Trichomoniasis

Trichomoniasis is one of the most common curable sexually transmitted infections (STIs), caused by infection with a protozoan parasite called Trichomonas vaginalis. Despite being easily treatable, it often goes undiagnosed because many people don't have symptoms.

Overview

Trichomoniasis, often called "trich," is a sexually transmitted infection that affects millions of people worldwide. According to the World Health Organization, it's the most common non-viral STI globally, with an estimated 156 million new cases occurring each year. In the United States alone, the CDC estimates that more than 2 million people have the infection, though only about 30% develop any symptoms.

The infection is caused by Trichomonas vaginalis, a single-celled protozoan parasite that moves using whip-like structures called flagella. This microscopic organism thrives in the warm, moist environment of the urogenital tract. In women, the infection primarily affects the lower genital tract, including the vulva, vagina, cervix, and urethra. In men, the infection most commonly affects the urethra, but can also involve the prostate and seminal vesicles.

What makes trichomoniasis particularly concerning from a public health perspective is its ability to increase the risk of acquiring or transmitting other STIs, including HIV. The inflammation caused by trichomoniasis can make it easier for HIV to enter the body and can also increase the HIV viral load in people who are already infected. Additionally, untreated trichomoniasis during pregnancy can lead to premature delivery and low birth weight babies.

Symptoms

The symptoms of trichomoniasis can vary significantly between individuals and between men and women. Importantly, about 70% of infected people do not have any signs or symptoms, which contributes to its spread as people unknowingly transmit the infection to their partners.

Symptoms in Women

  • Vaginal itching and irritation, often severe
  • Vaginal discharge that may be:
    • Frothy or foamy in appearance
    • Yellow-green or gray in color
    • Foul-smelling (often described as "fishy")
    • More profuse than normal
  • Lower abdominal pain or pelvic discomfort
  • Pain or burning during urination (dysuria)
  • Pain during sexual intercourse (dyspareunia)
  • Vaginal bleeding, particularly after intercourse
  • Swelling and redness of the vulva
  • Unpredictable menstruation or spotting between periods

Symptoms in Men

Men are more likely to be asymptomatic than women, but when symptoms occur, they may include:

  • Discharge from the penis (usually thin and white)
  • Burning sensation after urination or ejaculation
  • Itching or irritation inside the penis
  • Redness or swelling at the tip of the penis
  • Frequent urge to urinate
  • Pain during ejaculation

General Symptoms

During Pregnancy

  • Pain during pregnancy
  • Increased risk of preterm labor
  • Premature rupture of membranes
  • Low birth weight infant

Timeline of Symptoms

When symptoms do develop, they typically appear within 5 to 28 days after infection, though this can vary. Some people may develop symptoms months after infection, while others never develop symptoms at all.

Causes

Trichomoniasis is caused by the protozoan parasite Trichomonas vaginalis. Understanding how this organism spreads and survives is crucial for prevention and treatment.

The Parasite

  • Trichomonas vaginalis: A flagellated protozoan parasite
    • Single-celled organism
    • Pear-shaped with four flagella for movement
    • Measures 10-20 micrometers in length
    • Survives only in human urogenital tract
    • Cannot survive long outside the human body

Transmission Methods

  • Sexual contact: Primary mode of transmission
    • Vaginal intercourse
    • Genital touching
    • Sharing sex toys without proper cleaning
    • Can spread from vulva to vulva contact
  • Vertical transmission: From mother to baby during childbirth (rare)
  • Non-sexual transmission: Extremely rare but possible through:
    • Damp towels or washcloths (very unlikely)
    • Toilet seats (theoretical but not proven)
    • Swimming pools or hot tubs (extremely unlikely)

Factors That Facilitate Transmission

  • The parasite's ability to adhere to epithelial cells
  • Production of enzymes that damage host cells
  • Ability to evade immune responses
  • Survival in slightly alkaline pH environments
  • Movement through mucus using flagella

