In 2019, Jonah Sacha, a researcher at Oregon Health and Science University, received a delivery of 20 monkeys from Mauritius. As part of his research into stem-cell transplants as an HIV treatment, he performs tests on long-tailed macaques.
The captive-bred monkeys were legally imported using an approved vendor, and looked healthy. However, when Sacha tested them, one appeared to have latent tuberculosis (TB).
None of the monkeys could be used because Sacha needed disease-free animals to produce accurate research. “My feeling was one of utter despair; it set this project back by more than a year and a half,” he says.
The test also threw into question the source of the monkeys. The macaque could have contracted TB from a human while in captivity, or it could mean the monkey came from the wild – where TB is relatively common among macaque populations – and was then mis-sold as captive-bred.
“This is the heart of the matter: we don’t know,” says Sacha. “I’ve heard stories of people saying they received animals they thought were research-bred, then they get them, and they’re clearly not because they have found, for instance, little pellets from a shotgun in the animal. That’s a wild-caught animal.”
The incident sheds light on the murky world of importing monkeys for laboratory research. An international shortage of lab monkeys has driven up prices, incentivising a booming illicit trade. The problem risks undermining research, creating new pandemics, and fuelling wildlife trafficking. As the tradeexpands, a once-thriving species is now on the edge: in 2022, it was added to the IUCN list of endangered species. Some animal rights activists are calling to end the trade altogether.
Long-tailed macaques are the most heavily traded primate species in the world, according to a paper published in September, and much of this is for laboratory research. The US National Association for Biological Research says non-human primates remain a critical resource for research, with about 70,000 monkeys imported a year to study infectious diseases, the brain and the creation of new drugs. Difficulty getting monkeys is compromising important research, Sacha says. Before the pandemic he was paying between $2,000 (£1,600) and $5,000 for an animal. Now, it’s about $20,000. “For a couple of years during lockdown it was near impossible to get them,” he says.
He is not alone. Almost two-thirds of researchers struggled to find monkeys in 2021, according to a report from the US National Academies of Sciences, Engineering, and Medicine, which found that the supply of monkeys for research is at crisis point. According to an article in Science, the report is the “strongest government statement yet on the precarious state of monkey research”. A similar picture is coming from Europe, where a shortage of monkeys has resulted in some research being abandoned.
Long-tailed macaques (the monkey most commonly used in medical research) are protected under international trade law and special permits are required to import the animals into the US.
Laboratories need pathogen-free primates that are in good condition and so do not want monkeys that have been wild-caught. With prices so high, however, traffickers are incentivised to catch them in the wild and launder them in via established breeding colonies.
For decades, China was the largest supplier, but it banned the wild animal trade in 2020 in light of the Covid pandemic. Demand for monkeys increased significantly in the following years, but supply did not. Cambodia has since significantly increased exports to plug the gap and tap into this increasingly lucrative market.
“The price is driving the desire of producers,” says Anne-Lise Chaber, an illegal wildlife trade researcher at the University of Adelaide, in Australia. Chaber’s research, published earlier this year in the journal One Health, says individual monkeys are being sold for between $20,000 and $24,000. Globally, south-east Asia is a large international supplier of macaques, but their breeding and trade has been poorly regulated, which can lead to more wild aminals being caught than is sustainable.
“It’s unlikely Cambodia managed to increase their production in such a short timeframe, so we need to understand how they made it happen,” says Chaber.
The country’s export numbers tripled from 10,000 monkeys in 2018 to 30,000 in 2019 and 2020. Researchers write in the paper that Cambodia “has historically been incapable of producing second-generation offspring macaques, therefore increasing their production capacity legally seems unlikely”.
In November 2022, Cambodia was hit by a smuggling scandal: eight people were charged with illegally importing wild-caught monkeys into the US, falsely labelled as captive-bred. The macaques were taken from national parks and other protected areas in Cambodia to breeding facilities, where they were provided with false export permits, officials alleged. More than 14,000 wild macaques were trapped in this way, the US Justice Department says.
In the past 30 years, the wild population of long-tailed macaques has fallen by 40%, with a further 50% decline predicted over the coming three generations. One reason for the decline is over-utilisation for scientific purposes.
Nadja Ramseyer Krog, director of the Long-Tailed Macaque Project, says there is a misconception that macaques are populous because so many of them now live in cities in south-east Asia: “It’s not a very popular animal, in some areas. They do things like run into hotels, open the fridge and grab a Coca-Cola. If you go to a popular tourist destination you could maybe see 100 monkeys, but the forest behind it could be empty.”
Krog hopes in time we can stop using primates in research. “But of course we need to find alternatives,” she says. “I don’t think any scientists want to use wild-caught animals, or be part of extinguishing a wild animal.”
When monkeys can be taken from the wild or farmed, it increases contact between humans and wildlife, increasing the risk of pathogen transmission.
“Macaque breeders or sellers are housing thousands of animals in tiny crates in close proximity, creating the right conditions for the next pandemic: it is a pathogen bomb,” Chaber says. “The irony is that this production of macaques is mainly aimed at providing animals for biomedical research to create vaccines for current outbreaks.”
Animal rights campaigners want the US government to end the “cruel trade”, saying it poses a significant threat to public health. The National Academies report says investing in non-animal “organ on a chip” technology could reduce overall demand.
It also recommended that the US expand its domestic breeding facilities – which it can then regulate. Sacha says: “We shouldn’t be reliant on external countries for these animals that are really critical to our ability to test new therapeutics and vaccines and medicines.”