Scientists believe vaccinating monkeys could be key to preventing the next pandemic.
Experts in South America are concerned about a renewed outbreak of yellow fever, killing a higher proportion of infected people than Covid-19.
It is estimated that 30,000 people worldwide die each year from the virus, which mosquitoes spread between primates and humans.
And scientists fear that as cases surge in Brazil, a deadly outbreak is imminent.
Although yellow fever vaccines are available, only 50 percent of people in large cities have been bumped – presumably due to distrust of officials.
To combat the risk of a fatal outbreak, scientists are now venturing into the jungle to inoculate golden lion tamarins. BBC Future reports.
Carlos Ramon Ruiz-Miranda, a biologist at the state university in northern Rio de Janeiro, said, “If you vaccinate the monkeys, you have fewer people carrying the disease. It’s herd immunity.”
Tragically, the signature tamarins have dramatically reduced their habitat and brought them into closer contact with humans.
This increases the risk for more cases, with the numbers now believed to be the worst in 80 years.
It is estimated that 15 percent of people who develop yellow fever die from the virus. Hundreds of deaths have been reported since 2017.
Symptoms include jaundice, severe fever, and headache. In severe cases, this leads to fatal internal bleeding and liver failure.
Hundreds of monkeys have died of yellow fever in recent years, prompting the urge to vaccinate them.
Captive monkeys are injected into their stomach after sedation to protect them from yellow fever.
Once infected, the virus is active for four to six days – that is, mosquitoes that bite them become infected with the virus and can transmit it to humans.
Ruiz-Miranda said: “In previous outbreaks in southern Brazil, the local government responded to killing the monkeys.
“But the monkeys are our guardians – they’ll show you when yellow fever has arrived.”