Study warns of risk from feline viruses to wild cats on the palm oil frontier


  • A recently published study has found that wild felines are exposed to viruses common to domestic cats, such as feline coronavirus.
  • Certain species that frequent oil palm plants in Malaysian Borneo, such as the leopard cat and Malay civet, may act as carriers of viruses back into forest areas.
  • These findings are of concern, conservationists say, due to the potential impact on threatened small cat species, such as the endangered flat-headed cat and the vulnerable Sunda clouded leopard.
  • Integration of animal welfare into conservation action and oil palm management plans are potential solutions to mitigate the risks of transmission, the study authors say.

Antibody tests conducted on domestic cats and wild cats in Malaysian Borneo indicate that oil palm plants may act as transmission sites for viruses, according to a new study.

The study, carried out by researchers working with the Health at the Edge Project, which investigates wildlife transmission in forest-agricultural landscapes in Borneo, and published in the journal Transboundary and Emerging Diseasesfound that threatened species of wild cat, such as the flat-headed cat (Prionailurus planiceps) and the Sunda clouded leopard (Neofelis diardi), share viruses common to domestic animals in and around the Lower Kinabatangan Wildlife Reserve in the Malaysian state of Sabah.

domestic cats (Felis catus) are fairly common on some oil palm plantations and act as a form of pest control for oil palm workers, preying on rats. They are often free-ranging and wander close to or into nearby forests. Meanwhile, forest-dwelling wild cats, such as the leopard cat (Prionailurus bengalensis), sometimes enter nearby oil palm plantations to hunt prey. Flat-headed cats are considered wetland specialists, but there is growing evidence indicating they also visit plants in search of frogs and rodents.

As they conducted their study, the researchers netted five leopard cats and two flat-headed cats on or close to the edges of oil palm plants. They also trapped 11 Malay civets (Viverra tangalunga) and two Sunda clouded leopards using cages inside the nearby forest.

Researchers say that species such as the leopard cat and Malay civet that adapt well to disturbed habitats may act as carriers of viruses into nearby forest areas, potentially exposing other species in the process. Image © Health at the Edge Project.

Some of the domestic cats included in the study and trapped wild animals positive for feline coronavirus, feline panleukopenia virus tested, and feline calicivirus antibodies. Only domestic cats tested positive for feline herpesvirus antibodies. Based on these findings, the researchers conclude that circulation of viruses within oil palm plants between domestic and wild carnivores is a possibility, though it’s unclear at this stage in which direction they’re being transmitted. Two leopard cats and one flat-headed cat positive for feline coronavirus antibodies tested. The same flat-headed cat was also positive for feline calicivirus antibodies.

“I think overall the case study is evidence that in some way they are sharing the same place and the same areas,” said study co-author Sergio Guerrero-Sánchez, a postdoctoral fellow at the Center for Applied One Health Research and Policy Advice at the City University of Hong Kong. “They can get in very close contact, not necessarily interacting directly, but using the same spot in a matter of hours or enough for one cat to transmit the disease to another.”

A viral pathway

Certain species adapt better to monoculture oil palm plantations than others, increasing interactions with domestic animals. Leopard cats and Malay civets, for example, are known to frequent these areas. The researchers suggest that in doing so, these species may act as viral carriers as they move back into the forest.

“Most importantly, our findings highlight an underestimated effect of oil palm plantations on the native community of carnivores, through the risk of infectious disease increased transmission from domestic animals due to inter-species interactions and habitat overlap,” the authors write. These viruses could be moving in both directions, said co-author Liesbeth Frias, a postdoctoral fellow at the Asian School of the Environment at Nanyang Technological University in Singapore. But the overall concern, she said, is over the potential impact on endangered species.

A domestic cat caught on a camera trap on the edge of an oil palm plantation. Serological tests found evidence of viruses common to domestic cats in wild felids. Image © Health at the Edge Project.

Of the viruses found, feline coronavirus and feline panleukopenia virus are noted as being of a particular concern. The former can develop into feline infectious peritonitis, which can be fatal. Alongside the flat-headed cat and two leopard cats, two domestic cats tested positive for feline coronavirus antibodies. Feline panleukopenia virus, meanwhile, can be particularly harmful to kittens and young cats: Two clouded leopards, two Malay civets and 12 domestic cats had antibodies for FPLV.

In the physical inspection, [the domestic and wild cats] didn’t show any signs of disease, which is also very tricky, especially in wildlife, because they don’t show the sickness until they are very, very sick,” Guerrero-Sánchez said. “We don’t know if some diseases might be affecting more kittens than adults. We don’t know what’s happening there.”

Based on records of viruses passing to other species, he said that “we need to assume that there is a risk for the population.” Other studies have noted evidence of viral transmission between domestic and feral cats with captive and free-ranging populations of snow leopards, tigers, bobcats and pumas, among others. Free-ranging dogs also pose a risk, as they can spread canine distemper virus: an outbreak in the Serengeti in Tanzania in the 1990s decimated lion populations.

Susan Cheyne, a teaching fellow in biological anthropology at Oxford Brookes University, who was not involved in the study, shared these concerns. “This paper has highlighted a clear threat, but there are many unanswered questions eg, how wild carnivores react to disease/virus infection,” she wrote in an email, noting that reactions can differ between hosts. “However, the precautionary principle should always take precedence: these animals are endangered and already highly threatened thus we should take every effort to minimize the disease risk.”

