STIs and HIV/AIDS: Basic Information, History, and Global Prevalence

Every single day, more than 1 million people acquire a sexually transmitted infection worldwide. These infections affect individuals across all demographics, yet many remain unaware they are infected. Understanding STIs-what they are, how they spread, and how to prevent them-is crucial for public health, especially given their far-reaching consequences on reproductive health, pregnancy outcomes, and their connection to HIV transmission.

What are sexually transmitted infections? 🔗

A sexually transmitted infection is an infection caused by bacteria, viruses, fungi, or parasites that spreads through sexual contact. These infections primarily transmit through vaginal, anal, or oral sex, though some can also spread through skin-to-skin contact in the genital area. More than 30 different pathogens are known to transmit sexually, ranging from bacterial infections like gonorrhea to viral infections like herpes.

What makes STIs particularly concerning is that many infected individuals show no symptoms initially. This asymptomatic nature means people can unknowingly transmit infections to others while remaining unaware of their own infection status. Some STIs can also pass from mother to child during pregnancy, childbirth, or breastfeeding, creating additional transmission pathways beyond sexual contact.

From venereal diseases to sexually transmitted infections 🔗

The language we use to describe these conditions has evolved significantly. Until the 1990s, these infections were commonly called venereal diseases-a term derived from Venus, the Roman goddess of love. However, this terminology carried negative connotations and stigma that hindered public health efforts.

In 1999, the World Health Organization recommended adopting the more inclusive term “sexually transmitted infection” instead of “sexually transmitted disease.” This shift in language was deliberate and meaningful. The term STI acknowledges that many people carry these infections without developing obvious disease symptoms, yet they still require treatment and can transmit the infection to others. This change aimed to reduce stigma, improve healthcare-seeking behavior, and recognize the full spectrum of infection states.

A historical perspective on STIs and breakthrough treatments 🔗

Sexually transmitted infections have plagued humanity for centuries. Historical documents from ancient Egypt, Greece, and Rome describe symptoms similar to gonorrhea and syphilis, though people at the time attributed these ailments to divine punishment or moral failings rather than infectious agents.

Syphilis, in particular, caused devastating outbreaks throughout history. For centuries, treatment options were limited, dangerous, and often ineffective. Mercury compounds were widely used despite causing severe poisoning, leading to the grim saying about having “a night with Venus, a lifetime with Mercury.” In 1910, Paul Ehrlich and Sahachiro Hata discovered Salvarsan, an arsenic-based compound that became the first effective treatment for syphilis, though it too had significant toxic side effects.

The true breakthrough came with Alexander Fleming’s discovery of penicillin in 1928. By 1943, penicillin was being used to treat syphilis patients, and by 1947 it had become the standard treatment, reducing UK syphilis cases by 90% within a decade. This antibiotic revolutionized STI treatment and saved countless lives, transforming what was once a devastating and often fatal disease into a curable condition.

The alarming global and Indian scenario 🔗

Despite medical advances, STIs remain a massive global health burden. According to WHO, in 2020 there were an estimated 374 million new infections with four curable STIs: chlamydia (129 million), gonorrhea (82 million), syphilis (7.1 million), and trichomoniasis (156 million). Additionally, an estimated 520 million people live with genital herpes, and 300 million women have HPV infection, which causes cervical cancer.

India faces particular challenges with STI prevalence. In 2021, India recorded over 94 million STI cases, the second-highest number globally after China. Approximately 6% of India’s adult population acquires an STI or reproductive tract infection annually. Between 2007 and 2017, over 34 million episodes of these infections were treated in India, reflecting the enormous scale of the problem.

The prevalence varies significantly across different population groups in India, with rates being much higher among key populations practicing high-risk behaviors compared to the general population where prevalence ranges from 0 to 3.9 percent.

Common sexually transmitted infections and their symptoms 🔗

Syphilis 🔗

Caused by the bacterium Treponema pallidum, syphilis progresses through distinct stages. The primary stage features painless sores called chancres at the infection site. If untreated, it advances to secondary syphilis with skin rashes and mucous membrane lesions. Without treatment, it can progress to late-stage syphilis affecting the heart, brain, and other organs.

Gonorrhea 🔗

This bacterial infection commonly causes urethral discharge and burning during urination in men, while women may experience vaginal discharge and pelvic pain. However, many infections are asymptomatic, particularly in women. Untreated gonorrhea can lead to pelvic inflammatory disease and infertility.

Genital herpes 🔗

Caused by herpes simplex virus, this infection produces painful blisters or sores in the genital area. While the virus remains in the body permanently, antiviral medications can manage outbreaks and reduce transmission risk.

