Aitor Nogales González
Senior scientist at the CSIC at the Animal Health Research Centre (CISA), National Institute for Agricultural and Food Research and Technology (INIA)
It is not unusual for a swine flu virus to infect humans. Many cases go undetected because there is no epidemiological surveillance in this regard, while others go unnoticed because they are asymptomatic or because specific tests are not performed. These infections are usually mild or even asymptomatic, or cause symptoms similar to those of common flu, and are not usually transmitted between humans, or do so with very low efficiency.
The virus responsible for the 2009 pandemic, the last influenza pandemic to date, was particularly complex, combining genetic segments from swine, avian and human influenza. Its origin was traced and it was confirmed that the jump to humans came from pigs. However, it was a virus that had been recombining and evolving for years before emerging massively in humans.
In contrast, in the current case, pending final confirmation of the analyses and genetic sequences, the available data suggest that it is one of the swine flu variants circulating today. There is no indication, for now, that we are dealing with a particularly novel virus or one that behaves differently than expected. Therefore, the risk to the human population is considered low or very low.