The drugged macaque lying in the bed of a pick-up truck in Thailand’s Khao Yai national park is an unwitting but potentially crucial sentinel for the next pandemic.
Thai veterinarians are taking vials of blood and swabs from the anaesthetised animal, to be screened for known and new pathogens that could infect people.
“Even though we are dealing with wildlife, our work is for human beings,” says Supaporn Wacharapluesadee, a field virologist based in Bangkok, observing a collection of the samples she will later analyse. “It is a hard battle to win — but we hope to stay one step ahead of the diseases.”
The prone primate is one small part of the stuttering global hunt for “Disease X” — an as yet unknown pathogen that could cause the next pandemic. There is a high chance this microbe will be a zoonosis, or disease that can pass from animals to humans.
The lethal dangers were put into stark focus this week by the worsening US bird flu outbreak, which claimed its first human fatality after spreading to livestock and poultry across the nation.
Zoonotic diseases have high potential to cause pandemics in the future as they have in the past — including, very probably, Covid-19. All seven of the priority known pathogens identified by the international Coalition for Epidemic Preparedness Innovations (Cepi) on its website are zoonotic, including Mers, Ebola and Lassa Fever. Many zoonotic diseases have no vaccines or effective treatments.
The risk of transmission is high in environments such as the popular tourist spot of Khao Yai, where visitors often come close to wild creatures. It is rising due to trends such as human population spread and animal behavioural shifts related to rising global temperatures.
Zoonotic diseases pose a “significant threat to global health security”, says Maria Van Kerkhove, director of the World Health Organization’s department of epidemic and pandemic preparedness and prevention.
“It is estimated that three out of four emerging or re-emerging infectious pathogens are zoonotic,” she says. “Drivers such as climate change can accelerate the risk of spillover of pathogens from animals to humans.”
The zoonotic menace is growing in severity. Even beyond bird flu, the last year alone has seen several high-profile outbreaks. Mpox, the virus formerly known as monkeypox that causes rashes and lesions, spread to more than a dozen countries in Africa. Rwanda suffered an outbreak of Marburg viral disease, a haemorrhagic fever similar to Ebola.
Cepi is working with the WHO to improve international understanding of dangerous microbe “families”, many of which are zoonotic. But Cepi has warned of “dark spaces” in knowledge, particularly in biodiverse countries that lack the resources to do disease monitoring and comprehensive research.
The zoonotic story is emblematic of troubled efforts to prevent another global pandemic, almost five years since the WHO declared the last one.
The millions of deaths and trillions of dollars of economic disruption caused by Covid triggered international moves to prevent a repeat. But a WHO-brokered initiative to agree an international pandemic treaty foundered last year. A new deadline for the accord is set for May 2025, by when President Donald Trump may have resumed efforts to fulfill his long-held goal of pulling the US out of the UN health body.
