12 February 2023
Animal experts in Brazil are treating endangered wild monkeys with a vaccine against yellow fever. The disease is severely threatening the golden lion tamarin population.
The little monkeys live in the rainforest of southeastern Brazil. They weigh about one kilogram.
Yellow fever began to spread in Brazil in 2016. More than 2,000 people got sick, and 750 died.
Monkeys got sick, too. The disease killed about one-third of the golden lion tamarin population. And, the population was small even before the outbreak. So, scientists created a vaccine to protect the monkeys.
The vaccination campaign began last year. So far, about 300 animals have gotten shots and are reported to be doing well. But, the treatment represents a change in thinking among supporters of wildlife conservation.
Historically, conservationists have believed that humans should not interfere directly with wildlife. A traditional saying in the world of conservation work is "Leave it be."
Vaccination idea
Vaccinating animals to protect their species from extinction is a new idea, said Luis Paulo Ferraz, President of the Golden Lion Tamarin Association. The non-profit group is working to save the monkeys.
The vaccination effort has raised questions about how far humans should go to save wild animals. Some conservationists now believe humans should use their latest scientific developments to save animals.
They argue that humanity already negatively interferes with animals all over the world by developing in areas where they live. So, if humans have the ability to help animals with a shot, they should do so.
Tony Goldberg is a scientist and animal doctor at the University of Wisconsin-Madison. He believes in vaccinating wild animals when possible.
"There are people who say we shouldn't touch nature, that we shouldn't alter anything. But really, there are no pristine natural habitats left," he said. People are "realizing they have to do something," he added.
Carlos R. Ruiz-Miranda agrees. He is a biologist at the State University of Northern Rio de Janeiro. He has been working to protect the monkeys.
The scientist explained how human movement is mainly responsible for the fast and wide spread of yellow fever.
"This epidemic moved very quickly from north to south, across the country – no wildlife does that," said Ruiz-Miranda. "It's people. They cross vast distances in buses, trains, planes. They bring the disease with them."
"We realized that in five years, we could lose the entire population if we did nothing" said Ferraz, of the Golden Lion Tamarin Association.
Andreia Martins is a biologist for the Golden Lion Tamarin Association. It was only because of her work that people knew how many monkeys died from the recent spread of yellow fever. The first monkey died in 2018, and then the total number of tamarins dropped to 2,500.
At the time of the yellow fever outbreak, Marcos da Silva Freire was a deputy director of technological development at Brazil's Oswaldo Cruz Foundation. It oversees vaccine testing and production in the country.
Freire organized testing of yellow fever vaccines for monkeys with the Primate Center of Rio de Janeiro. The vaccine led to antibodies in the tested monkeys and caused no harm, the scientists found. Freire and his team won government approval to treat wild golden lion tamarins soon after.
So far, about 300 have been vaccinated and are reported to be doing well. Tests show that more than 90 percent of the monkeys have immunity, or resistance to the virus, since vaccination.
The outbreak of yellow fever is no longer a big problem for the monkeys, and their population is starting to come back. But, even with the success of the vaccine program, scientists are still not sure about creating vaccines for other animals.
Jacob Negrey is a biologist who studies monkeys. He works at Wake Forest University's medical school. He wondered about unpredictable effects of such wildlife treatment. He explained that you might create a treatment that helps one kind of animal, but hurts another.
I'm Dan Friedell. And I'm Dorothy Gundy.
Dan Friedell adapted this story for VOA Learning English based on a report by the Associated Press.
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Words in This Story
extinction –n. the situation where a plant or animal has died out completely
negatively –adj. to have a bad effect on something
alter –v. to change something
pristine –adj. perfect or untouched/changed
habitat –n. the place where something lives