the seven hypotheses on the origin of African swine fever in Spain

Up to five laboratories working with the African swine flu virus (ASF) will be audited to see if one of them could be behind the outbreak among Collserola wild boars. This was announced by the President of the Generalitat, Salvador Illa.

These centers have in common that they are located 20 kilometers from the risk zone. The decision was taken following recommendations from the European Union Reference Laboratory, which will oversee the investigation and review of the protocols in collaboration with national authorities.

This decision comes after learning that the Ministry of Agriculture is keeping open the hypothesis that IRTa-CreSa (Institut de Recerca i Tecnologia Agroalimentàries) could be at the origin of the epidemic. It is a reference center in animal epidemiology which has never had a leak.

Accredited to conduct research under biosafety level 3 conditions, IRTa-CreSa has protocols to prevent and contain the transmission of airborne viruses. It is also currently tackling avian flu (H5N1) which has led to the confinement of poultry.

Contacted by EL ESPAÑOL, IRTa-CreSa did not communicate any modification in its research activity.

The seven hypotheses

Ignacio López-Goñi, professor of microbiology at the University of Navarra, director of the Science Museum of the University of Navarra and broadcaster, compiled in an article on his blog MicroBIO the seven hypotheses currently open on the origin of the epidemic.

The microbiologist and broadcaster also offered an assessment of the probability of each scenario based on his experience and criteria.

Migration of sick wild boars. Although the Collserola population may come into contact with ungulates coming from across the Pyrenees, no cases have been reported in the south of France. There are also no active outbreaks on farms in the rest of Western Europe.

Illegal importation of wild boars. These animals could have been brought from a location with active infections for hunting activities. López-Goñi recalls that the Mossos have no proof of this at the moment. In addition, the wild boar is already very common in Spanish reserves.

Infected by ticks. López-Goñi indicates that ticks of the Ornithodoros genus can be vectors for transmitting the virus through bites from pigs and wild boars. These insects exist in Spain, but there is no indication that they have carried ASF.

Infected by waste. According to the now famous “sandwich theory”, a wild boar was infected by food in which the virus persisted while rummaging in trash cans. “It’s a very likely possibility,” says the microbiologist.

It is based on three documented cases. In 1957, the virus entered from Angola to Portugal by plane because pigs on a farm near an airport ate leftovers from airline meals. In 2007, pigs in Georgia that ate food arrived by ship from Africa contracted it. The same scenario happened in Sardinia in 1978.

Accidental transport. ASF is extremely resistant and survives in frozen pork for up to three years. But even on surfaces and materials, it remains dangerous. It cannot be ruled out that it arrived “attached to the wheels or underside of vehicles”.

laboratory leak. The 3 biosecurity centers apply extremely strict measures, emphasizes López-Goñi. “HASRestricted access, negative pressure of facilities, air filtration, decontamination and disinfection of all equipment, recording of all activities…”.

However, the variant 29 of ASF detected in wild boars “is similar to the virus which circulated in Georgia in 2007”, “the reference strain used in experimental laboratory infections to carry out viral studies or to evaluate the effectiveness of vaccines”.

Sabotage. Given that this is a strain used in experimentation but that the thesis of an accidental leak has not been proven, “we should not exclude an intentional (non-accidental) introduction of the virus.” This is, however, “unlikely”, nuances the professor.