SILVA JARDIM, Brazil (AP) \u2014 In a small lab nestled in Brazil\u2019s Atlantic Forest, researchers with gloved hands and masked faces cradle four tiny golden monkeys so a veterinarian can delicately slide a needle under the thin skin of each sedated animal\u2019s belly.<\/p>\n
The next morning, biologist Andr\u00e9ia Martins brings them to the precise spot where they were caught. She opens the wire cages and the monkeys dart out, hopping to a tree or the ground, ascending the canopy and regrouping as a family. They chatter noisily as they vanish into the rainforest.<\/p>\n
This brief, strange encounter with humanity has been for the sake of their own health \u2013 and the survival of their kind. These endangered wild monkeys, called golden lion tamarins, have now been vaccinated against yellow fever, part of a pathbreaking campaign to save a threatened species.<\/p>\n
\u201cVaccinating wild animals for the sake of animals, not to protect humans, is novel,\u201d said Lu\u00eds Paulo Ferraz, president of the nonprofit Golden Lion Tamarin Association.<\/p>\n
When yellow fever began to spread in Brazil in 2016, resulting in more than 2,000 human infections and around 750 deaths, it also quickly killed a third of the highly vulnerable tamarins, the majority of them in just a few months. So scientists in Brazil customized a yellow fever vaccine for the endangered monkeys.<\/p>\n
The inoculation campaign started in 2021, and already more than 300 tamarins have been vaccinated. The first such effort in Brazil \u2014 and one of the first worldwide \u2014 it raises vital questions about how far to go to save a species from extinction.<\/p>\n
One of the traditional adages of conservation is \u201cLeave it be.\u201d But in an age when every corner of the globe is touched by human influence \u2013 from melting icebergs to fragmented forests to plastic-filled oceans \u2013 a new generation of scientists and environmentalists is increasingly calling for more interventionist approaches to save wild animals and ecosystems.<\/p>\n
\u201cThere are people who say we shouldn\u2019t touch nature, that we shouldn\u2019t alter anything. But really, there are no pristine natural habitats left,\u201d said Tony Goldberg, a disease ecologist and veterinarian at the University of Wisconsin-Madison, who supports vaccinating wildlife when it\u2019s safe and practical. \u201cPeople are waking up to the magnitude of the problem and realizing they have to do something.\u201d<\/p>\n
Carlos R. Ruiz-Miranda, a conservation biologist at State University of Northern Rio de Janeiro, is among the scientists who have worked for more than three decades to protect the golden lion tamarins, twice going to their rescue when extinction threatened. He says the vaccinations are the only option left: \u201cIs it too extreme? Give me another alternative.\u201d<\/p>\n
\u201cWe have to intervene when it\u2019s a human-borne conservation risk, if you\u2019re going to have an environment with wildlife,\u201d said Ruiz-Miranda.<\/p>\n
Viruses have always abounded in nature. But humans have drastically changed the conditions and impacts of how they spread in wildlife. Epidemics can travel across oceans and borders faster than ever, and species already diminished by habitat loss and other threats are more at risk of being wiped out by outbreaks.<\/p>\n
\u201cHuman activity is absolutely accelerating disease spread in non-human populations,\u201d said Jeff Sebo, an environmental researcher at New York University, who was not involved in the Brazil project.<\/p>\n
But there are risks. It\u2019s tough to decide which species get the attention and resources needed for survival. In Brazil, a political climate of anxiety about the COVID-19 pandemic and misinformation about vaccines in general has caused delays. Yet if the scientists get it right, they could be pioneers to show what\u2019s possible to save threatened wildlife.<\/p>\n
___<\/p>\n
The story of the golden lion tamarins is an epic saga \u2013 one that Marcos da Silva Freire, a longtime Brazilian health official, has experienced firsthand.<\/p>\n
When Freire was a child in the 1960s, he spent weekends at his family\u2019s property in the Atlantic Forest. But he never saw golden lion tamarins.<\/p>\n
Around that time, Brazilian primatologist Adelmar Faria Coimbra-Filho first raised alarms about the shrinking population of the tamarins. Habitat loss and poaching for the pet trade had reduced their numbers to as low as 200 in the wild.<\/p>\n
Southeastern Brazil was once covered by the rainforest, but today the undulating landscape is an uneven checkerboard of dark green jungle and grassy cow pastures \u2013 only 12% of this rainforest remains.<\/p>\n
Yet it\u2019s the only place in the world that wild golden lion tamarins live.<\/p>\n
The effort to save the charismatic monkeys \u2013 famous for their copper-colored fur and small inquisitive faces framed by silken manes \u2013 led to a pioneering captive breeding program, coordinated among around 150 zoos worldwide, including the Smithsonian National Zoo in Washington, D.C. Many of those animals were then carefully released in Brazil starting in 1984, in cooperation with local landowners.<\/p>\n
