"This study shows the importance of wildlife monitoring as a means of early detection for pathogens that could affect both animals and humans," said Pablo Beldomenico of the Wildlife Conservation Society.
The yellow fever virus originated in Africa and was brought to the Americas by colonists and the slave trade. There is a vaccine for humans, though neotropical primates remain highly susceptible to the disease, Beldomenico and his team wrote in a recent issue of the American Journal of Primatology.
The monkeys died during two yellow fever outbreaks from November 2007 to October 2008, their deaths first noticed by researchers conducting an ecological study of two howler monkey species at El Pinalito Provincial Park.
Argentina's National Health Authority was notified and began a vaccination campaign among humans in the area.