Saliva helps protect teeth and gums from bacteria that cause cavities and gingivitis. So a perpetually dry mouth is more susceptible to tooth decay and gum disease.

Earlier this year, consumers were close to being able to pick up a saliva-based genetic test for disease risk the next time they ran to the drug store for aspirin or sunscreen.

The disease infects domestic and wild animals, and is spread to people through close contact with infected saliva via bites or scratches.