Swine flu kills 60 in Mexico; 6 cases in state
Erin Allday, Chronicle Staff Writer
Saturday, April 25, 2009

California doctors and other health experts are on the lookout for cases of a new strain of swine flu, a potentially dangerous virus that has reignited fears of a pandemic flu outbreak after killing about 60 people in Mexico and sickening eight people in the United States.

Hospitals and public health departments throughout California, where six of the American cases have been found, were told Friday to increase surveillance of the rare strain of flu that combines genetic material from humans, pigs and birds.

State and federal health officials said there is little cause for alarm in the United States at this point - all of the U.S. cases have been mild, and the flu has been responsive to drugs. Everyone infected so far has fully recovered; one woman was hospitalized, but she had an underlying condition that complicated her case, state public health officials said.

But the cases in Mexico have been startlingly severe, with more than 800 cases of pneumonia in the capital alone that are suspected to be related to the swine flu, according to the World Health Organization.

Healthy adults hit

Also worrisome is that most of the illness has been in healthy young adults, which is unusual with influenza outbreaks. Government officials have closed schools in Mexico City, and people are being told to avoid crowds.

"My level of concern is significant," said Dr. Martin Fenstersheib, the health officer for Santa Clara County. "We have a novel virus, a brand-new strain that's spreading human to human, and we are also seeing a virulent strain in Mexico that seems to be related. We certainly have concerns for this escalating."

It's unclear how people in Mexico and the United States have caught the virus. Swine flu is typically transferable from direct contact with a pig, but none of the U.S. patients had such contact. That likely means that the virus has started to spread from human to human.

That's what concerns public health experts, who have long worried over the potential for a deadly pandemic flu outbreak. Different viruses can infect one animal and shake up the genetic material, causing a new virus. If such a virus is able to spread among humans and contains viral material that humans haven't developed a natural resistance to, the result could be widespread, serious illness.

Bird flu has been the top concern, because humans have almost no resistance to that virus, and cases where humans have caught the flu strain from a bird have been very severe and often deadly. So far bird flu hasn't found a way to spread from human to human.

"This is what everyone's worried about with bird flu. After a decade it hasn't happened, and I'd sort of written it off," said Dr. Larry Drew, director of the UCSF virology lab. "But if it's now an attribute of swine flu, why couldn't it become an attribute of bird flu? It's kind of frightening."

U.S.-Mexico link unclear

The connection between the cases in Mexico and the United States is still uncertain, although the Centers for Disease Control on Friday reported that at least seven samples of the virus from Mexico are "very similar" to the strains in the United States. But so far it's not known how many of the people who are sick in Mexico have swine flu or a form of seasonal influenza.

The eight people infected in the United States all live near the border - six are in San Diego and Imperial counties, and two are in San Antonio. Public health experts said it's likely there are more cases in the United States. Doctors don't typically take samples from flu patients for testing, and the recent swine flu cases were only caught because the patients were involved in health programs that were testing new diagnostic procedures.

The symptoms of swine flu are similar to seasonal influenza, including fever, cough, sore throat and in rare cases vomiting and diarrhea. People who believe they have the flu should stay home, health experts said. If they are very sick, they should see a doctor and make sure they report if they've been to Mexico in the past few days or have had contact with anyone from Mexico.

"People should stay home from work, and children should really not be at school if they are sick and have a fever," said Dr. Roger Baxter, co-director of the Kaiser Permanente Vaccine Study Center in Oakland. "If you're not sick, should you avoid crowds and take precautions like that now? We're not there yet."

Signs of possible swine flu

-- Flulike symptoms, including fever, sore throat, cough, and possibly vomiting and diarrhea.

-- Recent travel to Mexico, or contact with someone who has been to Mexico recently.

-- Recent travel to San Diego or Imperial counties in Southern California, or contact with someone from there.

-- Recent plane travel to airports in affected areas, including Mexico, San Diego and San Antonio.

What to do if you're sick

-- If you have a fever, stay home. Do not go to work, and do not send sick children to school.

-- If symptoms worsen, contact a doctor. Be sure to report other risk factors such as recent travel to Mexico.

For more information

-- The Centers for Disease Control: links.sfgate.com/ZGWY

-- California Department of Public Health: links.sfgate.com/ZGWZ

-- Center for Infectious Disease Research and Policy: www.cidrap.umn.edu.