Sexually transmitted diseases (STDs): what they are, symptoms and prevention

Sexually transmitted diseases (STDs), or sexually transmitted infections (STIs), are infections that spread mainly by direct contagion during sexual activity. They are caused by bacteria, viruses, parasites or fungi that pass from one body to another through contact with the skin and genital mucosa, or with infected bodily fluids (in some diseases including saliva). Many, in the early stage, are completely asymptomatic: this is what makes them insidious and makes early diagnosis essential.

The old name, "venereal" diseases, derives from Venus, the goddess of love in Roman mythology.

Two principles that apply to every STD

• Early diagnosis and treatment: needed both to prevent the disease progressing in the individual and to prevent onward transmission to others
• Always treat the regular partner too, even if asymptomatic, to avoid so-called “ping-pong reinfection”: one partner is cured, then reinfected by the other, and the cycle restarts

The main sexually transmitted diseases

HIV and AIDS

AIDS (Acquired Immunodeficiency Syndrome) is a disease marked by the progressive loss of the body's immune defences, caused by the HIV virus (Human Immunodeficiency Virus). Those affected are more exposed to infections that a healthy body would easily overcome, which can then become severe. The virus is transmitted sexually (semen and vaginal secretions) or through contact with infected blood (needles, syringes, transfusions). HIV does not survive in the external environment: it dies on contact with alcohol, bleach or the temperatures reached in a washing machine.

Chlamydia

Chlamydia is an intracellular parasite transmitted exclusively through sexual contact, with an incubation of one to three weeks. It is one of the most insidious STDs for its effect on fertility:

• In women: highly variable symptoms — recurrent cystitis, urinary complaints, cervicitis and adnexitis — up to closure of the tubes, with resulting sterility
• In men: typically a mild urethritis, with urinary symptoms and discharge from the urethral meatus

Genital warts (HPV)

Commonly known as “cockscombs”, genital warts are lesions caused by the HPV virus (Human Papilloma Virus), sexually transmitted, with an incubation from a few days to several months. They appear as small pinkish growths with a rough surface and can occur anywhere on the genitals: glans and urethra in men, urethra and vagina in women.

Gonorrhoea

Gonorrhoea is a bacterial infection transmitted sexually, with a short incubation (2–10 days). In men it classically presents with a purulent urethritis (yellow-green discharge); in women with a cervicitis. If not adequately treated, it can spread through the entire urogenital tract in both sexes.

Genital herpes

Genital herpes is caused by the Herpes Simplex viruses type 1 (HSV-1) and type 2 (HSV-2), generally sexually transmitted, with a short incubation (3–4 days). It affects the foreskin, glans and shaft in men; the vulva, vagina and cervix in women. The lesions are small blisters that rupture quickly, causing burning and redness. The virus rarely leaves the host: after the primary infection heals, recurrences are possible even months or years later, whenever local defences are lowered.

Genital candidiasis (thrush)

Genital candidiasis is caused by a fungus. In men it produces redness and itching of the glans, with a characteristic whitish coating; in women, whitish discharge, pain during intercourse, itching and burning.

Syphilis

Syphilis is caused by the bacterium Treponema pallidum, transmitted exclusively through sexual contact. It follows a classic three-stage course:

• Primary syphilis: 3–4 weeks after infection, a red weeping nodule appears on the external genitals and becomes a painless ulcer (chancre), often with enlargement of the nearby lymph nodes. The chancre heals even spontaneously in 30–60 days — and this is the trap: the disappearance of the lesion does not mean cure
• Secondary syphilis: after 2–3 months, pale pink patches appear all over the body, neither painful nor itchy, which can also disappear on their own in 1–2 months
• Tertiary syphilis: if the disease is not diagnosed and treated, it can become generalised and lead to serious, potentially fatal consequences

Genital trichomoniasis

Trichomoniasis is caused by a flagellated protozoan, Trichomonas vaginalis, which survives poorly outside the human body. Contagion is chiefly sexual, but can also occur through infected objects (towels, underwear). In men, after 1–3 weeks, a urethritis usually appears, with itching and a clear or milky morning discharge; in women, a vulvovaginitis with frothy discharge, burning and pain during intercourse.

Frequently asked questions about sexually transmitted diseases

Can you have a sexually transmitted disease without symptoms?

Yes, and this is the key point. Many STDs are completely asymptomatic in the early stage: chlamydia may cause minimal symptoms in men, and the syphilis chancre heals on its own, giving the illusion of recovery. The absence of symptoms rules out neither the infection nor the risk of infecting others: after a risky encounter, the only way to know is to be tested.

Why does the partner also need to be treated?

To avoid ping-pong reinfection: if only one partner is treated, the other — even if asymptomatic — can reinfect them at the first intercourse, and the cycle restarts. Treating the regular partner is an integral part of the cure, not an optional extra.

Does the disappearance of symptoms mean cure?

No, and syphilis is the most dangerous example: the initial chancre and the patches of the secondary stage disappear spontaneously, but the disease continues silently and can reach the severe tertiary stage. Cure is confirmed by the doctor through testing, not by the vanishing of the lesion.

Do sexually transmitted diseases only concern women?

No. They affect both sexes, in heterosexual and homosexual relationships alike. Several STDs have significant consequences specifically in men: urethritis, epididymitis, and a role for HPV in penile lesions.

How are sexually transmitted diseases prevented?

Prevention rests on protected intercourse, early diagnosis after risky contact, and treatment of the partner. For some infections there are specific tools to be discussed with the specialist or reference centre. If there is any doubt or symptom, the right course is to see a doctor promptly, without waiting.

Have you had a risky encounter or noticed genital symptoms? Ask Prof. Natali for a consultation or book an appointment at his practices in Florence and Empoli, Italy.

The information on this page is provided for general educational purposes and does not replace a medical examination, which remains the only diagnostic tool for correct and effective treatment.