A woman from Texas has become the first US resident believed to have died from swine flu.
The woman – from Cameron County, close to the US border with Mexico – died earlier this week, the Texas Department of State Health Services said.
But in a statement it added that she had been suffering “chronic underlying health conditions”.
It is the second confirmed swine flu death outside Mexico. A Mexican toddler died of the virus in the US in April.
The unnamed woman who died was in her 30s, reported Associated Press news agency.
There are 61 confirmed cases of H1N1 flu reported in Texas, said the DSHS.
The World Health Organization (WHO) said earlier that 1,490 swine flu cases had been verified in 21 countries.
After Mexico, the US has seen the greatest number of laboratory-confirmed infections, at 403.
The WHO has urged nations to remain vigilant, saying a global pandemic remained a threat.
It points out that the number of infections has continued to grow.