Chlamydia 🔗

Often called a “silent” infection because most people show no symptoms, chlamydia can cause serious reproductive complications if untreated, including infertility in both men and women.

Chancroid 🔗

This bacterial infection causes painful genital ulcers and swollen lymph nodes in the groin area. While less common than other STIs, it significantly increases HIV transmission risk.

Identifying people at highest risk 🔗

While anyone sexually active can acquire an STI, certain populations face heightened vulnerability. These include commercial sex workers and their clients, men who have sex with men, transgender individuals, injecting drug users, and their partners. Adolescents and young adults face particular risk due to biological factors, lack of information, and limited healthcare access.

Other at-risk groups include migrant workers, truck drivers, street children, and prison inmates-populations that often face barriers to healthcare and prevention services. Understanding these risk factors helps target prevention and treatment efforts where they’re most needed.

The critical connection between STIs and HIV/AIDS 🔗

The relationship between STIs and HIV transmission represents one of the most important aspects of sexual health. This connection operates through four key mechanisms:

Increased biological susceptibility: STIs that cause ulcers or sores create breaks in the skin that make it easier for HIV to enter the body during sexual contact. Even non-ulcerative STIs increase susceptibility by causing inflammation and recruiting immune cells to the genital area.

Enhanced HIV transmission: People infected with both HIV and another STI have more HIV in their genital fluids, making them more likely to transmit the virus to sexual partners.

Increased viral shedding: Research shows that STIs increase the amount of HIV shed in genital secretions, with conditions causing inflammation showing the strongest associations with increased viral presence.

Facilitated transmission pathways: STIs can create an environment that allows less-fit HIV variants to establish infection, essentially creating conditions that favor HIV transmission when it might not otherwise occur.

Studies have demonstrated that individuals infected with STIs are two to five times more likely to acquire HIV if exposed through sexual contact, highlighting the critical importance of integrated STI and HIV prevention efforts.

National strategies for STI control in India 🔗

The National AIDS Control Organization has developed a comprehensive four-pronged strategy for managing and controlling STIs across India:

First, provision of standardized STI management to the general population through integration with reproductive and child health services. This includes establishing designated clinics at district and sub-district levels using syndromic case management approaches that allow treatment without expensive laboratory tests.

Second, targeted STI services for high-risk populations through specialized interventions. These programs, delivered through NGO partnerships, provide comprehensive packages including behavior change communication, condom distribution, counseling, HIV testing, and STI treatment specifically designed for sex workers, men who have sex with men, transgender individuals, and injecting drug users.

Third, laboratory support and surveillance systems to monitor STI trends, track antimicrobial resistance patterns, and ensure quality diagnostic services where available.

Fourth, integration and convergence with other health programs, particularly reproductive, maternal, and child health services, ensuring that STI prevention and management reaches women during antenatal care and addresses vertical transmission to infants.

What do you think? Given the silent nature of many STIs and their serious health consequences, how can we reduce stigma and encourage more people to seek regular testing? What role do you believe education systems should play in providing comprehensive sexual health information to young people before they become sexually active?

References

1. https://www.who.int/news-room/fact-sheets/detail/sexually-transmitted-infections-(stis)
2. https://www.cdc.gov/sti/about/index.html
3. https://my.clevelandclinic.org/health/diseases/9138-sexually-transmitted-diseases–infections-stds–stis
4. https://en.wikipedia.org/wiki/Sexually_transmitted_infection
5. https://applications.emro.who.int/aiecf/web79.pdf
6. https://pubmed.ncbi.nlm.nih.gov/25969906/
7. https://pmc.ncbi.nlm.nih.gov/articles/PMC3956094/
8. https://www.sciencemuseum.org.uk/objects-and-stories/history-syphilis-part-two-treatments-cures-and-legislation
9. https://link.springer.com/article/10.1186/s41182-025-00744-2
10. https://www.medindia.net/health_statistics/diseases/sexually-transmitted-diseases-india-statistics.asp
11. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0279048
12. https://www.nhp.gov.in/disease/reproductive-system/sexually-transmitted-infections-stis
13. https://www.hiv.gov/hiv-basics/staying-in-hiv-care/other-related-health-issues/sexually-transmitted-diseases
14. https://www.health.ny.gov/diseases/aids/consumers/hiv_basics/stds_hiv.htm
15. https://pmc.ncbi.nlm.nih.gov/articles/PMC2923028/
16. https://www.ncbi.nlm.nih.gov/books/NBK573161/
17. https://dhss.delaware.gov/dph/dpc/stdhiv/
18. https://naco.gov.in/sites/default/files/STI%20Operational%20Guidelines.pdf
19. https://naco.gov.in/prevention-strategies