Health officials across the Bay Area say they are actively monitoring the spread of swine flu in the U.S., though no cases have been reported locally.
Dr. Richard Besser, acting director of the U.S. Centers for Disease Control and Prevention (CDC), said Monday that his agency has confirmed 40 cases of the respiratory disease in five U.S. states including California, with none of the cases producing serious illness.
The number of confirmed cases doubled after further testing revealed the additional cases in New York City. According to the CDC, swine flu cases have been confirmed in New York, California, Texas, Ohio and Kansas. Only one person has been hospitalized and all of those infected have since recovered. The CDC also confirmed several cases in Mexico.
The reported cases in California were mostly in San Diego County and Imperial County.
Besser said that late Monday, "out of an abundance of caution," the CDC will issue a travel advisory recommending avoiding nonessential travel to Mexico.
He said that "much is unknown" about how or where this strain of swine flu originated and that the agency was aggressively investigating the situation, in collaboration with international, state and local health officials.
Influenza, including swine flu, is spread mainly from person to person through coughing or sneezing, and health officials recommend frequent hand washing and covering one's mouth when coughing or sneezing.