Understanding the Impacts of Sexually Transmitted Infections

January 18, 2023 - Sexually transmitted infections (STIs) — sometimes referred to as sexually transmitted diseases or STDs — are viral, bacterial, or parasitic infections that spread through sexual contact. The National Institute of Allergy and Infectious Diseases (NIAID), a subset of the NIH, identifies STIs as a global health priority. Learning about and advancing prevention and treatment methods for these diseases is critical, as they can cause pelvic inflammatory disease, infertility, cervical cancer, congenital abnormalities, ectopic pregnancies, and even death.

The NIAID’s main goals regarding STIs are to develop effective prevention and treatment methods and advance existing practices. According to the organization, “to develop these strategies, basic research is necessary toward understanding the structure, function, growth, pathogenesis, and evolution of STD bacterial, viral, parasitic, protozoan, and fungal agents. Another important aspect of basic research is to examine the impact of STDs in various populations.”

In addition to the primary goals of STI research listed by the NIAID, other studies may consider improving the genomic sequencing of STIs. In turn, genomic sequencing may help investigators develop vaccines or research.

One of the many goals of STI research is prevention, referred to as the cornerstone of public health by the NIG. Prevention mechanisms vary depending on the disease and its availability. The NIH lists multiple tools for STI prevention, including vaccines, topical microbicides, and behavioral changing. Minimizing the long-term effects of the disease may include improving existing prevention tools or educating the public on the available tools.

General STI Information

Roughly one million STIs are contracted each day across the world. The WHO estimates that more than 274 million new STI infections with chlamydia, gonorrhea, syphilis, and trichomoniasis occurred in 2019. As mentioned, there are multiple classes of STIs: bacterial, parasitic, and viral. Gonorrhea, syphilis, shigella, and chlamydia are bacterial STIs; trichomoniasis and giardia are parasitic STIs; and HPV, herpes, and HIV are viral STIs. Other viral STIs include hepatitis A, B, and C.

The WHO notes that eight pathogens cause the eight most common STIs, half curable and the other half incurable. The currently curable STIs are syphilis, gonorrhea, chlamydia, and trichomoniasis, while the incurable infections are hepatitis B, herpes simplex virus (HSV), HIV, and HPV.

Transmission

Multiple types of direct contact can transmit most STIs; however, a handful can only be transmitted through sexual contact. Additionally, some STIs, like gonorrhea, chlamydia, HIV, and syphilis, can be transmitted from a mother to an infant during pregnancy or delivery.

Symptoms

The most common symptoms of STI are genital, rectal, and oral sores or bumps, painful urination, discharge from the penis, abnormal vaginal discharge or bleeding, pain with intercourse, swollen lymph nodes (commonly in the groin), abdominal pain, fever, and rashes.

The transmission of STIs between a pregnant individual and their offspring can cause stillbirth, miscarriage, premature birth, sepsis, and congenital abnormalities. Gonorrhea and chlamydia are the most likely STIs to lead to pelvic inflammatory disease and female infertility.

Risk Factors

Multiple risk factors make a patient more susceptible to acquiring an STI, including the following:

• unprotected sex
• multiple sexual partners
• history of STIs
• sexual assault
• substance use
• young age

Diagnosis

Diagnosing STIs can be another challenging or complex part of ensuring the timely and effective treatment for diseases with available therapies. According to the Mayo Clinic, it can be done through blood, urine, or other bodily fluid. Most often, tests are administered to patients already experiencing symptoms, which likely means they may have already spread the illness to partners or others.

Another effective diagnostic tool that may be better at minimizing disease spread is regular screenings. According to the Mayo Clinic, an annual HIV screen for patients 13–64, through blood or saliva tests, is recommended. Other recommended screenings include the following:

• hepatitis C screenings for individuals born between 1845 and 1965
• HIV, hepatitis B and C, chlamydia, gonorrhea, and syphilis screenings for pregnant individuals
• pap smears to test for cervical cancer in people with female reproductive organs over 21
• chlamydia and gonorrhea screenings for sexually active people under 25
• regular HIV, syphilis, chlamydia, gonorrhea, and hepatitis B screenings for men who have sex with men
• regular STI panels for people with HIV
• screening for people who have a new sexual partner

Treatment

Chlamydia, gonorrhea, syphilis, and trichomoniasis are curable — most of the time — by a round of antibiotics. One caveat is that STIs may become antibiotic resistant, rendering the condition incurable.

While not curable per se, HSV, hepatitis B, HPV, and HIV can be managed through antiviral medications. The complexities of HIV antiretroviral treatment can make the disease particularly difficult to manage; however, early treatment can prevent the progression to AIDS and death.

Chlamydia

According to StatPearls, chlamydia symptoms in individuals assigned female at birth may include vaginal discharge and bleeding, pelvic pain, dysuria, abdominal pain, nausea, vomiting, and fatigue. Upon physical examination, providers may also notice an inflamed or sensitive cervix, tender adnexal regions, and an upper right quadrant tenderness secondary to perihepatitis. For these patients, chlamydia can be confirmed through a vaginal swab, urine sample, or self-endocervical swab.

In those with male reproductive organs, the most common symptoms are dysuria, testicular pain, inflammation in the rectum or prostate, and urethral discharge. In males, chlamydia is typically diagnosed with a urine or urethral sample.

