US public not warned that monkeys imported from Cambodia carried deadly pathogens

Documents obtained by People for the Ethical Treatment of Animals (Peta) and seen exclusively by the Guardian, along with a case report by the American Association for Laboratory Animal Science, reveal that there have been six cases of Burkholderia pseudomallei identified in primates imported from Cambodia to the US.

Direct transmission of the disease from animals to humans is rare but can occur. There are about 12 human cases a year in the US, mostly in travelers to Asia or Northern Australia.

However, on 27 July 2022, the same day Peta obtained a response to a freedom of information act request, the CDC issued a warning about the presence of B pseudomallei in the environment in the Mississippi Delta. This is the first time it has been detected in the soil and water in the US and came after two people in the state of Mississippi were diagnosed with melioidosis, one in 2020 and the other in 2022. Neither had traveled, and both were hospitalized but recovered.

Primates who were dead on arrival increased from two in 2017 to 11 in 2021, and monkeys dying in quarantine increased from 29 to 125. Primates who were ill but recovered and released rose by 2,280% from five to 119 in 2021, and overall mortality increased from 31 to 136 over five years.

Long-tailed macaques, natives of south-east Asia, are the most heavily traded primate for use in laboratories and are now endangered in part due to the exploitation by the research industry.

Historically, China exported the majority of macaques to the US but ceased trading during the coronavirus pandemic. This, combined with increased demand from the research industry, has resulted in a rise in wild and farmed monkey exports from Cambodia, Mauritius, Vietnam and resumption in trade from Indonesia, Laos and the Philippines. Trappers in Indonesia were filmed inflicting violence on wild macaques during their capture.

In recent years, the number of macaques exported from Cambodia to the USA has more than tripled from 5,851 in 2018 to 18,870 in 2021. The US is the largest importer of primates in the world and the only country to have legally imported wild macaques since 2014.

Long-tailed macaques are often used in toxicity testing to identify adverse effects of drugs or chemicals. The restrained monkeys are dosed by injection, infusion or a tube forced into their stomach without anesthetic. Dosing can last for months or years with side effects including pain, shaking, vomiting, internal bleeding and death.

Proponents say there would be no production of medicines without animal research. However, the US Food and Drug Administration reports that animal tests have a 92% failure rate predicting the safety or effectiveness of pharmaceuticals in humans.

The CDC has previously said Cambodia suspended its export of primates to the US.