Like a warning call from the
wild, howler monkeys in Argentina alerted health officials to an outbreak of
In November 2007, researchers
found four wild monkeys in a population that they had been studying dead. The
biologists, park rangers, and veterinarians quickly searched both within and
outside of the research area to see if other monkeys were dying as well.
They were. At least 59 howler
monkeys died during the austral springs and summers of 2007-2008 and 2008-2009.
About two months after the first monkeys were found, tests conducted at the
Instituto Nacional de Enfermedades Virales Humanas confirmed the culprit:
Colonists and the slave trade
brought the virus that causes yellow fever to the Americas from Africa. South American primate species did not evolve with the yellow fever virus, and
thus never adapted defenses against the disease. Howler monkeys, along with
all other primates found in the New World, are very vulnerable to yellow fever. This mosquito-born
disease is also deadly to humans.
The primate researchers
notified Argentina’s National Health Authority, which launched a vaccination
campaign for the people of Misiones province for yellow fever. What began as an
ecological study of South American monkeys helped save lives.
“This study shows the
importance of wildlife monitoring as a means of early detection for pathogens
that could affect both animals and humans,” said Dr. Pablo Beldomenico of the
Wildlife Conservation Society.
Because most howlers die
suddenly after becoming infected with the yellow fever virus, a team of
Argentine scientists and WCS health experts concluded that these populations do
not serve as reservoirs for the disease. In other words, when members of these populations
do get sick, they signal to humans that an outbreak is afoot. The researchers
recently published their findings in the American Journal of Primatology.
Other strategies for yellow
fever transmission between humans and wildlife include encouraging people to
report any monkey deaths they encounter, as well as educating those who live
near protected areas of the disease risks of capturing animals for pets.
“The outbreak has tragic
conservation implications for the endangered brown howler monkey, one of the
two species affected,” said added Beldomenico. “This primate is highly
threatened primarily by habitat destruction, hunting, and now disease.”