Which of the following is sexually transmitted?

Syphilis is a sexually transmitted infection. It is caused by Treponema pallidum. It spreads by direct contact with an infected person’s sores during sexual activity or direct contact with the sores by kissing.

Filariasis is not sexually transmitted. It is transmitted through mosquito bite. Malaria is not sexually transmitted. It is transmitted through mosquito bite. Cancer is a non-infectious disease.