STIs: What They Are, How They Spread, and Why Nobody Talks About Them Enough
What are STIs, really? A straightforward look at how sexually transmitted infections spread, why they’re so common, and why the silence needs to end.
STIs & Sexual Health · Say Sexology
Spoiler: STIs don’t care about your reputation, your relationship status, or how many partners you’ve had.
Let’s start with the elephant in the room: sexually transmitted infections (STIs) are incredibly common. More common than most people realise, partly because most people who have them don’t know, and partly because we’ve collectively decided this is too embarrassing to discuss.
That’s a problem. Because the less we talk about them, the less people get tested, the less they use protection, and the more infections spread. It’s a perfectly self-reinforcing cycle of embarrassment and ignorance, and it helps no one.
So let’s talk about it. Clearly. Without drama. And with enough information to actually be useful.
What Is an STI?
An STI (sexually transmitted infection) is an infection passed from one person to another through sexual contact. The older term was STD (sexually transmitteddisease), but “infection” is now preferred, because many STIs don’t cause symptoms or disease for a long time, or ever. You can have an infection without being “ill” in the conventional sense.
STIs are caused by:
- Bacteria: such as chlamydia, gonorrhea, and syphilis. These can usually be cured with antibiotics.
- Viruses: such as HIV, herpes (HSV), HPV, and hepatitis B. Viruses can be managed but not always cured.
- Parasites: such as pubic lice (“crabs”) and trichomoniasis. These are treatable.
The distinction between bacterial and viral STIs matters for treatment: bacterial infections can often be fully cleared with the right antibiotic. Viral infections stay in the body: some manageable (herpes), some effectively controlled with medication (HIV), some cleared by the immune system over time (many HPV strains).
How Do STIs Spread?
Different STIs spread in different ways, which is why understanding the specific transmission routes matters for protection.
Through bodily fluids
HIV, gonorrhea, chlamydia, hepatitis B, and others spread via blood, semen, vaginal fluids, and breast milk. This includes vaginal, anal, and oral sex.
Through skin-to-skin contact
Herpes (HSV-1 and HSV-2) and HPV can spread through direct skin contact with an infected area, even without visible sores or symptoms. This is why condoms, while protective, don’t eliminate transmission risk entirely for these infections.
Through blood
HIV and hepatitis B and C can be transmitted through shared needles or blood transfusions, not just through sex.
Important:
You cannot get an STI from a toilet seat, a swimming pool, sharing cutlery, or a hug. STIs require specific transmission routes. Social contact is not one of them.
The Invisible Problem: Asymptomatic Infections
This is the single most important thing to understand about STIs:most people who have one don’t know they have it.
Chlamydia (one of the most common bacterial STIs globally) is asymptomatic in up to 70% of women and 50% of men. Gonorrhea often produces no symptoms in women. Herpes can be transmitted even when there are no visible sores. HIV can remain undetected for years without testing.
This isn’t a reason to panic. Itisa reason to get tested regularly if you’re sexually active, not because you suspect something is wrong, but because that’s just good maintenance, like servicing a car you actually want to keep running.
Waiting for symptoms before getting tested is a bit like waiting for a warning light before checking the engine oil. By then, the damage may already be done.
️ How Do You Protect Yourself?
No method offers 100% protection, but combining methods brings you very close.
Condoms: the multi-taskers
External and internal condoms, used correctly and consistently, significantly reduce the risk of most STIs. They’re not perfect for skin-to-skin infections (herpes, HPV) because they don’t cover all potentially infected skin, but they’re the most effective barrier tool available and should be the default for casual sex.
Dental dams: for oral sex
A thin sheet of latex used during oral sex on a vulva or anus. Less commonly used than they should be, but worth knowing about. An unrolled condom cut lengthways works as a substitute.
PrEP: for HIV specifically
Pre-Exposure Prophylaxis (PrEP) is a medication taken by HIV-negative people that dramatically reduces the risk of contracting HIV. When taken correctly, it’s over 99% effective. Available in many countries, check with your healthcare provider or sexual health clinic.
Vaccination
Vaccines exist for HPV and hepatitis B: two viral infections that can have serious long-term consequences (HPV is the leading cause of cervical cancer; hepatitis B can cause liver disease). If you haven’t been vaccinated, talk to your doctor.
Regular testing and open communication
Testing regularly means catching infections early, when they’re easier to treat and before they’re passed on. Talking openly with partners about STI status, testing history, and protection preferences is awkward exactly once. After that, it becomes normal.
The Numbers (Because They Matter)
According to the World Health Organization:
- More than1 million STIsare acquired every day worldwide.
- Each year, approximately374 millionnew infections occur from just four curable STIs: chlamydia, gonorrhea, syphilis, and trichomoniasis.
- Over500 millionpeople globally have genital herpes (HSV-2).
- More than290 millionwomen have HPV.
- An estimated39 millionpeople are living with HIV worldwide.
These aren’t numbers that belong to some other demographic. They’re the numbers of ordinary people, in ordinary relationships, who didn’t get tested, didn’t use protection, or simply didn’t know.
The Stigma Problem
One of the biggest obstacles to STI prevention and treatment isn’t medical: it’s social. The stigma around STIs leads people to avoid testing (because knowing feels worse than not knowing), avoid telling partners (because shame wins over responsibility), and avoid seeking treatment (because the conversation with a doctor feels unbearable).
This stigma is both irrational and harmful. Getting an STI doesn’t say anything about your character, your morality, or your worth as a person. It says that you had sex and were exposed to a pathogen, which is a biological event, not a moral one.
The only truly responsible position is to test, treat, and communicate. That’s it. Everything else is noise.
Quick Action List
- Get tested regularly if you’re sexually active (frequency depends on number of partners and types of sex, ask your doctor)
- Use condoms with new or casual partners
- Check your HPV and hepatitis B vaccination status
- If you’re at high risk for HIV, ask about PrEP
- If you test positive for anything: treat it, tell recent partners, and move on without self-judgment
“An STI diagnosis is a medical event, not a moral verdict.”
What healthcare professionals wish more people understood
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