A 22-month-old boy has died in Houston from swine flu as the outbreak continues to expand in the U.S. and abroad, the Centers for Disease Control and Prevention (CDC) reports today. This is not the first time swine strains of influenza have claimed lives in the U.S., but previous cases appear to have occurred primarily in people exposed to sick pigs.  

The total number of confirmed human cases of the new swine flu strain in the U.S. has now reached 91, according to the CDC Web site: 51 in New York City, 14 in California, one in Arizona, one in Indiana, two in Kansas, two in Massachusetts, two in Michigan, one in Nevada, one in Ohio, and 16 in Texas. The Texas tally includes three teenagers from Guadalupe County and two small children and a 24-year-old in Dallas County, according to Emily Palmer of the Texas Department of State Health Services.

The child who died was from Mexico City, according to a statement by the state health services department. On April 4, the boy and his parents took a flight from Mexico City to Matamoros, Mexico, to see family members in Brownsville, Tex., which is just north of the border. After developing flu-like symptoms four days later, the boy was admitted to a Brownsville hospital and later transferred to one in the Houston area, the statement says. Health officials do not think his infection was contagious the day he took the commercial flight, according to the statement.

Deaths from swine flu, although rare, are not new to the U.S. In 1988, a 32-year-old pregnant woman died of pneumonia caused by the H1N1 swine flu virus. Four days before falling ill, the woman had attended a swine show displaying several pigs with flu-like symptoms at a county fair, according to the CDC. In 1976, the death of a soldier during a swine flu outbreak at Fort Dix, N.J., touched off an infamous panic.

State and federal health officials have identified several non-fatal cases of swine flu over the past several years. Last fall, researchers from Wisconsin published a case report in Emerging Infectious Diseases describing a 17-year-old boy who in 2005 developed mild flu symptoms after helping a family member butcher pigs. Subsequent lab tests revealed he had been infected with swine flu. And a 2002 study indicates that such infections may be common among farm workers.

Historically, the CDC has received about one human swine flu report every one or two years, but that number has recently increased; between December 2005 and February of this year, the agency received 12 reports of human swine flu.

See our in-depth report for more on the swine flu outbreak.