Sexually transmitted infections (STIs), also referred to as sexually transmitted diseases (STDs), are infections that are commonly spread by sexual activity, especially vaginal intercourse, anal sex and oral sex. [1] [2] The most prevalent STIs may be carried by a significant fraction of the human population.
| STI | Number of people with disease | Notes |
|---|---|---|
| Herpes | 4,000,000,000 [3] | It is estimated that more than two-thirds of the global population has herpes, though it mostly lies dormant. |
| Human papillomavirus infection | 800,000,000 [4] | |
| Chlamydia | 450,000,000 [5] | |
| Hepatitis B | 356,000,000 [6] | Preventable with the Hepatitis B vaccine |
| Gonorrhea | 50,000,000 [5] | Globally, 0.8% (women) and 0.6% (men) have gonorrhea. |
| Syphilis | 45,400,000 [7] | |
| HIV/AIDS | 36,700,000 [8] |