Trichomoniasis is a common and curable sexually transmitted infection (STI) caused by the single-celled parasite, Trichomonas vaginalis. It is the most prevalent non-viral STI globally, infecting the urogenital tract. While the parasite can persist without treatment, a straightforward pharmacological approach offers a complete cure. Understanding the infection’s presentation, diagnosis, and treatment is the path to eliminating the parasite and preventing its spread.
Identifying the Signs of Infection
Many individuals infected with T. vaginalis experience no symptoms at all, which contributes significantly to transmission. Approximately 70% of infected people are asymptomatic carriers. When symptoms do appear, they typically manifest within five to twenty-eight days of exposure, though this timeline can vary.
Symptoms in women often involve a change in vaginal discharge, which may become thin, frothy, or yellow-green. This discharge is frequently accompanied by a strong, unpleasant, or “fishy” odor. Women may also experience burning, itching, soreness, or redness in the genital area, along with discomfort during urination or sexual intercourse.
The presentation in men is often more subtle, with most remaining asymptomatic. If symptoms occur, they usually involve mild irritation or itching inside the penis. Men may also notice a clear or pus-like discharge from the urethra or experience a burning sensation after urinating or ejaculating.
The Diagnostic Process
Confirming a T. vaginalis infection requires specific laboratory testing. The traditional method, wet-mount microscopy, involves examining a sample of vaginal or urethral fluid under a microscope to look for motile parasites. While results are immediate, sensitivity is low, often missing 20% to 60% of true infections because the organism must be alive and moving for detection.
The preferred diagnostic approach is the Nucleic Acid Amplification Test (NAAT) due to its superior accuracy. NAATs detect the parasite’s genetic material (DNA or RNA) and have a sensitivity rate approaching 100%. They are reliable for both symptomatic and asymptomatic patients, utilizing various sample types, including swabs or urine.
Rapid antigen tests are also available, offering quick results in a point-of-care setting. These tests are generally more sensitive than wet-mount microscopy but less sensitive than NAATs, performing best when the patient is symptomatic. A positive test provides the confirmation needed to start the curative treatment protocol.
Medication and Cure Protocols
The infection is cured using specific oral antimicrobial medications called nitroimidazoles. The two most common drugs are Metronidazole and Tinidazole, which eliminate the T. vaginalis parasite. Cure rates are high, ranging from 86% to 100% when the medication is taken correctly.
Treatment protocols vary based on the patient’s sex and medication. For many women, the recommended regimen is 500 mg of Metronidazole taken orally twice a day for seven days. This multi-dose approach reduces the chance of treatment failure compared to a single dose. Men are typically treated effectively with a single, high oral dose of 2 grams of Metronidazole.
Tinidazole is often used as an alternative, especially if a patient has Metronidazole resistance or intolerance. Tinidazole is generally given as a single 2-gram oral dose for both men and women. This single-dose regimen can be beneficial when patient adherence to a seven-day course is a concern.
A strict instruction accompanying treatment is the avoidance of alcohol. Combining these drugs with alcohol can trigger a severe disulfiram-like reaction, causing symptoms such as nausea, vomiting, flushing, and a rapid heart rate. Patients taking Metronidazole must abstain from alcohol for at least 72 hours after the last dose, while those on Tinidazole must avoid it for 24 hours.
Preventing Transmission and Recurrence
To ensure a complete cure and prevent spread, several steps must be followed after diagnosis. The most important measure is the simultaneous treatment of all recent sexual partners. Failure to treat a partner risks immediate reinfection.
Patients and their partners should abstain from all sexual activity until they have both completed their medication and all symptoms have fully resolved. For those receiving a single high dose, this abstinence period is typically about seven days. This allows the medication time to clear the infection completely.
Due to the high rate of reinfection, which can be as high as 20% within a few months, re-testing is strongly recommended for women. Healthcare providers recommend a retest, often called a “Test of Cure,” approximately three months after the initial treatment is completed. This follow-up testing ensures the parasite has been fully eradicated.