Trichomonas

# **Morphology, Life Cycle, Pathogenesis, and Clinical Features** ## **Introduction** *Trichomonas* is a genus of protozoan parasites that differ from other flagellates because they **exist only in the trophozoite stage**—they do not form cysts. ### **Species of *Trichomonas* in Humans** There are three species of *Trichomonas* that infect humans: - **Trichomonas vaginalis** – Causes **urogenital infections**. - **Trichomonas hominis** – A commensal in the **intestine**. - **Trichomonas tenax** – A commensal in the **oral cavity**. Among these, *T. vaginalis* is the **only pathogenic species**. --- ## **Trichomonas vaginalis** ### **History and Distribution** - *T. vaginalis* was first identified by **Donné in 1836** in **vaginal secretions**. - Trichomoniasis is a **sexually transmitted infection (STI)** with a **prevalence of 5%–75%**, depending on the population:**5% in general hospital patients**. - **75% in sex workers**. --- ## **Morphology of *T. vaginalis*** - **Shape**: Pear-shaped or ovoid. - **Size**: 10–30 µm in length and 5–10 µm in breadth. - **Flagella**:Has **four anterior flagella** for movement. - A **fifth flagellum** runs along the undulating membrane, supported by a flexible rod called the **costa**. - **Axostyle**: A **rigid, rod-like structure** running along the body and projecting **posteriorly**. - **Cytoplasm**: Contains **siderophilic granules** (most numerous alongside the axostyle and costa). - **Motility**: **Rapid, jerky, twitching movement** under a microscope. --- ## **Habitat of *T. vaginalis*** - **Females**: Found in the **vagina and cervix**, sometimes in the Bartholin’s glands, urethra, and urinary bladder. - **Males**: Found in the **anterior urethra**, prostate, and preputial sac. --- ## **Life Cycle of *T. vaginalis*** The life cycle of *T. vaginalis* occurs **entirely in a single host** (either male or female). ### **Mode of Transmission** - **Sexual transmission** is the **primary mode** of infection. - Often coexists with other **sexually transmitted infections (STIs)** such as:**Candidiasis** - **Gonorrhea** - **Syphilis** - **HIV** - **Non-sexual transmission**:Babies **can get infected** during vaginal delivery. - Contaminated **towels, toilet seats, and bath water** have been implicated in transmission, but this is rare. - **The infective form is the trophozoite** since *T. vaginalis* does not form cysts. - **Incubation period**: Approximately **10 days** (range: 4 days to 4 weeks). --- ## **Pathogenesis of Trichomoniasis** - *T. vaginalis* primarily infects **squamous epithelium** (not columnar epithelium). - Produces **cysteine proteases, adhesins, lactic acid, and acetic acid**, which:Disrupt **glycogen metabolism**. - Lower **vaginal pH**, making the environment more favorable for infection. - **Obligate parasite**: Cannot survive outside the host for long. - Causes **inflammation and tissue damage**, leading to:**Petechial hemorrhages** and **capillary dilation** (causing the "strawberry cervix" appearance). - **Metaplasia and desquamation** of the vaginal epithelium. - **Intracellular edema**, resulting in **chicken-like epithelial cells** (a hallmark of trichomoniasis). --- ## **Clinical Features of Trichomoniasis** ### **In Males** - **Usually asymptomatic**. - Some may develop:**Urethritis** (pain and burning during urination). - **Epididymitis** (inflammation of the epididymis). - **Prostatitis** (inflammation of the prostate). ### **In Females** - **Symptomatic cases present with**:**Pruritic vaginitis** (intense itching). - **Yellowish-green, frothy vaginal discharge** (with a foul smell). - **Dysuria** (painful urination). - **Dyspareunia** (pain during intercourse). - **Cervical erosion** (due to inflammation). - **Complications**:**Endometritis** and **pyosalpingitis** (rare). - **Neonatal pneumonia and conjunctivitis** (in infants born to infected mothers). - **Incubation period**: **4 days to 4 weeks**. --- Trichomoniasis, caused by *T. vaginalis*, is a **common sexually transmitted infection** that primarily affects the **urogenital tract**. While **males are often asymptomatic**, females may experience **itching, frothy vaginal discharge, and discomfort**. The parasite **does not form cysts**, meaning transmission occurs directly via **sexual contact** or, in rare cases, through contaminated fomites. The disease can be **associated with other STIs**, highlighting the importance of **early detection and treatment**. # **Laboratory Diagnosis, Treatment, and Prevention of *Trichomonas vaginalis*** ## **Laboratory Diagnosis** The diagnosis of *T. vaginalis* infection is based on **microscopic examination, culture, antigen detection, and molecular methods**. ### **1. Microscopic Examination** Microscopy is the **most commonly used** method for detecting *T. vaginalis* in clinical samples. #### **a) Wet Mount Preparation** - **Sample**: Vaginal or urethral discharge, urine, or prostatic secretions.