Page 32 - Medical Parasitology_ A Textbook ( PDFDrive )

24 4 Intestinal and Genital Flagellates

virus (HIV). Babies may acquire infection during birth from infected mothers. Fomites
such as towels have been implicated in transmission.

Pathogenesis and Clinical Features

Trichomonas vaginalis infects the vagina and secretes cysteine, proteases, lactic
acid and acetic acid, which disrupt the glycogen levels and lower the pH of the vagi-
nal fluid. Trophozoite does not invade the vaginal mucosa. The infection can range
from mild irritation to severe inflammation. Infection is often asymptomatic, par-
ticularly in males, although some may develop urethritis, epididymitis and prostati-
tis. In females, it may produce severe itching in the genital area with foul smelling
yellowish green frothy discharge, dysuria, burning sensation with urination and dys-
pareunia. Cervical erosion is common. The incubation period is 4 days to 4 weeks.

Diagnosis

1. Microscopic examination
Vaginal or urethral discharge is examined microscopically in saline wet
mount preparation for the characteristic jerky and twitching motility of the
trophozoite. In males, trophozoites may be found in urine or prostatic secre-
tions. Fixed smears can be stained with acridine orange, Papanicolaou or
Giemsa stains. Direct fluorescent antibody (DFA) is another method of parasite
detection.
2. Culture
Culture of clinical specimens in Johnson’s and Trussel’s medium is recom-
mended when direct microscopy is negative.
3. Molecular diagnosis
PCR on clinical specimens.

Treatment

Treatment of both sexual partners is recommended. Metronidazole is the drug of
choice (250 mg 3 times daily for 10 days). In pregnancy, metronidazole is safe to be
given in second and third trimesters.

Prevention and Control

1. Treatment of sexual partner
2. Patients should be advised to abstain from sexual intercourse until they and their
partners have completed treatment and follow-up