The first outbreak of African Swine Fever, a highly contagious viral disease, occurred in India earlier this year. Officially confirmed by the Indian authorities on 18 May 2020, the virus has already killed approximately 20,000 domestic pigs in the country and researchers say that a vaccine is still up to three years away. Now, conservationists are worried that it could completely wipe out the entire population of the world’s smallest and rarest pig – the pygmy hog.
Once thought to be extinct, the pygmy hog was rediscovered in 1971 and now has a wild population of over 300 individuals. Thanks to the Pygmy Hog Conservation Programme (PHCP), a project initiated by Durrell in 1995, over 130 hogs have now been reintroduced into several protected areas across the northeastern regional state of Assam. However, this new virus now threatens the very existence of these tiny pigs.
“Pygmy hogs are susceptible to domestic pig diseases,” says Parag Deka, Project Director for the programme. “Our hogs have never been exposed to African Swine Fever, so if it reaches our breeding centres anything could happen – we could lose the entire captive population. We need to keep an eye on the wild hogs too. If this disease reaches wild boars, which is already suspected in some areas, then it may also infect the dwindling population of wild pygmy hogs, currently surviving in just a few small pockets of Assam.”
The Pygmy Hog Conservation Programme, a partnership between Durrell, Aaranyak, IUCN/SSC Wild Pig Specialist Group, Assam Forest Department, India’s Ministry of Environment, Forest and Climate Change, and Ecosystems-India, has been keeping track of African Swine Fever since 2018 when an outbreak was reported in China. Spread primarily through direct contact between pigs or via contaminated meat or materials, the virus has been shown to kill nearly all infected pigs.
“We were worried when it reached Tibet, close to the Indian border,” says Parag. “Then in April, I heard about the large-scale death of pigs in eastern Assam, and later that month the same thing happened at a farm just 10km away from our breeding centre. This was extremely worrying. It was not confirmed as African Swine Fever at the time, but alarm bells were ringing for us and we immediately jumped into action.”
Fortunately, Durrell’s Head of Veterinary Services, Andrew Routh, previously enforced biosecurity measures in the UK when foot-and-mouth disease hit in 2001, so was able to help Parag update their biosecurity plan.
“At our breeding centre in Basistha and pre-release centre in Potasali, we have always operated with a high level of biosecurity to minimise the risk of any domestic pig diseases, for example, regular Swine Fever, infecting the captive pygmy hogs,” says Andrew. “So, with the arrival of African Swine Fever on the scene, we immediately reviewed our existing safety measures and set in place changes to structures and working practices. Thanks to generous funding from The Habitats Trust, we were able to start building permanent decontamination facilities to help us ensure that all 85 captive hogs are kept safe. These additional measures augment our biosecurity and strengthen our resilience in the face of a new threat.”
All members of staff were educated on African Swine Fever and signs of the disease and were instructed to avoid all contact with pigs or pork products. The new measures include movement protocols between zones, security fences, limited vehicle access, and visitors are no longer permitted. “It has not been easy for the team to adjust to all of this – moving carefully between different zones, having to disinfect themselves and the equipment constantly – but we adapted at the start of the COVID-19 lockdown in March and we will continue to do so in order to protect the hogs from this new virus,” says Parag. “Our team is aware of the potentially devastating risks of this disease. Most of the staff have worked here for many years – keeping the hogs safe is their top priority, and like me, they are very concerned about the safety of the animals.”
The threat of African Swine Fever has also meant a change of diet for the hogs. “We are still feeding them grains and fruit but vegetables that grow underground, like sweet potato, are unsafe for the hogs to eat because the virus survives for longer in soil,” says Parag. As well as the hogs’ diet, the team also considered the dried grass, or “thatch”, needed for the enclosures. “As soon as we knew about the virus outbreak, we searched the local markets for thatch that had been collected before the end of last year, to ensure it was safe for the hogs to build their nests with – we bought enough to last a whole year. We now plan to grow our own thatch for the hogs at the Potasali centre.”
As areas affected by the global pandemic start to return to normal, with a COVID-19 vaccine already on the horizon, this is sadly not the case for African Swine Fever. “This virus emerged in 1921, and still, we do not have a vaccine,” says Parag. “It is likely that our new biosecurity routine will become permanent, perhaps even a lifelong practice for us. There is of course still a risk and we may need to rethink our strategy to save the pygmy hog from extinction. But for now, I am hopeful that the new plan we have implemented will keep the captive pygmy hogs safe from this awful disease.”
Huge thanks go to Clarkson Jersey Trust, The Habitats Trust, ZGAP (Zoologischen Gesellschaft für Arten und Populationsschutz), AFdPZ (Association Française des Parcs Zoologiques), DODO Fundacja Zoo Wroclaw, and Beauval Nature for their incredible support towards this project.
Photo credits: Craig Jones (news page image), Udayan Borthakur (header photo), Parag Deka (images 1-3) & S.R. Marak (image 4)
Image 1: a pygmy hog at the pre-release centre in Potasali
Image 2: prohibited entrance at the breeding centre, staff must disinfect before entering the controlled zone
Image 3: an existing building is converted into a permanent shower facility for staff
Image 4: a staff member sanitises bedding materials (thatch) for the pygmy hogs