By Rob Stein and David Brown
Washington Post Staff Writers
Saturday, April 25, 2009
An unusual strain of swine flu has been detected among victims of a large outbreak of a severe respiratory illness in Mexico, prompting global health officials, fearful of a potential flu pandemic, to scramble yesterday to try to contain the virus.
At least 1,004 people have been sickened and at least 68 have died, primarily in the sprawling capital of Mexico City, triggering officials to close all schools and universities, museums and libraries and to begin screening air travelers for symptoms before they leave the country.
Officials warned millions of residents to stay home, avoid public places and take other protective measures, such as resisting greeting people with handshakes or kisses. Drugstores reported being inundated with customers seeking face masks, and some subway riders were spotted wearing rubber gloves.
"We are very worried," Angelica Padilla, 38, a mother of a 5-year-old girl and an 8-year-old boy, said in a telephone interview from Mexico City. "This is bad."
The outbreak heightened alarm among health officials in the United States, where at least eight cases of swine flu have been detected along the U.S.-Mexican border, and elsewhere.
"It's alarming and very concerning," said Sari Setiogi, a spokeswoman for the World Health Organization in Geneva, which began an investigation of the cause and scope of the outbreak.
President Obama has been briefed about the illness, spokesman Reid Cherlin said, adding: "The White House is taking the situation seriously and monitoring for any new developments."
The illness appeared to be primarily striking young, healthy adults, a highly unusual pattern that conjured images of the devastating 1918 flu pandemic.
Officials stressed that there were no signs that anything of that scale had begun, but Setiogi said, "This is another reason we are highly concerned," noting that it is the very old and the very young who are usually most vulnerable to common seasonal flu.
The Spanish flu, which circled the world in 1918 and 1919 and killed at least 50 million people, was of the same general subtype, H1N1, as the virus in California and Mexico.
In 1976, a strain of swine flu caused illness in 13 soldiers at Fort Dix in New Jersey, killing one. Fearing a pandemic, the federal government began a mass immunization campaign, but it was halted when the virus did not spread and some vaccine recipients developed a rare neurological disorder.
The WHO dispatched a team yesterday from its Washington office to Mexico City to assist authorities, ratcheted up efforts to detect the virus elsewhere and was mobilizing to take other steps if necessary.
"We are preparing for rapid containment to prevent this outbreak from spreading further," Setiogi said.
Canadian officials confirmed that 18 of 51 specimens it received from Mexico were swine flu, and the U.S. Centers for Disease Control and Prevention in Atlanta confirmed that seven of 14 samples it received were also the unusual swine flu. A preliminary genetic analysis indicated that the Mexican samples matched those taken this week from people in Southern California and Texas.
An earlier analysis from the first seven U.S. cases found that the virus was a never-before-seen hybrid of North American and Eurasian swine flu, a North American bird flu and a North American human flu.
Flu viruses mutate easily. Small genetic changes can "tune" a strain to its new host if a virus jumps species. The result can be a strain that is more easily transmitted -- and in some cases, more virulent -- than when it first arrived. The mutations, however, can occur only if the virus is spreading and replicating, which is why stopping chains of transmission early is so important.
The CDC had dispatched investigators to California and planned to send a team to Texas to help officials identify cases and trace their contacts. Officials urged doctors to be on alert for more cases. The CDC had also taken preliminary steps to create a vaccine for the virus.
"We do not know whether this swine flu virus or some other influenza virus will lead to the next pandemic. However, scientists around the world continue to monitor the virus and take its threat seriously," Richard E. Besser, acting director of the CDC, said in a telephone briefing. He also confirmed the eighth U.S. case -- a child in San Diego County who recovered.
The CDC issued an "outbreak notice" alerting U.S. citizens traveling to Mexico and recommending that they take steps to protect themselves, such as washing their hands frequently. The government has not warned people against going there, but officials said the public should be vigilant.
"I think it's very important people pay attention to what's going on. The situation has been developing quickly," Besser said. "This is something we are worried about and we are treating very seriously."
In both countries, the virus has tended initially to cause typical flu symptoms, including runny nose, cough, fever and sore throat. But in Mexico, the infection is frequently progressing to severe pneumonia, requiring hospitalization. Experts are puzzled about why the disease has caused relatively mild sickness in the United States, where only one patient has been hospitalized and none have died, and severe illness in Mexico.
"That is part of the unanswered questions," the WHO's Setiogi said.
Besser noted that other respiratory viruses are circulating in Mexico and that it remains unclear how many cases and deaths were caused by the swine flu.
"Sorting out what is caused potentially by the swine flu virus and what could be caused by co-infection -- those are important public health questions," he said.
The virus is resistant to two older drugs designed to fight flu, but two more recent medications, including Tamiflu, seem to be effective.
Most of the cases and 59 of the deaths were in Mexico City, but at least three deaths occurred in the central Mexican town of San Luis Potosi and at least four cases were reported on the Baja peninsula, Setiogi said.
There was no indication that the victims had contact with pigs. In the United States, a father and daughter and two boys who attended the same school were infected, leading officials to conclude that the virus was spreading from person to person.
In Mexico City, news of the outbreak and steps to contain it prompted widespread concern, even though officials reassured residents that they had adequate medical supplies. Movie theaters voluntarily closed.
"We are very angry because of this," said Elessia Galindo, 44, whose 10-year-old daughter's school classes were canceled. "I could not go to work because my kids didn't have school today, and who is going to stay with them? I will have a problem for this at my job. Now the government will use the vaccines for the doctors and what about us? This just shows the bad planning of our bad government."
Staff writer William Booth in Miami and special correspondent Gabi Martinez in Mexico contributed to this report.