Trichomoniasis

Trichomoniasis (often referred to as "trich") is an infectious disease caused by the parasite Trichomonas vaginalis. It is a common sexually transmitted infection (STI) that can affect both men and women but is more frequently diagnosed in women.

Signs and Symptoms

Approximately 70% of individuals infected with Trichomonas vaginalis are asymptomatic. When symptoms do occur, they typically manifest within 5 to 28 days after exposure. Common symptoms include itching in the genital area, a thin, bad-smelling vaginal discharge, burning during urination, and pain during sexual intercourse. In rare cases, lower abdominal pain may also be present.

Trichomoniasis can increase the risk of acquiring HIV/AIDS and can cause complications during pregnancy, including preterm delivery and low birth weight. In men, the infection can lead to asymptomatic urethritis and prostatitis, potentially causing chronic inflammation and increasing the risk of prostate cancer.

Causes

Trichomonas vaginalis is transmitted through sexual contact, including vaginal, oral, and anal sex, as well as genital touching. The human genital tract is the sole reservoir for this protozoan parasite. The parasite exerts mechanical stress on host cells, leading to cell death and subsequent ingestion of cell fragments by the parasite.

Diagnosis

There are three primary methods for diagnosing trichomoniasis:

1. Saline Microscopy: This common method involves examining a vaginal, endocervical, or penile swab specimen under a microscope. A positive result is indicated by the presence of trichomonads. While inexpensive, this method has a low sensitivity (60-70%), which can result in false negatives due to inadequate samples.
2. Culture: Historically considered the "gold standard," Trichomonas vaginalis culture tests are relatively inexpensive but still have a sensitivity of 70-89%.
3. Nucleic Acid Amplification Tests (NAATs): These tests are highly sensitive (80-90%) and more costly than microscopy and culture. They are effective in detecting the parasite's DNA.

Prevention

Preventing trichomoniasis involves several strategies:

• Abstaining from sexual activity
• Using condoms consistently
• Avoiding douching
• Testing for STIs before engaging in sexual activity with a new partner

Despite the effectiveness of these measures, there are no routine, standard screening protocols for the general population. The Centres for Disease Control and Prevention (CDC) recommends testing for females with vaginal discharge and considers testing for those at higher risk or with HIV.

Treatment

The primary treatment for trichomoniasis is a single oral dose of metronidazole or tinidazole. This treatment is effective in 95-97% of cases, with a few cases showing resistance to metronidazole. Sexual partners should also be treated to prevent reinfection. For pregnant women, caution is advised, especially in the first trimester.

Studies indicate that women with HIV have better cure rates with a seven-day treatment regimen compared to a single dose. Topical treatments are generally less effective than oral antibiotics due to the genitourinary structures acting as reservoirs for the parasite.

Epidemiology

In 2015, there were approximately 122 million new cases of trichomoniasis globally. It is more prevalent in women than men and is the most common non-viral STI in the United States, with an estimated 3.7 million prevalent cases and 1.1 million new cases annually. The infection rate in the general U.S. population is about 3%, with higher rates (7.5-32%) in moderate-to-high-risk populations.

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Self-assessment MCQs (single best answer)

What is the causative agent of trichomoniasis?

What percentage of individuals infected with _Trichomonas vaginalis_ are asymptomatic?

Which diagnostic method for trichomoniasis is considered highly sensitive but more costly?

What is the primary treatment for trichomoniasis?

Which of the following is NOT a common symptom of trichomoniasis?

Trichomoniasis can increase the risk of which serious condition?

Which population group has the highest prevalence of trichomoniasis in the United States?

What is the infection rate of trichomoniasis in the general U.S. population?

Which of the following is NOT a recommended prevention strategy for trichomoniasis?

In men, trichomoniasis can lead to which condition, potentially causing chronic inflammation?