They occur most frequently between the ages of 16 and 35 years, with 10% of women getting an infection yearly and more than 40–60% having an infection at some point in their lives.
Javljaju se najčešće u dobi između 16 i 35 godina, s tim da 10% žena obolijeva od infekcija godišnje, a 60% ih ima infekciju u nekom trenutku svog života.