Puzzling New Flu Strain Causes Concern in Mexico

WHO, CDC, other health agencies take action to understand the never-before-seen A/H1N1 virus

CEO SUMMARY: In recent weeks, health authorities in Mexico became aware of a new strain of influenza, A/H1N1, because of unexpected deaths from “atypical pneumonia.” As early as April 19, the CDC had identified similar cases in Texas and California. By last Friday, WHO, Canada’s PHAC, and the CDC had posted public alerts about this new form of influenza. All clinical lab directors and pathologists should stay current with announcements from the CDC and local public health labs.

LAST FRIDAY, THE NEW STRAIN OF INFLUENZA IDENTIFIED IN MEXICO in recent weeks became headline news. Public health officials describe this new strain as A/H1N1 and say it is a never-before-seen combination of human, pig, and bird strains.

THE DARK REPORT was the first laboratory publication to inform its clients and readers of this fast-breaking news story. A Dark Daily e-briefing was released late Friday afternoon, just hours after the Centers for Disease Control and Prevention (CDC) issued its first public statements about this new strain of influenza, which the media calls “swine flu” because a significant amount of its genetic composition is similar to the known swine flu strains.

To bring laboratory directors and pathologists up to speed on this important story, here are key facts:

Veratect, Inc., of Kirkville, Washington is a company that monitors disease out-breaks on behalf of its clients. It says that it was first to identify that an unknown strain of the influenza virus was likely the cause of a patient death in Vera Cruz, Mexico, on April 6. It reported this finding to several public health organizations, including the CDC.

Between April 6 and April 24, Mexico identified cases of what its health officials described as “atypical pneumonia” and late-season influenza in several states, including Distrito Federal, San Luis Potosí, Baja California, and Oaxaca. Through April 24, Mexico identified 20 deaths from A/H1N1, was investigating another 40 deaths suspected from the same case, and reported 943 cases nationally of this new strain of flu.

Eight Confirmed Cases In U.S.

Also as of Friday, April 24, the CDC reported eight confirmed cases of swine influenza in the United States. Two cases were in San Antonio, Texas, and six cases were in the California counties of Imperial and San Diego. CDC said that preliminary genetic tests identified the cases as swine influenza A/H1N1 and that these cases were genetically similar to cases identified in Mexico. The CDC confirmed some of these cases as early as April 19.

Illnesses in Mexico were reported to be more severe than they were in the United States, where, as yet, no deaths are attributed to this strain of influenza. CDC received 14 specimens from Mexico, and seven were positive for swine influenza A/H1N1.

In Canada, on April 22, the Public Health Agency (PHAC) put quarantine services on alert for travelers returning from Mexico with influenza-like illness (ILI). Public media announcements commenced on that date. The CDC received 51 specimens from Canada and 16 were positive for swine influenza A/H1N1.

So far, the United States has not reported deaths from the new swine flu. Last Friday, the New York Times reported that, of infections identified in the United States, “Five of the people infected were in Imperial and San Diego Counties in California and two were in San Antonio. They were 9 to 54 years old. None had any contact with pigs, and in two sets of cases—involving a father and daughter and two 16-year-old schoolmates—those infected had contact with each other. That convinced the authorities that the virus was being transmitted from person to person. The seven people were apparently infected from late March to mid-April. Only one was hospitalized, and all recovered.”

U.S. Officials Go On Alert

Investigating the outbreak, the CDC sent staff to California, Texas, and Mexico. At border crossings and international ports of entry into the United States, enhanced surveillance was instituted. On Friday, the CDC was collaborating with officials from WHO, Canada, and Mexico, and seeking to characterize the severity of the clinical illness and the viral agent while also developing a communication strategy.

Even as public health authorities are working on a common response, the 24-hour cable news channels have begun showing video clips of how residents of Mexico are responding to news that a new strain of influenza has been identified. There are early signs of widespread consumer concern in Mexico. For example, last Friday, officials in Mexico City and suburbs suspended classes for all students, from nursery school to university level. At least six million students stayed home on that day. A further ban on most public events in Mexico City—including soccer matches—was announced over the weekend.

Informador, a Mexican news bureau, reported Friday that medical students at the San Luis Potosí Autonomous University (UASLP) were staying away from the Central Hospital in that city. The medical students were concerned about the “untypical pneumonia” cases and the risk of infecting their families and friends. There have been four fatal cases in San Louis Potosí.

Containment Not Likely

Privately, experts at WHO and CDC are saying that containment of this outbreak may now be impossible. There are about 1,000 people infected in at least 14 of Mexico’s 32 states. Surveillance efforts by public health officials were only intensified less than a week ago.

It may also be too late to try and contain the spread of this new virus in the United States. One epidemiologist observed that no direct contact is known between the two cases in San Antonio and those cases in the San Diego area. That raises the possibility that the virus was spread between these two regions by other undiagnosed carriers of the virus.

Clinical laboratory managers and pathologists should develop strategies and response protocols to this situation. Close communication with public health agencies and the CDC is also recommended. THE DARK REPORT and sister publication Dark Daily will continue to track unfolding events. Clients and readers are encouraged to contact our editors with useful new information or insights about influenza strain A/H1N1.


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