NAPA, Calif. -- Napa County health officials said Friday afternoon they are taking steps to identify and track the previously unknown strain of swine flu that has been reported in Mexico, Texas and Southern California should it spread to Napa County.

The new swine flu strain has been attributed to 20 of 68 flu-related deaths in Mexico, Mexican health officials said.

Two children, ages 8 and 9, contracted the swine flu in Southern California but have recovered, said Dr. Mark Horton, Director of the California Department of Public Health. There have been a total of six reported cases in California, four in San Diego County and two in Imperial County.

Napa county hospitals and emergency departments have been alerted to watch for patients who report flu-like symptoms and to take samples that will be tested for the swine flu A (H1N1) virus, Napa County health officials said.

"For now, residents should continue typical flu precautions, such as frequent hand washing, sneezing or coughing into your sleeve rather than your hands, staying away from people who are ill and staying home when you are sick," Dr. Karen Smith, Napa County Public Health Officer said in a news release.

"Local, state and federal officials are working together to access the scope of the virus' spread and the severity of the illness it causes, and we'll alert people quickly if more stringent precautions become necessary," Smith said.

Swine flu is a respiratory disease of pigs caused by type A influenza virus that regularly causes influenza in pigs, Napa County health officials said.

Swine flu viruses cause high levels of illness and low death rates in pigs, health officials said. Typically, humans who contract swine flu have been in contact with or close to pigs but with the new strain, contact with pigs does not appear to be necessary, Napa County health officials said.

Neither of the two children in Southern California who contracted the swine flu had contact with pigs, California Department of Public Health said.

People who develop an illness with fever and respiratory symptoms should contact their health care provider, the Napa County Public Health Division said.

Those symptoms include cough and runny nose, and possibly other symptoms such as body aches, nausea or vomiting or diarrhea. A health care provider will determine if flu testing is needed, the health division said.

Napa County Public Information Officer Elizabeth Emmett said "there is no indication yet that we should be concerned about any particular population (in Napa County)."

Migrant workers who work in Napa and Sonoma counties during the grape-growing season have likely been here since bud break a few weeks ago, Emmett said.

Some of them, however, may be concerned about relatives in Mexico, Emmett said.