Scientists in South Africa say they have identified an outbreak of rabies in seals that is believed to be the first time the virus has spread in sea mammals.

At least 24 Cape fur seals that were found dead or euthanized in various locations on South Africa’s west and south coast had rabies, state veterinarian Dr. Lesley van Helden said.

Rabies, which affects mammals and can be passed to people, is almost always fatal once symptoms appear. Rabies spreads via saliva, usually through bites but also sometimes when animals lick and groom each other.