Four lemurs that had close contact with people, including one via a "lemur yoga" class, caught a human herpesvirus and subsequently died, a new study shows. The virus at fault was herpes simplex virus type 1 (HSV-1), which is extremely common in humans. In people, the infection usually causes no symptoms or produces cold sores. In primates, though, the infections can often be deadly — in this case, all four lemurs developed encephalitis, or inflammation of the brain, and died. This is the first time that an HSV-1 infection has been confirmed in lemurs via a molecular analysis — namely,...