Those diagnosed with chlamydia are usually given 100 mg of doxycycline twice daily for seven days. Other options include 1 mg of azithromycin, 500 mg of levofloxacin, or 500 mg of amoxicillin once a day for seven days.

According to Queensland Health, untreated chlamydia will often result in pelvic inflammatory disease in patients with female reproductive organs. This condition can cause scarring in the fallopian tubes, resulting in fertility issues. Additionally, pregnant people with chlamydia can cause lung and eye infections in their babies. Chlamydia may also infect the urethra and cause sore, swollen testicles.

A recent study in the Expert Review of Vaccines analyzed and reviewed chlamydia vaccine progression, noting that progress has been made as the first phase I trials are up and running.

HSV

Symptoms of HSV, also known as herpes, are typically the same for all genders, with the most common symptoms including painful vesicular lesions, dysuria, fever, itching, headache, and rash. A clinical examination, genital ulceration sample, or viral culture can diagnose this STI. Common treatments for this disease include acyclovir, famciclovir, or valacyclovir.

According to the NIH, “scientists have identified certain genes and enzymes (proteins) that the virus needs to survive. They are hopeful that drugs aimed at disrupting these viral targets might lead to the design of more effective treatments.” Other research is looking to understand viral biology better to target treatments better.

Gonorrhea

Gonorrhea — often diagnosed by vulvovaginal or endocervical swabs and urine or urethral samples — is associated with symptoms such as dysuria, lower pelvic pain, vaginal bleeding, and cervical inflammation in those with female reproductive organs. Males may have dysuria, testicular pain, sore throats, and more. The typical treatment for gonorrhea consists of one intramuscular injection of 500 mg of ceftriaxone, an antibiotic treatment.

HIV

HIV symptoms are rather complex as they can vary based on the disease progression. Symptoms include fatigue, fever, chills, diarrhea, muscle pain, swollen lymph nodes, sore throat, and headaches. Providers test for HIV by using a blood or saliva sample; these are for preliminary antibody testing. Follow-up testing may include PCR or immunoassays. While HIV cannot be cured, multiple antiretroviral treatment regimens can manage symptoms and prevent disease progression.

The NIH is currently researching vaccines and treatments for HIV. Most recently, the FDA approved lenacapavir, a new antiretroviral medication for HIV patients struggling to find a current antiretroviral therapy. Additionally, research on HIV vaccines is ongoing, with recent clinical trials considering an mRNA vaccine as a potential solution. Gene therapy has also been considered as a treatment for HIV.

HPV

HPV, sometimes called genital warts, presents as venereal or anogenital warts and ulcerative lesions. HPV is often diagnosed based on a physical examination and the clinical presentation of lesions; however, a biopsy may also be done for atypical lesions. HPV cannot be cured; however, genital warts can be treated with topical therapies such as imiquimod, podofilox, and podophyllin.

Some strains of HPV are linked to cervical, anal, mouth, and throat cancer; however, HPV vaccination can help prevent infection and the resulting cancer risks.

Syphilis

Syphilis, diagnosed through serological testing, can also present as lesions or ulcers at the site of inoculation. Additional symptoms may include cutaneous lesions, maculopapular rash, stroke-like symptoms, and cranial nerve deficits, depending on the stage of disease progression. Early syphilis can be eliminated with an intramuscular injection of benzathine penicillin.

The NIH notes that one of the main priorities in syphilis research is developing diagnostic tests that are non-serological. For example, researchers are looking at saliva or urine testing as an alternative. These tests will expand diagnostic and screening tools for all patient populations, including babies who may have contracted the illness from their mothers.

Ongoing studies also look at developing single-dose oral antibiotics to effectively treat the condition, vaccines to minimize disease spread, and genomic research to understand this bacterial infection better.

Trichomoniasis

For many, trichomoniasis is asymptomatic; however, in people with female reproductive organs, trichomoniasis often causes discharge with an unpleasant odor, pruritus, dyspareunia, vaginal spotting, and vaginal irritation. Males may experience testicular pain, rectal pain, or dysuria. This condition is confirmed through the vagina or endocervical swabs, urinalysis, or urethral samples. The most common treatment for trichomoniasis is a single dose of 2 g of metronidazole for men or 500 mg of metronidazole twice daily for seven days for women.

Hepatitis B

In 2019 alone, hepatitis B, another common type of STI, contributed to 820,000 global deaths. Additionally, this disease is linked to liver issues such as cirrhosis and hepatocellular carcinoma. According to the CDC, hepatitis B symptoms may include fatigue, appetite changes, abdominal pain, nausea, jaundice, cirrhosis, and liver cancer. Diagnosing hepatitis requires serological testing. A recent article in Nature revealed that hepatitis B research has focused on nucleoside-analogue therapies and silencing cccDNA (covalently closed circular DNA) activity.

The WHO currently has its Global Health Sector Strategy on HIV, Hepatitis, and Sexually Transmitted Infections for 2022–2030 in action. And this strategy hopes to develop STI prevention, testing, and treatment standards; strengthen disease surveillance; combat the economic burden of STIs; and advance research on STIs. Beyond the efforts of the WHO, individual countries, healthcare organizations, and providers are encouraged to implement STI education and screenings, widen access to treatment and prevention tools, and research new and innovative therapies.