases are mild, however.

"We had expected more cases and we are continuing to find them," Dr. Anne Schuchat, interim deputy director for science and public health program at the Centers for Disease Control and Prevention, said during a Saturday teleconference.

The jump in confirmed cases is partly due to the reduction in the backlog of testing for infections. But the number of confirmed cases is probably an underestimation of the total number of actual cases as the virus continues to spread, Schuchat said.

"Transmission here in the U.S. is ongoing. This is a very easily transmittable virus," she said. "Fortunately, the severity of illness that we're seeing, at this point, doesn't look as terrible as a category-five pandemic or the severely devastating impact some had feared. But influenza viruses are unpredictable and can change over time. Going forward, it's really important to us that we pay attention to how this virus may or may not change."

Because the new swine flu virus is a highly unusual genetic mix of bird, flu 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.

And, while most of the infections continue to cause only mild illness, similar to the seasonal flu, and virtually all patients recover quickly and fully, federal officials warned Friday that the swine flu outbreak in the United States is far from over.

"I want to address an issue that's been concerning me, that has to do with a sense of having dodged a bullet, a sense that this is over," Dr. Richard Besser, the CDC's acting director, said during a Friday teleconference. "While we have seen a lot of encouraging news in terms of severity, we continue to see hundreds and hundreds of new cases each day," he said.

While the swine flu -- technically known as the H1N1 virus -- is similar to seasonal flu, there are some important differences, Besser said. "One thing we are seeing, unlike seasonal flu, a higher percentage seem to be having vomiting and diarrhea," he said.

Besser said last week that most new cases of swine flu in the United States are now caused by person-to-person transmission and not some link to Mexico, as was the case when the outbreak began more than two weeks ago. Mexico is believed to be the source of the outbreak.

Testing has found that the swine flu virus remains susceptible to two common antiviral drugs, Tamiflu and Relenza, according to the CDC.

So far, U.S. deaths linked to swine flu occurred in individuals with multiple underlying health problems, according to a CDC report released Thursday by the New England Journal of Medicine.

On Saturday, health officials in Costa Rica reported the first swine flu-related death in that country -- a 53-year-old man who also suffered from diabetes and heart disease. The death marked the first swine flu-linked death outside North America, according to the AP.

U.S. health officials last week said the outbreak of swine flu appears similar to the seasonal flu in its severity, so schools across the nation should remain open and any schools that did close should reopen.

On Monday, the World Health Organization was reporting 4,694 confirmed cases of swine flu in 30 countries, with Canada, Spain and the United Kingdom having the most cases outside of the United States and Mexico.

(As of May 11, 2009, 11:00 AM ET)

laboratory
confirmed
cases

*includes the District of Columbia

**One case is resident of Ky. but currently hospitalized in Ga.

Source: U.S. Centers for Disease Control and Prevention