What is the difference between an STI and an STD?

"STI" (sexually transmitted infection) and "STD" (sexually transmitted disease) are often used interchangeably, but "STI" is the preferred term in public health and clinical settings. An infection refers to the presence of a pathogen; a disease implies symptoms. Many STIs are asymptomatic — chlamydia in particular — so "STI" more accurately captures the full spectrum of people who need testing and treatment, including those without symptoms.

Which STIs are curable?

Four STIs are fully curable with current antibiotics: chlamydia (azithromycin or doxycycline), gonorrhoea (ceftriaxone — though resistance is increasing dramatically), syphilis (benzathine penicillin) and trichomoniasis (metronidazole). Four others are viral and currently incurable but manageable: HIV (ART controls infection); herpes simplex (antivirals reduce outbreaks and transmission); HPV (vaccines prevent, immune system usually clears infection; treatments address manifestations); and hepatitis B (antivirals suppress, vaccine prevents).

Why is gonorrhoea becoming untreatable?

Neisseria gonorrhoeae has successively developed resistance to nearly every antibiotic class used against it — sulphonamides, penicillin, tetracycline, fluoroquinolones and now cephalosporins. Extensively drug-resistant (XDR) gonorrhoea — resistant to ceftriaxone (the current last-line treatment) — has been documented in multiple countries. Without new antibiotic development and strict antimicrobial stewardship, gonorrhoea could become untreatable. WHO has placed N. gonorrhoeae on its list of priority pathogens for new antibiotic research.

What is congenital syphilis and how is it prevented?

Congenital syphilis occurs when Treponema pallidum (the syphilis bacterium) crosses the placenta to infect the fetus. It causes stillbirth, neonatal death, premature birth, and devastating disabilities including bone deformity, hearing loss, blindness and neurological damage. Prevention requires: antenatal syphilis testing (at first ANC visit and again at 28 weeks in high-prevalence settings); treatment with benzathine penicillin — safe, cheap and highly effective. Despite these interventions being available, over 300,000 congenital syphilis cases occur annually, reflecting inadequate antenatal care access.

What is the link between STIs and HIV?

STIs substantially increase the risk of HIV acquisition and transmission. Ulcerative STIs (herpes, syphilis, chancroid) disrupt mucosal barriers, providing HIV a portal of entry. Inflammatory STIs (gonorrhoea, chlamydia) increase HIV viral shedding in genital secretions, enhancing transmission from HIV-positive people. Conversely, HIV infection increases susceptibility to STIs and worsens their clinical course. Integrating STI and HIV services is both clinically rational and cost-effective.

What vaccines prevent STIs?

Three vaccines prevent STI-related infections: HPV vaccine (Gardasil 9, Cervarix) — prevents infection with the HPV strains responsible for cervical, oropharyngeal and other cancers, and genital warts; hepatitis B vaccine — prevents HBV infection; and JYNNEOS vaccine (Imvanex/Jynneos) — protects against mpox, which can be transmitted sexually, particularly in men who have sex with men. A gonorrhoea vaccine is in clinical development. No vaccines yet exist for chlamydia, herpes, syphilis or trichomoniasis.

What is HPV and how does it cause cancer?

Human papillomavirus (HPV) is the most common STI globally — approximately 300 million women are infected. Over 100 HPV types exist; "high-risk" types (HPV-16, HPV-18) integrate their DNA into host cell chromosomes and interfere with tumour suppressor genes, driving malignant transformation. High-risk HPV causes virtually all (>99%) cervical cancers, and a large proportion of oropharyngeal, vulvar, penile and anal cancers. The HPV vaccine prevents infection with the most oncogenic types and — if given before sexual debut — is ~90% protective against cervical cancer.

How does STI stigma affect health outcomes?

Stigma surrounding STIs prevents people from seeking testing, disclosing to partners and accessing treatment. Fear of judgment, moral labelling and discrimination leads to delayed diagnosis — allowing infections to progress (chlamydia causing PID, syphilis progressing to tertiary stages) and to spread. Stigma also affects healthcare providers, who may provide suboptimal or judgmental care. Non-judgmental, confidential STI services — including self-testing options, online results and anonymous notification systems — reduce stigma barriers.

What is the impact of STIs in pregnancy?

STIs in pregnancy cause devastating consequences: congenital syphilis (stillbirth, neonatal death, severe disability); neonatal herpes (from HSV-2 during delivery — high mortality and neurological morbidity); neonatal HIV if untreated; neonatal gonococcal and chlamydial ophthalmia (eye infection causing blindness); and HPV (vertical transmission can cause recurrent respiratory papillomatosis in infants). Antenatal STI testing and treatment is one of the highest-value maternal and neonatal health interventions.

What are the most common STIs in the European region?

In the WHO European region (including Georgia), chlamydia is consistently the most reported bacterial STI — with highest rates in young adults aged 15-25. Gonorrhoea rates have been rising across much of Europe. Syphilis has re-emerged, particularly among men who have sex with men in Western Europe. Eastern Europe (including Georgia) faces particular challenges with HIV, HCV and syphilis linked to injecting drug use. ECDC publishes annual STI surveillance reports for the EU/EEA.

What is trichomoniasis?

Trichomoniasis — caused by the protozoan parasite Trichomonas vaginalis — is the most common non-viral STI globally, with approximately 156 million new cases per year. It most commonly causes vaginal discharge and discomfort in women; most men are asymptomatic. It increases HIV acquisition risk by approximately 2-fold. Easily treated with a single dose of metronidazole or tinidazole. Diagnosis requires microscopy or NAAT; self-clearance is rare, so treatment of sexual partners is essential.