When Freire\u2019s father, a landowner, was approached by researchers, he told them to coordinate with his son, then a veterinary student in his mid-20s.<\/p>\n
On a clear July morning, Freire walks along a dirt road on his property, shafts of light splintering through palm fronds. \u201cThe first monkeys were released near here, behind that hill,\u201d he said, pointing from the shore of a small lake, recalling the afternoon nearly 40 years ago.<\/p>\n
He smiled when he saw some of their descendants, two monkeys scampering along a swaying vine. They jumped to a high branch, and soon vanished into a kaleidoscope of green.<\/p>\n
Reintroduction was a learning process, for both the scientists and the monkeys, he recalled. Usually it was the second generation, not the first, that learned to be successful again in the wild.<\/p>\n
Thanks to that effort \u2013 and subsequent campaigns to replant and connect parcels of rainforest \u2013 the population of tamarins slowly recovered, reaching around 3,700 by 2014.<\/p>\n
But any celebration was premature.<\/p>\n
___<\/p>\n
One misty winter morning, Andr\u00e9ia Martins pulled on a camouflage jacket, rubber boots and a face mask, and tucked her machete into her belt. She followed a narrow path through the rainforest, stopping periodically to whistle in imitation of monkey contact calls.<\/p>\n
Martins has been tracking golden lion tamarins in the rainforest for nearly forty years. The longtime biologist for the Golden Lion Tamarin Association can spot the tiny shimmer of golden fur among a green canopy and recognize more than 18 distinct vocalizations \u2013 from the specific calls of alpha males to their mates, to varying sounds to alert young monkeys to different types of food and predators.<\/p>\n
On this trek, she recorded the noisy encounter between two monkey families, a dozen or so animals chattering loudly to proclaim territory.<\/p>\n
It\u2019s because of her patient fieldwork, recording detailed population data for four decades, that researchers were even able to track how many tamarins were killed by the yellow fever virus when it began circulating.<\/p>\n
After the first lab-confirmed death of a tamarin from yellow fever in 2018, her team\u2019s census revealed the population of wild tamarins had dropped from 3,700 to around 2,500.<\/p>\n
Inside the Po\u00e7o das Antas Biological Reserve, one of the largest tracts of continuous forest they inhabit, the death toll was even steeper: A population of around 400 tamarins dropped to just 32. \u201cThey just weren\u2019t there anymore,\u201d she recalled.<\/p>\n
The tamarins had fallen victim again to human encroachment. From the top of a wooden watchtower, it\u2019s possible to see swathes of replanted rainforest, as well as the newly expanded BR101 highway bringing a steady stream of traffic into the region.<\/p>\n
\u201cThis epidemic moved very quickly from north to south, across the country \u2013 no wildlife does that,\u201d said Ruiz-Miranda. \u201cIt\u2019s people. They cross vast distances in buses, trains, planes. They bring the disease with them.\u201d Yellow fever is transmitted by mosquitoes, he explained, but highly mobile infected people spread the disease much farther and faster than insects alone.<\/p>\n
\u201cWe lost 32% of the wild population. It was a tragedy \u2013 it showed us how vulnerable this small population is,\u201d said Ferraz, of the nonprofit Golden Lion Tamarin Association.<\/p>\n
\u201cWe realized that in five years, we could lose the entire population if we did nothing.\u201d<\/p>\n
___<\/p>\n
By a twist of fate, Marcos da Silva Freire had gone on to specialize in viruses. At the time of the yellow fever outbreak, he was a deputy director of technological development at Brazil\u2019s Oswaldo Cruz Foundation, which oversees vaccine diagnostics and production in the country.<\/p>\n
Conservationists who had toiled for decades to protect the monkeys were sharply divided over whether to vaccinate them. Some were hopeful the virus wouldn\u2019t impact the monkeys; others worried that any kind of novel intervention would be too risky.<\/p>\n
But Freire decided to test an idea. He arranged with the Primate Center of Rio de Janeiro to begin trials of different doses of yellow fever vaccines on about 60 monkeys, close relatives of the tamarins, in January 2018.<\/p>\n
A year later, he checked the level of antibodies in their blood \u2013 the vaccine appeared to work, without negative side effects.<\/p>\n
Freire started to draw up a plan for the tamarins. \u201cThe idea is to vaccinate 500 animals,\u201d he said. \u201cFor 150 animals, the goal is to vaccinate, then collect blood samples later \u2013 to test the safety and efficacy.\u201d<\/p>\n
The biologists had already honed a technique for luring the wild monkeys into baited cages. “It sounds like a cliche, but monkeys eat bananas,” said the scientist Ruiz-Miranda.<\/p>\n
