“The pigs are gone”: Swine fever poses fatal threat to food source for millions

Feral pig populations are declining due to the spread of African swine fever (ASF), threatening the livelihoods of millions of people who depend on them for food, researchers warn.

Over the past 10-20 years, ASF has spread to Asia, Europe and Africa with an almost 100% fatality rate, decimating domestic and wild pig populations. Researchers say the impact is particularly significant in Borneo, in Southeast Asia, where bearded pig numbers have fallen by 90-100% since they arrived on the island in 2021.

According to a letter published in the journal Science, these pigs were once the most common species of large mammal on the island, playing an important role as “ecosystem engineers” by dispersing seeds over long distances. “These pigs have disappeared,” said Professor Eric Maillard, lead author of the letter and former chair of the IUCN Wild Pig Specialist Group.

“I’ve been to everyone doing camera traps in Borneo and we keep seeing pigs disappearing. They haven’t seen pigs on camera traps in years,” Meillaard said. The professor also monitored seven camera tracking programs in Malaysia, Indonesia and Brunei, which did not exist on the island of Borneo, and found that their pig numbers fell sharply in 2019 and 2020. “Once ASF enters a population, it wipes out everything,” he said.

Mailyard believes the bearded pig may need to be moved from vulnerable to endangered as a result of African swine fever. Scientists say there is no evidence that wild pig populations will fully recover in Borneo or other Southeast Asian islands such as Java and Sumatra in Indonesia, East Timor and the Philippines.

In Borneo, the disappearance of bearded pigs is already having a huge impact on the cultures and communities that depend on them for food. Local research shows that bearded pigs once accounted for 81% of the total game harvest by weight in some villages. Now this number is closer to zero. “This is a food security issue and a poverty issue. People are simply completely dependent on access to wild pigs to meet their protein needs,” states Meyard.

The disappearance of this key source of protein is putting pressure on other species: in the absence of pigs, millions of local people are likely to turn their attention to hunting endangered species such as pig-tailed macaques, scientists warn.

The loss of feral pigs can also impact the ecosystem as a whole. Bearded pigs disperse tree seeds by eating fruit and migrate long distances, scattering them throughout the forest. They also turn over the soil with their stigmas, which clears the undergrowth and gives tree roots access to more soil nutrients. Borneo’s forests are among the most diverse ecosystems in the world, but only 50% have survived decades of logging and agricultural expansion, especially palm oil plantations.

Scientists have called for urgent research and intervention, while recognizing the implications for communities. The letter recommended an urgent focus on preventing the spread of ASF to other regions.

“Although African swine fever has received significant attention in countries with large pork production, its effects in Borneo have largely gone unnoticed,” the researchers wrote. “Pig deaths undermine food security and ecosystems and threaten other endangered wildlife species.”

Trials to create an effective vaccine have shown positive results, but it would be more effective in domestic pigs. Vaccinating wild pigs would be “extremely complex logistically and expensive to implement,” said Professor Benoit Goossens of Cardiff University, another author of the letter.

James Wood, an epidemiologist at the University of Cambridge who was not involved in the letter, said it raises important questions about the global perception that wild pigs carry disease and therefore pose a threat to the domestic pork industry. He notes: “In contrast, the authors describe how wild pig species, which in Borneo and other islands of Southeast Asia are central to both the culture and diet of many different peoples, are being devastated by the ASF virus, which has spread throughout the world in resulting from the movement of pigs mediated by humans and pig products.

“Every effort must be made to prevent the further spread of ASF between islands in Southeast Asia, particularly through trade in pigs and pig products, as the impacts there could be much worse than just in the pig industry.”

Dr Harriet Bartlett from the University of Oxford, who was not involved in the work, agreed that the disease’s effects were concentrated on the pig industry. “To effectively combat ASF, it is important to broaden our focus beyond immediate economic concerns to include broader environmental and social impacts,” she said.