Overview
Trichomonas vaginalis is a protozoan parasite and is one of the most common parasitic causes of sexually transmitted infections. Females are more frequently affected than males. The parasite exists in the trophozoite form, which is flagellated and actively motile. In females, trophozoites reside mainly in the vagina and urethra, while in males they are found in the seminal vesicles and prostate. The trophozoite stage is responsible for both infection and diagnosis. A significant proportion of infected individuals may remain asymptomatic, contributing to continued transmission of the disease
Symptoms
Clinical manifestations of Trichomonas vary from asymptomatic carriage to acute or chronic disease. Approximately 25 to 50 percent of infected individuals do not show symptoms but are still capable of transmitting the infection.
In acute infection, females commonly present with vulvovaginitis. This is characterized by a thin, profuse, foul-smelling, purulent vaginal discharge. In a small percentage of cases, the vaginal mucosa shows a characteristic strawberry appearance. Chronic infection is usually milder, with symptoms such as itching, pruritus, and pain during coitus.
In females, common symptoms include vaginal discharge along with itching and burning sensations. Males generally remain asymptomatic, although a few may develop urethritis or prostatitis. The difference in symptom severity between genders often leads to underdiagnosis in males and persistence of infection in the community
Causes
Trichomoniasis is caused by the protozoan parasite Trichomonas vaginalis. The trophozoite is the only form found in humans and is responsible for disease transmission. It is a flagellated organism with characteristic motility, which helps in its identification during microscopic examination.
The organism survives in the urogenital tract, where favorable conditions allow multiplication and persistence. Since there is no cyst stage, transmission requires direct transfer of trophozoites from an infected individual to a susceptible host, primarily during sexual contact
Risk Factors
The major risk factor for Trichomonas is unprotected sexual contact with an infected partner. Asymptomatic females act as an important reservoir of infection and play a significant role in disease spread. Lack of awareness, delayed diagnosis, and absence of treatment in asymptomatic cases further increase transmission risk. In pregnancy, infection is associated with adverse outcomes such as preterm birth and low birth weight. Trichomoniasis is also linked with pelvic inflammatory disease and an increased risk of HIV transmission, making it an important public health concern
Prevention
Prevention of trichomonas relies mainly on interrupting sexual transmission and early detection of infection. Safe sexual practices and identification of asymptomatic carriers are essential to reduce disease spread. Laboratory diagnosis plays a key role in prevention and control.
Direct microscopy is a simple and commonly used diagnostic method. Samples such as vaginal discharge, urethral discharge, urine sediment, and prostatic secretions are used. For accurate detection of motile trophozoites, samples should be examined as soon as possible, preferably within 10 to 20 minutes of collection.
Wet saline mount microscopy is widely used to demonstrate the characteristic jerky motility of trophozoites, with moderate sensitivity and high specificity. Permanent staining methods such as Giemsa and Papanicolaou stains are useful for demonstrating trophozoite morphology on dried smears.
Acridine orange fluorescent staining provides a rapid and more sensitive alternative to wet mount examination. Direct fluorescent antibody tests using labeled monoclonal antibodies further improve detection rates. Timely diagnosis and appropriate management help prevent complications and reduce ongoing transmission of the infection