Why Some People Are More Susceptible

  • Alterations in vaginal pH (normal is 3.8-4.5)
  • Changes in vaginal flora
  • Hormonal fluctuations
  • Compromised immune system
  • Presence of other STIs

Risk Factors

Several factors can increase the likelihood of contracting trichomoniasis:

  • Sexual activity factors:
    • Multiple sexual partners
    • New sexual partner
    • Unprotected sex (without condoms)
    • History of previous STIs
    • Partner with trichomoniasis or unknown STI status
  • Demographic factors:
    • Women are more frequently diagnosed than men
    • Higher rates in older women compared to younger
    • African American women have higher infection rates
    • Lower socioeconomic status
  • Behavioral factors:
    • Douching (disrupts vaginal flora)
    • Smoking
    • Drug or alcohol use affecting judgment
    • Sex work
  • Medical factors:
    • HIV infection
    • Bacterial vaginosis
    • Other vaginal infections
    • Compromised immune system
  • Environmental factors:
    • Limited access to healthcare
    • Lack of STI education
    • Incarceration

Diagnosis

Accurate diagnosis of trichomoniasis is important because symptoms can mimic other infections, and many infected individuals are asymptomatic. Several diagnostic methods are available.

Clinical Evaluation

  • Medical history including sexual history
  • Physical examination
  • Pelvic examination in women
  • Urethral examination in men
  • Assessment of symptoms and their duration

Laboratory Tests

  • Wet mount microscopy:
    • Immediate examination of vaginal fluid
    • Can see moving parasites (60-70% sensitivity)
    • Quick results (within minutes)
    • Requires fresh sample
  • Culture:
    • Gold standard for many years
    • Takes 3-7 days for results
    • More sensitive than microscopy
  • Nucleic Acid Amplification Tests (NAATs):
    • Most sensitive method (95-100%)
    • Can use urine, vaginal, or urethral samples
    • Results in 1-2 days
    • Can test for multiple STIs simultaneously
  • Rapid antigen tests:
    • Results in 10-45 minutes
    • Good sensitivity and specificity
    • Point-of-care testing available

Sample Collection

  • Women: Vaginal swab (self-collected or clinician-collected)
  • Men: Urethral swab or first-catch urine
  • Both: Urine sample for NAAT testing

When to Test

  • Presence of symptoms
  • Sexual partner diagnosed with trichomoniasis
  • Routine STI screening for at-risk individuals
  • Pregnant women with symptoms or risk factors
  • Before starting treatment for other vaginal infections
  • 3 months after treatment to check for reinfection

Treatment Options

Trichomoniasis is easily curable with appropriate antibiotic treatment. The same treatment regimen is used for both men and women, and all sexual partners must be treated simultaneously to prevent reinfection.

First-Line Treatment

  • Metronidazole:
    • Single dose: 2 grams orally in one dose
    • Alternative: 500 mg orally twice daily for 7 days
    • Cure rate: 84-98%
    • Safe in pregnancy (after first trimester)
  • Tinidazole:
    • Single dose: 2 grams orally in one dose
    • May have fewer side effects than metronidazole
    • Higher cure rate in some studies
    • More expensive than metronidazole

Treatment Considerations

  • Alcohol avoidance: No alcohol during treatment and for:
    • 24 hours after metronidazole
    • 72 hours after tinidazole
    • Can cause severe nausea and vomiting
  • Sexual abstinence: Until all partners complete treatment and symptoms resolve (usually 7 days)
  • Partner treatment: All sexual partners in past 60 days must be treated
  • Test of cure: Recommended for all women 3 months after treatment

Treatment Failure

If symptoms persist after treatment:

  • Rule out reinfection from untreated partner
  • Consider medication resistance (5% of cases)
  • Retreatment options:
    • Metronidazole 500 mg twice daily for 7 days
    • High-dose tinidazole (2 g daily for 5 days)
    • Consultation with infectious disease specialist

