For the last several years we have been studying simian arteriviruses, a group of viruses that infect African monkeys and frequently cause fatal disease when they jump species into Asian monkeys. Can these viruses infect humans? We don’t know. One argument against human infections is that if they caused similarly severe disease in humans, we would have noticed this by now. A team led by Adam Bailey when he was a student in my lab just published a study showing that not all simian arterivirus cross-species transmissions cause severe disease, raising the worrisome possibility that subclinical human infections might also occur. Read the paper here: https://www.mdpi.com/1999-4915/10/12/701/htm