Sánchez-Vizcaíno Tells How Spain Stopped African Swine Fever

Dr. Jose Sánchez-Vizcaíno, DVM, of Madrid, Spain, is known for eradicating the world’s largest and most misunderstood virus – African swine fever (ASF) – from Spain.
( Jose Sánchez-Vizcaíno )

It’s no surprise that Jose Sánchez-Vizcaíno took an interest in vaccines at a young age. When he read his first book about Louis Pasteur at age 7, he was hooked. After all, the word vaccine was tossed around a lot in his home growing up. When he was 2 years old, he was struck with the polio virus – at a time when no vaccines were available in Europe.  

“I did not understand exactly what a vaccine was when I was a kid, but I detected that it was something very special,” Sánchez-Vizcaíno says. 

The polio virus may have left him with limited mobility for the rest of his life, but it didn’t prevent his desire to discover new things and adventure to new places. In fact, after reading about Pasteur, Sánchez-Vizcaíno decided he would find out what all the fuss was about and study viruses and vaccines.

Today, Dr. Sánchez-Vizcaíno, DVM, of Madrid, Spain, is known for eradicating the world’s largest and most misunderstood virus – African swine fever (ASF) – from Spain. If anything, his colleagues say his condition paired with his genuine optimism, prepared him to overcome the worst challenges posed by ASF.

“ASF is an underestimated disease,” Sánchez-Vizcaíno says. “It’s very resistant and can go everywhere. Studying ASF over the years has taught me that the same disease can have different faces. It is very important to understand the different epidemiological scenarios of the disease in order to be able to eradicate it.”


A Look Back at ASF in Spain
Once upon a time, ASF was confined to Africa. However, in the late 1950s, it appeared in Portugal from Angola. Then, it began its slow creep across Europe, reaching Spain in 1960 before moving on to France, Italy, Belgium and the Netherlands. Meanwhile, between 1978-1980, it also appeared in Brazil, Cuba, The Dominican Republic and Haiti. 

In 1960, when ASF appeared in Spain, it spread within what was essentially an undeveloped sector. During the 1960s, as the Spanish economy began to take off, pig production changed. In just a few years, Spain went from family-type holdings to an industrial organization characterized by intensive swine production systems, the incorporation of European breeds, and the use of new handling techniques, Sánchez-Vizcaíno says.

Pig production, which until then had been located mainly in the south and southwest and operated as outdoor production systems, moved to industrial farms that were focused in six regions and resulted in the extensive movement of livestock within the Spanish territory. 

In 1960, the virus spread widely in certain areas of the country. Initially, the usual picture of ASF was acute clinical signs and high mortality. This changed through the years to an endemic disease characterised by mild to subclinical forms and a mortality rate below 5% in infected herds. Thereafter, confirmation of the disease by laboratory diagnosis was required. 

Spain marked the first location where ticks were documented as being associated with the disease spread. Ornithodoros erraticus, a species of soft tick found in certain southwestern areas where the disease was endemic and where the outdoor production of Iberian pigs was located, were discovered to be carriers of the ASF virus.

When ASF entered the wild boar population in Spain, it became a major concern as contact among wild boars and domestic pigs is high. In some places, the wild boar population in Europe is over 700%, Sánchez-Vizcaíno says. 
 

The Road to Eradication
The process to eradicate ASF in Spain was not easy.

Because there is no vaccine for ASF, the Spanish eradication program from 1985 to 1995 was based on the detection of ASF-infected animals by laboratory diagnosis and the enforcement of strict sanitary measures. Researchers combined epidemiological and laboratory techniques with predictive models and early detection techniques. 

“We had to find new diagnostic tools for the detection of positive and carrier animals on a large-scale level,” he says. 

In 1979, his team developed the ELISA test for ASF antibodies detection. He says his proudest contribution to the ASF eradication effort was developing this test and establishing it with a national diagnosis network. 

“ELISA worked great to detect carriers and positive animals because it was sensitive and specific,” he says. “ELISA was very important for the eradication process. We eventually adapted another ELISA test to detect the soft ticks that played a critical role in the spread of ASF in outdoor production facilities in Spain.” 

After 35 years of working to eradicate this disease, Spain was finally declared ASF-free in 1995. Eradicating a disease in an endemic area is not easy, Sánchez-Vizcaíno says. 

“I learned that each epidemiological scenario is different with ASF,” he says. “For example, controlling the disease in large operations with high biosecurity is much different than controlling the disease in backyard farms.”


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Although the virus is always the same, the disease does not always present itself in the same way. 

“There is no single prescription to control or eradicate a disease,” he adds. “During this process, we couldn’t think about the disease alone.”

He says they had to take into account the social, cultural and historical factors involved, especially in endemic areas. Perception of the disease was a critical hurdle to overcome.

“Everybody was adapted to live with the disease and was used to it,” he says. “They always asked me, ‘After so many years, why do we have to eradicate now?’ I learned that you have to motivate people by showing the advantages of eradication and proving that it is possible.” 

Sánchez-Vizcaíno’s relentless pursuit of ASF answers and application of the latest research methods to advance ASF control and eradication has made a huge mark on the swine industry, says Montserrat Torremorell, DVM, associate professor at the University of Minnesota College of Veterinary Medicine. She first met Sánchez-Vizcaíno when she was a veterinary student in Spain.

“His experience eradicating ASF from Spain gave him a leading advantage at a time when almost nobody in Europe (or almost worldwide) was pursuing ASF as the area of research,” Torremorell says. “He led a high biosecurity research lab (BSL-3) where they were able to conduct research on ASF. That research helped educate control and eradication efforts and advanced vaccine development.”
 

The Fight’s Not Over
As ASF spreads across Europe and Asia, there is no question that the pursuit continues to stop this disease from impacting the global swine herd. 

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Comments
Submitted by CHAO YANG on Mon, 08/26/2019 - 05:08

Is there a vaccine to control African swine fever?