The animals may help reveal the causes of brain disease in people and point the way to treatments. But researchers already are calling for new ethical guidelines.

In Mato Grosso, Brazil, capybaras wandered into the building, but they were polite during the incursion.

A team of scientists uploaded videos of the squirrel-like rodents in the wild on the adult-content site OnlyFans to raise money amid government budget cuts.

The types of Ebola and hantavirus worrying officials are very different from the species identified decades ago, raising new questions about how to respond.