4 lemurs die of human herpesvirus, including one that had been used in a 'lemur yoga' class

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, PCR tests like a doctor might use to diagnose a person's infection.

Human herpesvirus infections have been documented in lemurs in the past , albeit rarely, and those reports used laboratory methods other than molecular analysis.

These recent cases highlight the dangers of close contact between animals and humans, scientists say.

"We've evolved these kissing behaviors that have resulted in pretty effective transmissions [of HSV-1] to the point where you look at infection rates of humans and they're very high," study co-author Dr.

Jim Wellehan , a professor at the University of Florida's College of Veterinary Medicine, told Live Science.

But when HSV-1 infects lemurs, the consequences can be far more severe, he emphasized.

Lethal "lemur yoga" In the study, published in July in the Journal of Zoo and Wildlife Medicine , Wellehan and colleagues confirmed HSV-1 infections in two ring-tailed lemurs ( Lemur catta ), one black-and-white ruffed lemur ( Varecia variegata ) and one ruffed-lemur hybrid ( Varecia rubra x Varecia variegata ).

All four lemurs were privately owned.

The problem isn't limited to lemurs.

HSV-1 has previously caused fatal disease in other captive and wild primates, including marmosets , saki monkeys , gibbons and other monkeys.