How does GMJ News cover sexually transmitted infections?

GMJ News covers WHO STI global progress reports, drug-resistant gonorrhoea alerts, HPV vaccination coverage, congenital syphilis elimination progress and the HIV-STI nexus. Georgia's STI epidemiology — including concentrated HIV and syphilis among key populations — is directly relevant to PHIG's public health mandate and the Georgian Medical Journal. All STI coverage applies standard evidence requirements and refers to WHO treatment guidelines.

Home › Topics › Sexually Transmitted Infections

Sexually Transmitted Infections

GMJ News knowledge hub · last reviewed September 2026 · Georgian Medical Journal

Summary Statistics Glossary GMJ news FAQ Documents Organizations Research

Every day, more than 1 million curable sexually transmitted infections are acquired worldwide — over 370 million new cases a year of chlamydia, gonorrhoea, syphilis and trichomoniasis — most of them asymptomatic and therefore silently transmitted (WHO). The danger is rising on two fronts: congenital syphilis is resurging, causing hundreds of thousands of adverse birth outcomes annually despite costing under a dollar to prevent with maternal screening, and antimicrobial-resistant gonorrhoea threatens to become untreatable. Meanwhile HPV vaccination — which prevents close to 90% of cervical precancers when given early — anchors the WHO cervical cancer elimination strategy. Evidence-based prevention, testing and treatment coverage is the storyline GMJ News follows.

Primary sources: WHO fact sheet — Sexually transmitted infections (STIs) · WHO health topic — STIs

Key messages

Massive and growing burden

There are approximately 374 million new curable STI infections per year (chlamydia, gonorrhoea, syphilis and trichomoniasis) — equivalent to more than 1 million new infections every day (WHO 2023).

Four are curable, four are not

Four STIs are fully curable with current antibiotics: chlamydia, gonorrhoea, syphilis and trichomoniasis. Four others are viral, incurable but manageable: HIV, herpes (HSV), HPV and hepatitis B — all addressable through prevention, vaccination or treatment.

STIs in pregnancy cause devastating harm

Untreated syphilis in pregnancy causes over 300,000 congenital syphilis cases per year — a major driver of stillbirth, neonatal death and severe disability. Despite a safe, cheap antibiotic (benzathine penicillin), congenital syphilis elimination is severely off-track globally.

Drug-resistant gonorrhoea

Gonorrhoea is developing resistance to all available antibiotic classes. The WHO "super-gonorrhoea" alert highlights that some strains are now resistant to ceftriaxone — the last recommended single-agent treatment — creating a near-untreatable STI threat.

Vaccines prevent some STIs

The HPV vaccine prevents HPV infections causing cervical, oropharyngeal and other cancers. The hepatitis B vaccine prevents HBV. JYNNEOS mpox vaccine protects against mpox which can be sexually transmitted. A gonorrhoea vaccine is in development.

Stigma is a major barrier

STI-related stigma prevents people from seeking testing, disclosure to partners and treatment. Addressing stigma through confidential, non-judgmental services and public health communication is a critical component of STI control.

Key statistics

374M

new curable STI infections/year

WHO 2023

1M+

new STI infections/day

WHO 2023

300K+

congenital syphilis cases/year

WHO

~500M

with genital HSV-2 infection

WHO 2023

~300M

women with HPV infection

WHO/IARC

XDR

gonorrhoea strains now near-untreatable in some countries

WHO

Estimated new curable STI cases per year globally (millions) — WHO 2020 estimates

Source: WHO Global progress report on HIV, viral hepatitis and sexually transmitted infections 2021.

Glossary of key terms

Sexually transmitted infection (STI)
WHOAn infection transmitted primarily through sexual contact — including vaginal, anal and oral sex. STIs can also be transmitted through blood (HIV, HBV, HCV), from mother to child (syphilis, HIV, HBV, HSV) and through skin-to-skin contact (HPV, HSV).

Chlamydia trachomatis
WHO/CDCThe most common bacterial STI globally — approximately 129 million new cases per year. Usually asymptomatic, particularly in women, leading to delayed diagnosis. Untreated, it causes pelvic inflammatory disease, infertility and ectopic pregnancy. Easily treated with azithromycin or doxycycline.

Gonorrhoea
WHO/CDCCaused by Neisseria gonorrhoeae — approximately 82 million new cases/year. Can infect the urethra, cervix, rectum, throat and eyes. Develops resistance rapidly to all antibiotic classes; extensively drug-resistant strains (near-untreatable) now documented globally. Treated with ceftriaxone as last-line.

Congenital syphilis
WHOTransmission of Treponema pallidum from an infected mother to her fetus during pregnancy or childbirth, causing stillbirth, neonatal death, and severe disability (bone deformity, blindness, deafness, neurological damage). Preventable with antenatal syphilis testing and benzathine penicillin treatment.

HPV (human papillomavirus)
WHO/IARCThe most common STI globally — approximately 300 million women infected. High-risk strains (HPV-16, HPV-18) cause cervical cancer and other anogenital and oropharyngeal cancers. Low-risk strains cause genital warts. Prevented by the HPV vaccine (Gardasil 9, Cervarix).

PrEP
WHO/CDCPre-exposure prophylaxis for HIV — HIV-negative people taking antiretroviral medicines to prevent HIV infection. Daily oral PrEP is >99% effective when taken as directed. Long-acting injectable lenacapavir (twice-yearly) demonstrated 99.9% efficacy in 2024 trials. Also relevant for STI prevention contexts.