One simple kiss transfers 80 million bacteria. Blech...
One kiss 'shares 80 million bugs'
A single 10-second kiss can transfer as many as 80 million bacteria, according to Dutch scientists.
They monitored the kissing behaviour of 21 couples and found
those who kissed nine times a day were most likely to share salivary bugs.
Studies suggest the mouth is home to more than 700 different types of bacteria - but the report reveals some are exchanged more easily than others.
The research is published in the journal Microbiome.
Locked lips
A team from the Netherlands Organisation for Applied Scientific Research (TNO) asked 21 couples a series of questions to assess their kissing habits, including how frequently they had kissed in the last year and when they last locked lips.
Scientists took bacterial samples from the volunteers' tongues and saliva before and after a strictly timed 10-second kiss.
One member of the couple then drank a probiotic drink, containing an easily identifiable mixture of bugs.
On the couple's second kiss, scientists were able to detect the volume of bacteria transferred to the other partner - on average 80 million bacteria in a single 10-second kiss.
But while bacteria in the saliva seemed to change quickly in response to a kiss, bug populations on the tongue remained more stable.