Using genetic studies, scientists are seeking conclusive answers about influenza virus A/H1N1, which continues to mutate.

Surgical masks have become part of the Mexican police uniform. - Marcos Ferro Tarasiuk/IPS

Laboratory tests show that the virus strain initially believed to be swine-based is actually a subtype of influenzavirus A, which contains genetic material from swine, human and avian strains. It easily mutates and recombines, which is what makes it potentially so dangerous.

The microbiology laboratory at Canada's Public Health Agency took a step forward in announcing May 6 that it had decoded the genetic sequence of three samples of A/H1N1 collected in that country and in Mexico.

“This virus already existed. It has been mutating and will continue to mutate. My hypothesis is that we are faced with several subtypes of A/H1N1,” pulmonologist Fernando Cano, former director of Mexico's National Institute of Respiratory Diseases (INER), told Tierramérica.

There have been several documented cases of swine flu in humans, including a non-fatal contagion in 2007 that affected 12 people at a rural fair in the Midwestern U.S. state of Ohio, said Cano, coordinator of the bioethics and clinical medicine faculty sponsored by UNESCO (United Nations Educational, Scientific and Cultural Organization). The people affected by that outbreak were tested and it was found that 60 percent had antibodies to fight that flu strain, added Cano, former director of the medical school at the Autonomous National University of Mexico (UNAM). According to Cano, the virus in Ohio is likely to be an ancestor of the current strain. In a Tierramérica interview, Eduardo Sada, INER head of microbiology research, pointed out reports from 1957 and 1977 on swine flu in humans. “Surely the original virus and the current one circulated in low volume for several years,” until “something that we haven't discovered yet” activated them and created the epidemic, he said.

To assert that this A/H1N1 subtype originated in Mexico at this point is just speculation, agreed Cano and Sada. The virus has now been detected in more than 20 countries.

The first confirmed case of the new virus was in the small, impoverished community of La Gloria, in the southeastern Mexican state of Veracruz. From mid-March to early April, a rare outbreak of flu affected 600 people in the town, located some 10 kilometers from a pig farm.

Medical samples from the sick individuals in La Gloria were sent to laboratories in the United States and Canada. One of them, from a five-year-old boy who presented symptoms on Apr. 1 and who recovered with non-specialized medications, contained the new virus, said a report released on Apr. 23.

The same report, from Canada's National Microbiology Laboratory, in Winnipeg, confirmed that a woman who died of pneumonia on Apr. 13 in the southern Mexican state of Oaxaca, and who apparently had no contact with La Gloria, had also contracted the virus.

But they weren't the only cases. In the western U.S. state of California, bordering Mexico, there were others infected.

In the border city of San Diego, on Mar. 30, a boy fell ill with an “atypical” respiratory illness, but he recovered without any major problems. A similar case occurred shortly after, involving a girl in the nearby town of Imperial.

The U.S. Centers for Disease Control and Prevention (CDC), in the southeastern U.S. city of Atlanta, analyzed samples from both and confirmed the presence of the new A/H1N1.

In 1999, young people and swine died in Malaysia, infected with a strange virus. It was believed to be “Japanese encephalitis”, which is transmitted by mosquitoes that bite humans and pigs.

After several months of research and the slaughter of hundreds of pigs, the scientists discovered that the problem originated at a farm in which some of the animals had eaten fruit remnants that had been contaminated by bats, which are asymptomatic carriers of the virus. Further, it was determined that transmission to humans occurred through pig saliva.

With that information, the authorities were able to stop the spread of the virus, which was dubbed Nipah, although they were not able to eradicate it.

Teams from the World Health Organization (WHO) and researchers from various countries are now on the trail of the new influenza, which some have named “North American” and others “Mexican” flu, but they agree it will be very complicated to determine its place of origin.

Cano, former INER director, believes the deaths caused by A/H1N1, nearly all in Mexico, are related to delays in medical attention or inappropriate treatment, but does not rule out that there could be further infections with variants of this virus strain.

“In any case, the new virus is generally not very lethal, and that is fortunate,” although it should not be forgotten that it could mutate and generate a severe pandemic in the future, he warned.

On Apr. 23, Mexico decreed a health emergency after confirming the presence of the new virus. On Apr. 24, the WHO also declared a public emergency. It then elevated its epidemiological alert from three to four, and later to five (out of six).

On May 4, Mexican authorities announced the stabilization of the epidemic, calling for the gradual reactivation of school and business activities, which had largely been paralyzed since Apr. 23.

Every year, between 250,000 and 500,000 people around the globe die from various types of influenza, known as seasonal because they usually present during the colder times of year, says the WHO.

At first, the appearance of A/H1N1 confused the scientific community, because the strain circulating mostly affected young adults. However, of the more than 1,000 cases confirmed in Mexico, nearly half were people 19 and younger.

Another issue to be clarified is why the people who died from the virus have nearly all been Mexican, and why some of the infected are able to recover without complications or pharmaceutical treatment, while others end up hospitalized.

For now, there are more questions than answers about the traits of the new virus, its origin and its mutation profile, after Canada confirmed that some pigs had contracted the virus from a sick farm worker.

Cano recommended that people continue to get vaccinations against seasonal flu, which even if it does not specifically target the new strain, it does provide additional protection.

The A/H1N1 virus, which is spread in the same way as any other influenza virus, reacts well to antivirals if they are administered in a timely manner, though scientists fear new mutations could mean the pharmaceuticals will be less and less effective.

The first analyses by a multidisciplinary team from UNAM and the National Polytechnic Institute, set up to study the virus, confirmed that it has a great capacity to mutate, said microbiologist Antonio Lazcano, who considers it highly probable that there are different varieties of A/H1N1 circulating in Mexico alongside other flu viruses.