Treatment in Special Populations

  • Pregnancy:
    • Treatment recommended to prevent complications
    • Metronidazole 2 g single dose preferred
    • Safe after first trimester
  • Breastfeeding:
    • Metronidazole enters breast milk
    • Single dose: stop breastfeeding for 12-24 hours
    • Multiple doses: may continue breastfeeding
  • HIV-positive individuals:
    • Same treatment regimen
    • May have higher failure rates
    • More frequent follow-up recommended

Prevention

Preventing trichomoniasis involves reducing exposure risk and maintaining good sexual health practices:

Primary Prevention

  • Safer sex practices:
    • Consistent and correct condom use
    • Dental dams for oral-genital contact
    • Limiting number of sexual partners
    • Mutual monogamy with uninfected partner
  • Communication:
    • Discuss STI testing with partners
    • Know your partner's STI status
    • Honest disclosure of infections
  • Regular testing:
    • Annual screening for sexually active women
    • More frequent testing for high-risk individuals
    • Testing before new sexual relationships

Risk Reduction Strategies

  • Avoid douching (disrupts vaginal flora)
  • Limit alcohol and drug use that impairs judgment
  • Prompt treatment if diagnosed
  • Ensure partner treatment
  • Complete full course of medication
  • Abstain from sex during treatment

Education and Awareness

  • Understanding transmission methods
  • Recognizing symptoms
  • Knowing when to seek testing
  • Reducing stigma around STIs
  • Promoting open communication about sexual health

When to See a Doctor

Seek medical attention if you experience:

  • Any unusual genital discharge, odor, or irritation
  • Pain or burning during urination
  • Itching, redness, or swelling of genitals
  • Pain during sexual intercourse
  • Lower abdominal or pelvic pain
  • Unusual vaginal bleeding
  • If a sexual partner has been diagnosed with trichomoniasis or any STI

During pregnancy, seek immediate care for:

  • Any vaginal discharge changes
  • Pelvic pain or pressure
  • Signs of preterm labor
  • Fever with genital symptoms

Remember, many people with trichomoniasis have no symptoms. Regular STI screening is important if you're sexually active, especially with new or multiple partners.

Frequently Asked Questions

Can trichomoniasis go away on its own?

No, trichomoniasis will not go away without treatment. The infection can persist for months or years if left untreated and can be transmitted to partners during this time.

Can you get trichomoniasis without being sexually active?

While extremely rare, non-sexual transmission is theoretically possible through contaminated objects. However, the parasite cannot survive long outside the human body, making sexual transmission by far the most common route.

How long after treatment before I can have sex again?

You should wait at least 7 days after you and your partner(s) have completed treatment and symptoms have resolved before resuming sexual activity.

Can men carry trichomoniasis without knowing?

Yes, men are more likely than women to be asymptomatic carriers. They can unknowingly transmit the infection to their partners.

Does having trichomoniasis once make you immune?

No, you can get trichomoniasis again. There is no immunity after infection, and reinfection is common if partners are not treated simultaneously.

References

  1. Centers for Disease Control and Prevention. Sexually Transmitted Infections Treatment Guidelines, 2021 - Trichomoniasis. MMWR Recomm Rep. 2021;70(4):1-187.
  2. Kissinger P. Trichomonas vaginalis: a review of epidemiologic, clinical and treatment issues. BMC Infect Dis. 2015;15:307.
  3. Muzny CA, et al. Updates in Trichomonas Treatment including Persistent Infection and 5-Nitroimidazole Hypersensitivity. Curr Opin Infect Dis. 2020;33(1):73-77.
  4. World Health Organization. Global incidence and prevalence of selected curable sexually transmitted infections. Geneva: WHO; 2023.
  5. American College of Obstetricians and Gynecologists. Vaginitis in Nonpregnant Patients: ACOG Practice Bulletin, Number 215. Obstet Gynecol. 2020;135(1):e1-e17.

Medical Disclaimer: This information is for educational purposes only and should not replace professional medical advice. Always consult with a qualified healthcare provider for diagnosis and treatment of any medical condition.