Officials say the first confirmed death in the U.S. from swine flu was a 23-month-old child from Mexico City who died in Houston.
The Texas Department of State Health Services said the boy had underlying health problems when he traveled to Texas on April 4 to visit relatives in Brownsville, which is on the border with Mexico. He developed a fever and other flu symptoms on April 8 and was admitted to a Brownsville hospital a few days later.
After becoming ill in Brownsville, the child was taken to a Houston hospital and died Monday night, said Kathy Barton, a spokeswoman for the Houston Health and Human Services Department.
In North Texas, there are three confirmed cases of swine flu and six probable cases in Dallas County, officials said Tuesday. The county is taking extra steps to try to curtail further spread of the virus -- including reaching out to bus lines bringing people into the city.
Additionally, three schools have closed their campuses, including Cleburne High School, after probable cases of swine flu were discovered.
Besser said in a nationally broadcast network interview that health authorities had anticipated that the virus would cause deaths, and said that "as a pediatrician and a parent, my heart goes out to the family."
But Besser said on NBC's "Today" show Wednesday morning that it's too soon to say if the death in Texas suggests the virus is spreading to more states. Nor would he say whether officials think it will become a nationwide problem.
He also said he does not believe the flu strain has become more dangerous.
Besser went on to note that even with seasonal flu, there are always some people who can't resist it very well, and said authorities need to learn more about the threat.
Children, especially those younger than age 5, are particularly vulnerable to flu and its complications, and every year children die from seasonal flu. As of April 11, CDC had received reports of 53 seasonal flu-related deaths in children during the current seasonal flu season.
According to the CDC, more than 20,000 children younger than age 5 are hospitalized every year because of seasonal flu. In the 2007-08 flu season, the CDC received reports that 86 children nationwide died from flu complications.
Sixty-six infections of swine flu had been reported in the United States before the report of the toddler's death in Texas.
The world has no vaccine to prevent swine flu infection, but U.S. health officials aim to have a key ingredient for one ready in early May.
An actual vaccine could be months away.