When partner has it
Statistically, young females 15-24 have the highest incidence of stds.
As for an individual, you are most susceptable is when your partner has active infections, and also if you are not healthy your body is not able to fight the infections off once you contracted it. So, always practice cautions. An ounce of precention is worth a pound of cure. Stay safe..Consult your doc..Good luck.