Depending on the STD, a person may be able to spread the infection if no signs of disease are present. For example, a person is much more likely to spread herpes infection when blisters are present (STD) than when they are absent (STI). However, a person can spread HIV infection (STI) at any time, even if he/she has not developed symptoms of AIDS (STD).
Also her immune system also plays an important role in transmission of STD’s and hygiene after having sexual contact. There are many factors that could influence in her ability to get an STD, I can’t tell you who gave her the STD, any of her sexual partner(s) could have gave her the conditions.
I would suggest both of them to get treated for the particular STD’s and practice safe sex in the future.
These Q&A’s are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.