The flat-headed cat is one of the world’s most threatened cat species. There’s evidence to suggest this wetland specialist has adapted to life on the edge of oil palm plantations, where there is often an abundance of frogs and rats, says Wai-Ming Wong of Panthera. One flat-headed cat tested positive for both feline coronavirus and feline calicivirus antibodies. Image by SFD/IZW/Panthera.

The authors stressed that these findings are based on a small sample size; 27 domestic cats and d wild carnivores were tested in total. That said, Frias said it’s a vital first look into this issue. “Southeast Asia is a hotspot of biodiversity and of pathogens, and outbreaks are bound to happen. But there’s not so much information about wildlife disease,” she said. “I think having this paper out, even though it’s a short communication … gives that baseline data that we were needing and that many other agencies probably also need to some extent.”

Wai-Ming Wong, small cats program director for Panthera, the global wild cat conservation organization, said the study should act as a launch pad for further research. Panthera was among the funders of the study. “I think the threat is potentially significant,” he said. “But there’s a lot more about disease transmission that we need to understand to properly evaluate and answer the questions … the findings definitely warrant further investigation.”

Among those questions are the prevalence of disease within populations and whether these viruses are affecting Borneo’s other small cat, the enigmatic bay cat (Catopuma badia). “[T]he flat-headed cat and bay cat are arguably two of the world’s rarest cat species and they could disappear with a blink of an eye if we don’t address these threats, or even find out more about these threats, the extent of them and how they’re impacting populations,” Wong said.

From baseline to solutions?

While Guerrero-Sánchez and Frias said their findings are concerning these threatened species, they could also lead to opportunities to tackle the problem head-on. Working together with plantation managers and other agencies to develop vaccination and sterilization campaigns for domestic and free-roaming cats could be one approach.

“One thing that I find important is that wildlife disease[s] are not often included in conservation strategies,” Frias said. “So having this baseline data, even if it’s very basic, could really help with conservation efforts, and maybe guide some conservation actions, for example, through wildlife disease risk assessments.”

Five leopard cats netted in oil palm plantations were tested for antibodies. Two tested positive for feline coronavirus. Image © Liesbeth Frias.

Integrating surveys of this kind and broader animal welfare into conservation action and oil palm plantation protocols would, the researchers said, be a positive step to mitigate the threat.

“This study shows that disease transmission does occur in this kind of agricultural human dominated landscapes,” Wong said. “It’s really important, I think, anyway, for agricultural companies who are responsible for this habitat modification to include animal health monitoring in their management plans, much like they’re including high conservation value areas into their plantations that allow animals to move between landscapes .”

Cheyne said that due to the need for both qualified vets and laboratory facilities, such programs would be a considerable challenge to implement. But given the risks of zoonotic disease transmission, it’s nonetheless a “critical aspect to manage and to integrate into plantation management protocols,” she said.

Citations:

Guerrero‐Sánchez, S., Wilson, A., González‐Abarzúa, M., Kunde, M., Goossens, B., Sipangkui, R., & Frias, L. (2022). Serological evidence of exposure of Bornean wild carnivores to feline‐related viruses at the domestic animal–wildlife interface. Transboundary and Emerging Diseases. doi:10.1111/tbed.14549

Wu, Q., Wu, H., He, S., Liu, Y., Chen, Y., Qi, X., … Tian, ​​K. (2022). Feline herpesvirus infection and pathology in captive snow leopard. Scientific Reports, 12(1). doi:10.1038/s41598-022-08994-4

Huang, S., Li, X., Guo, L., You, D., Xie, W., Xu, H., … Wang, Y. (2022). Prevalence of four viruses in captive Siberian tigers from Northeastern China. Transboundary and Emerging Diseases. doi:10.1111/tbed.14475

Bevins, S.N., Carver, S., Boydston, EE, Lyren, LM, Alldredge, M., Logan, KA, … VandeWoude, S. (2012). Three pathogens in sympatric populations of pumas, bobcats, and domestic cats: Implications for infectious disease transmission. PLOS ONE, 7(2), e31403. doi:10.1371/journal.pone.0031403

Kadam, RG, Karikalan, M., Siddappa, CM, Mahendran, K., Srivastava, G., Rajak, K., … Sharma, A. (2022). Molecular and pathological screening of canine distemper virus in Asiatic lions, tigers, leopards, snow leopards, clouded leopards, leopard cats, jungle cats, civet cats, fishing cat, and jaguar of different states, India. Infection, Genetics and Evolution, 98, 105211. doi:10.1016/j.meegid.2022.105211

Guiserix, M., Bahi-Jaber, N., Fouchet, D., Sauvage, F., & Pontier, D. (2007). The canine distemper epidemic in Serengeti: Are lions victims of a new highly virulent canine distemper virus strain, or is pathogen circulation stochasticity to blame? Journal of The Royal Society Interface, 4(17), 1127-1134. doi:10.1098/rsif.2007.0235

Banner: Two Sunda clouded leopards tested positive for the highly contagious feline panleukopenia virus. Listed as vulnerable by the IUCN, there are thought to be around 4,500 of this species left in the wild. Image by Cloudtail the Snow Leopard via Flickr (CC BY-NC-ND 2.0).

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Agriculture, Animals, Biodiversity, Cats, Conservation, Diseases, Endangered Species, Environment, Forestry, Forests, Green, Infectious Wildlife Disease, Mammals, Palm Oil, Plantations, Rainforests, Tropical Forests, Wildlife

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