U.S. Slow to Learn of Mexico Flu
Sunday, April 26, 2009
U.S. public health officials did not know about a growing outbreak of swine flu in Mexico until nearly a week after that country started invoking protective measures, and didn't learn that the deaths were caused by a rare strain of the influenza until after Canadian officials did.
The delayed communication occurred as epidemiologists in Southern California were investigating milder cases of the illness that turned out to be caused by the same strain of swine flu as the one in Mexico.
In the wake of the 2001 terrorist attacks, the outbreak of severe acute respiratory syndrome (SARS) in 2003 and the more recent emergence of H5N1 bird flu in Asia, national and local health authorities have done extensive planning for disease outbreaks that could lead to global epidemics, or pandemics. Open and frequent communication between countries and agencies has been a hallmark of that work.
Whether delayed communication among the countries has had a practical consequence is unknown. However, it seems that U.S. public health officials are still largely in the dark about what's happening in Mexico two weeks after the outbreak was recognized.
Asked at a news conference yesterday whether the number of swine flu cases found daily in Mexico is increasing -- a key determinant in understanding whether an epidemic is spreading -- Anne Schuchat, an interim deputy director of the Centers for Disease Control and Prevention, said, "I do not know the answer to those questions."
As of yesterday, U.S. officials had reported 11 domestic cases, none fatal. Last night, Mexican health officials reported more than 1,300 suspected cases and 81 deaths "probably linked to the virus."
The earliest case found in Mexico was a 39-year-old woman who died April 12 of severe viral pneumonia in San Luis Potosi, a city of about 700,000 in central Mexico.
"That attracted the attention of the epidemiologist there," said Mauricio Hernández, deputy minister for disease prevention and health promotion in Mexico's Federal Department of Health.
The national Health Department surveyed 33 hospitals and uncovered about 120 cases, five fatal, of respiratory illnesses that appeared unusual. Initially, the investigators thought they were seeing an unusually severe outbreak of seasonal flu. Authorities urged hospitals to make sure their workers were vaccinated with this year's flu shot and advised physicians to treat flu cases with the antiviral drug oseltamivir.
On April 16 or 17, Mexico notified the Pan American Health Organization of the outbreak, Hernández said. The organization, based in Washington, is the Americas' branch of the World Health Organization. Spokesmen for both groups were not able to say yesterday when the influenza or pandemic planning offices at WHO's Geneva headquarters learned or were informed of the Mexico outbreak.
In recent years, Mexico has done extensive pandemic planning with Canada and developed a close relationship with the National Microbiology Laboratory in Winnipeg. Tests on virus samples from the Mexican patients suggested the strain was different from this year's flu. So on Monday, Mexican officials sent lung and throat swabs to Canada to be characterized.
The CDC, in Atlanta, is one of WHO's four "reference laboratories" for flu. It routinely gets samples from Mexico and many other countries, and processes them with great urgency, Nancy J. Cox, the head of the flu lab, said last night. It, too, eventually received the Mexican samples.
"The only reason the samples went first to Winnipeg is because the paperwork is easier. We were in a rush," Hernández said.
The samples arrived in Canada on Wednesday. Six hours later, Mexican authorities were told that 16 of 17 had tested positive for swine flu and that it was the same strain just isolated by the CDC from the very different cases in California.
The next day, Mexican health authorities contacted the CDC and the Department of Health and Human Services and said their country's outbreak and the U.S. cases appeared to be two parts of the same event. That same day, the Mexican samples arrived in Atlanta. They were tested in four hours, and Mexico was informed that they pointed to swine flu.