Before Édgar fell ill, another person in San Diego may have been affected, said Dr. Miguel Ángel Lezana, Mexico’s chief government epidemiologist.

Even now, Édgar’s mother, María del Carmen Hernández, said she received conflicting accounts of the exact illness that kept her son in bed for three days. No one has explained what she should be doing to keep him and the rest of the family healthy, she said, signs that Mexico’s response effort may be spotty, especially in rural areas.

“Some people are saying my boy is to blame for everyone else in the country getting sick,” said Mrs. Hernández, 34, a blank stare on her face as she recounted the family’s ordeal. “I don’t believe that. I don’t know what to think.”

There was a modest increase on Tuesday in new cases of swine flu reported around the world.

In the United States, the number of confirmed cases rose to 64, from Monday’s count of 50, according to a news briefing by Dr. Richard E. Besser, acting director of the Centers for Disease Control and Prevention. The total includes 45 cases in New York State. There have been no deaths from the disease in the United States, but five people have been hospitalized for treatment.

Mexico remains the hardest hit. Late Tuesday, the Health Ministry put the number of suspected cases at 2,498, and the suspected number of deaths at 159.

In La Gloria, a town that has a major pig farming industry, two children died of the flu in March and early April, though the authorities said they had yet to determine whether it was the same strain that infected Édgar and spread widely to other locales. That and other questions have left residents here unnerved and confused.