Sexually transmitted infections, or STIs, are infections passed from one person to another through sexual contact. The contact is usually vaginal, oral, or anal sex. But sometimes it can be intimate skin-to-skin contact.

These infections can be caused by bacteria, viruses, or parasites. Common examples include chlamydia, gonorrhea, herpes, and HPV. A key thing to understand is that someone can have an STI without knowing it. Many infections don't show symptoms for a long time, if at all. This is a major reason they spread so easily.

The primary way STIs are transmitted is through the exchange of bodily fluids like semen, vaginal fluids, and blood. This happens during unprotected sexual activity.

However, transmission isn't limited to intercourse. Some STIs, like herpes and human papillomavirus (HPV), can spread through direct skin-to-skin contact with an infected area or sore. Others can be transmitted non-sexually. For instance, HIV and hepatitis can spread through shared needles. It's also possible for a pregnant person to pass an STI to their baby during pregnancy, childbirth, or breastfeeding.

STIs are a significant global health concern. Millions of new infections occur every year, affecting people of all ages and backgrounds. The impact goes beyond the individual.

Untreated STIs can lead to serious, long-term health complications. These can include infertility, chronic pain, and an increased risk of certain types of cancer. Having an STI can also make a person more susceptible to contracting other infections, including HIV.

The widespread nature of STIs places a heavy burden on public health systems. Costs for testing, treatment, and managing complications are substantial. This is why awareness, prevention, and open conversation are so critical.

Understanding these basics is the first step toward protecting yourself and others. Let's review what we've covered.