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Emergency and Acute Medicine – Trichomonas
Trichomonas infection is a common sexually transmitted disease caused by the protozoan Trichomonas vaginalis. It primarily affects the urogenital tract and is associated with a high prevalence of coexisting sexually transmitted infections. It can lead to important complications, including premature rupture of membranes, preterm labor, and low-birth-weight infants in pregnancy, and it may facilitate transmission of HIV. The infection is widespread, with millions of cases annually, and many individuals remain asymptomatic.
Transmission occurs through sexual contact, and the organism is a flagellated protozoan that commonly resides in the urethra, bladder, and Skene glands. The incubation period ranges from 4 to 28 days. Despite its prevalence, a significant proportion of infected individuals—particularly men—remain asymptomatic, contributing to ongoing transmission.
In females, the infection often presents as vaginitis. Symptoms may include vaginal discharge, although this is present in fewer than one-third of patients. When present, the discharge is classically described as frothy and yellow-green or gray-white, often accompanied by vulvar itching, irritation, and malodor. Dysuria, urinary urgency, and dyspareunia may also occur. On examination, findings may include diffuse cervical erythema or the characteristic “strawberry cervix” caused by punctate hemorrhages, though this is relatively uncommon. Abdominal pain is not typical.
In males, infection is frequently asymptomatic or self-limited. When symptoms occur, they usually manifest as nongonococcal urethritis, with mild dysuria, urinary urgency, and scant urethral discharge. Complications can include prostatitis, epididymitis, and, rarely, reversible infertility. Male-to-male transmission is uncommon.
Diagnosis is often clinical but can be supported by laboratory testing. In females, a saline wet mount examination of vaginal or cervical secretions may reveal motile, pear-shaped, flagellated organisms, though sensitivity is only about 60–70% and requires immediate evaluation. Elevated vaginal pH (>4.5) is common but nonspecific. Culture remains highly sensitive (around 95%) and is useful when suspicion is high but microscopy is negative. PCR testing is highly accurate but not always widely available. In males, wet mount is less sensitive, and culture or PCR is more reliable.
The differential diagnosis includes urinary tract infection, gonorrhea, chlamydia, bacterial vaginosis, candidal vaginitis, and nonspecific vaginitis, as symptoms often overlap.
Treatment is straightforward and highly effective. First-line therapy is oral metronidazole 2 g as a single dose, achieving cure rates of 90–95%, or tinidazole 2 g as a single dose. A 7-day course of metronidazole may be used in certain cases, such as urethritis or in HIV-positive patients where single-dose therapy may be less effective. Topical metronidazole gel is not recommended due to lower efficacy.
All sexual partners must be treated simultaneously to prevent reinfection, and patients should abstain from sexual activity until both partners are asymptomatic and treatment is completed. Patients should also avoid alcohol during and for at least 24 hours after metronidazole due to the risk of a disulfiram-like reaction. Condom use should be encouraged to reduce transmission risk.
Most patients can be safely discharged after treatment. Follow-up is generally not required unless symptoms persist or recur.
Important clinical considerations include recognizing that standard treatments for nongonococcal urethritis, such as azithromycin or doxycycline, do not treat Trichomonas vaginalis. Persistent vaginitis or urethritis despite standard therapy should raise suspicion for trichomoniasis.
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