But seeking official permissions for something that had no precedent in Brazil, vaccinating a wild species, was not a simple process. And then COVID-19 hit.<\/p>\n
When the team finally got government approval to begin vaccinating wild monkeys, Freire supervised the first rounds of shots.<\/p>\n
So far, they\u2019ve vaccinated more than 300 tamarins and detected no adverse side effects. When they\u2019ve caught and retested monkeys, 90% to 95% have shown immunity — similar to the efficacy of human vaccines.<\/p>\n
The outbreak appears to have subsided, and the monitored monkey population has stabilized overall and even increased a little inside the Po\u00e7o das Antas Biological Reserve. And now the golden lion tamarins have a better shot at surviving as symbols of the Atlantic Forest.<\/p>\n
___<\/p>\n
While authorities elsewhere have inoculated animals to safeguard human health \u2013 vaccinating feral dogs and wild animals such as raccoons for rabies and other diseases \u2013 it\u2019s still very rare for scientists to administer vaccine injections to directly protect an endangered species.<\/p>\n
There was the campaign to vaccinate endangered Hawaiian monk seals against a strain of morbillivirus, launched in 2016. And rabies vaccines have been administered orally, hidden in food, to the endangered Ethiopian wolf and a few other species.<\/p>\n
Martin Gilbert, a wildlife veterinarian and epidemiologist at Cornell University, has studied another potential vaccination campaign by modeling the number of Amur tigers in Russia that would need to be inoculated to provide protection against canine distemper. \u201cInfectious diseases are presenting a conservation threat to wild species, and these are only going to increase as populations become more fragmented and isolated,\u201d he said.<\/p>\n
Of special concern are cases when encounters between humans or domestic animals and wildlife directly pass diseases to threatened species, as with respiratory diseases and great apes. Several studies have shown that chimpanzees that live near human settlements have higher rates of multiple diseases.<\/p>\n
\u201cThere\u2019s a great debate now about whether it\u2019s a ticking time bomb before wild great ape populations get infected with COVID, and it sweeps through groups and kills many apes,\u201d said the University of Wisconsin-Madison\u2019s Goldberg.<\/p>\n
Still, other scientists urge caution for any kind of new intervention.<\/p>\n
\u201cWhat are the unintended consequences of vaccination? You can\u2019t always be certain,\u201d said Jacob Negrey, a biologist and primatologist at Wake Forest University\u2019s School of Medicine. \u201cThat would be my major hesitation \u2013 have we adequately controlled for every last variable?\u201d<\/p>\n
James Dietz, a biologist and president of the U.S.-based nonprofit Save the Golden Lion Tamarins, was initially wary of the vaccination campaign in Brazil. \u201cWhen we choose to vaccinate wild animals against a disease, we may be giving them an advantage over non-vaccinated animals \u2013 and by doing that, we are acting potentially against natural selection that would, over time, be acting to improve the genetics of the species,\u201d he said.<\/p>\n
But in the end, he overcame those hesitations. \u201cIt was only when I realized the scope of mortality that I realized we had to do this,\u201d he said. \u201cAnd I\u2019m very happy with the direction we took.\u201d<\/p>\n
There are other reasons to be cautious. While golden lion tamarins are tiny \u2013 weighing less than 2 pounds \u2013 and can be lured into cages with banana bait, it\u2019s harder with large carnivores. \u201cIt\u2019s exceedingly difficult to capture wild tigers and provide a vaccine,\u201d said Dale Miquelle, who leads the global tiger program at nonprofit Wildlife Conservation Society.<\/p>\n
Still, his organization recommends that \u201cfor small and highly vulnerable populations, it\u2019s a good idea to do vaccinations\u201d against canine distemper. No one has tried yet.<\/p>\n
In Australia, scientists have applied for permits to begin a field trial of vaccinating wild koalas against chlamydia, which infects up to 80% of animals in some populations, causing death and lowering fertility.<\/p>\n
The potential downside? \u201cCatching koalas is really stressful on the animals,\u201d said Samuel Phillips, a biologist at Australia\u2019s University of the Sunshine Coast. \u201cIt\u2019s a fine juggling act between causing stress on them and trying to help.\u201d<\/p>\n
But increasingly, he and other scientists feel that through habitat loss and other environmental changes, \u201cWe have decreased their population so much that it\u2019s already at a critical point.\u201d<\/p>\n
His conclusion: \u201cWe need to do more to help them survive.\u201d<\/p>\n
___<\/p>\n
Follow Christina Larson on Twitter at @larsonchristina<\/p>\n
___<\/p>\n
The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute\u2019s Science and Educational Media Group. The AP is solely responsible for all content.<\/p>\n<\/p><\/div>\n