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Methods for Detection of Trichomonas vaginalis
a report by
Marcia M Hobbs
and Arlene C Seña
1. Associate Professor of Medicine and Microbiology and Immunology;
2. Clinical Associate Professor of Medicine, Division of Infectious Diseases, University of North Carolina at Chapel Hill
Trichomonas vaginalis is a protozoan pathogen of the human urogenital Diagnosis by wet-mount requires visualisation of viable, motile protozoa;
tract. The World Health Organization (WHO) estimates that trichomoniasis therefore, specimens must be examined immediately. The sensitivity of
accounts for more than half of all curable sexually transmitted infections wet-mount microscopy can be further reduced as a result of delays between
Although accurate surveillance data are lacking, there specimen collection and examination.
Despite its limited sensitivity,
were an estimated five million new cases of trichomoniasis each year in the wet-mount microscopy may be widely used because it is inexpensive and
US during the late 1990s, exceeding similar figures for gonorrhea and positive results can be obtained quickly, allowing patients to be treated
chlamydial infections combined.
The prevalence of T. vaginalis has been during a single clinic visit. T. vaginalis can also be visualised in fixed vaginal,
reported to be as high as 26% among female STD clinic patients and 22% cervical or urine sediment smears stained using various staining methods,
among HIV-positive women.
Recurrent infections are common in women, including Gram, Giemsa, Papanicolaou, periodic acid-Schiff, acridine
predominantly due to untreated sexual partners.
Transmitted primarily by orange, fluorescein and immunoperoxidase. Papanicolaou-stained smears
sexual intercourse, T. vaginalis causes vaginitis in women and urethritis in can be used to detect T. vaginalis in asymptomatic women during routine
men. While trichomoniasis is well recognised as an aetiological cause of examinations.
Detection using the Papanicolaou test has reported
vaginitis, the proportion of non-gonococcal urethritis in men due to sensitivity of 60% and specificity of 95–97%;
however, confirmation of
T. vaginalis has been estimated to be between 11 and 18%.
A substantial trichomonads using another method is recommended.
proportion of infections are asymptomatic, necessitating reliable testing
methods. Trichomoniasis is also implicated in various other genito-urinary Culture
syndromes, including cervicitis, epididymitis and prostatitis.
Associations Culture, using a variety of liquid and semi-solid media, remains the
between maternal trichomoniasis and premature rupture of the reference standard for diagnosis of trichomoniasis in women.
membranes and pre-term delivery have been reported,
and there is pouches containing modified Diamond’s medium are commercially
mounting evidence of an association with cervical cancer.
available and convenient (InPouch TV, Biomed Diagnostics, White City, OR).
After inoculation with a vaginal swab specimen or urine sediment, cultures
Infection with T. vaginalis can be a marker for high-risk sexual behaviour, are incubated for three to five days at 37°C in a 5% CO
and frequently occurs concomitantly with other STIs, including examined daily using microscopy for motile trichomonads. Cultures from
gonorrhea and chlamydia.
Trichomoniasis is associated with incident women with trichomoniasis are usually positive within the first three days.
herpes simplex virus (HSV)-2 infection
and with genital HSV-2 shedding In studies comparing the detection of T. vaginalis using culture and highly
in infected women.
As with other STIs, trichomoniasis in the male or sensitive nucleic acid amplification tests, sensitivity estimates for culture
female genital tract is associated with increased sexual transmission of
Co-infection with T. vaginalis and HIV may increase the
Marcia M Hobbs is an Associate Professor of Medicine and
infectiousness of both organisms.
As the prevalence of trichomoniasis Microbiology and Immunology at the University of North
is so high, a large proportion of HIV infections could be attributable to
Carolina at Chapel Hill, and Co-Director of the North
Carolina Sexually Transmitted Infections and Topical
T. vaginalis infection in populations where both infections are common.
Microbicides Co-operative Research Center. Dr Hobbs’
Diagnosis of trichomoniasis based solely on clinical signs and symptoms
research focuses on the development and implementation
of molecular diagnostic and genotyping tests for non-viral
is unreliable because the spectrum of infection is broad and other sexually
sexually transmitted pathogens. She is a laboratory
transmitted pathogens can cause similar signs and symptoms.
Diagnosis consultant for numerous US-based and international
is particularly challenging in men, where infections are characterised by
clinical, epidemiological and public health research projects. Dr Hobbs earned her degree
from Duke University.
fewer organisms than infections in women.
In this report, we review
the performance characteristics, advantages and limitations of currently
available T. vaginalis detection methods. Arlene C Seña is a Clinical Associate Professor of Medicine
in the Division of Infectious Diseases at the University of
North Carolina at Chapel Hill and the Medical Director of
the Durham County Health Department in Durham, North
In clinical practice, laboratory diagnosis of trichomoniasis has previously
Carolina. Her research interests include the epidemiology,
diagnosis and treatment of sexually transmitted infections,
relied on microscopic examination of a wet-mount preparation of vaginal
specifically Trichomonas vaginalis and syphilis, and HIV
discharge or male urine sediment. Because of the characteristic shape and prevention. She has been involved in public health for over
unique tumbling motility of live T. vaginalis in such preparations, wet-mount
10 years, and served as a prevention fellow with the
Centers for Disease Control and Prevention (CDC) Division of STD Prevention, Epidemiology
microscopy is assumed to have perfect specificity. In expert hands,
and Surveillance Branch. Dr Sena earned her medical doctorate and masters in public health
wet-mount microscopy can be 50–70% sensitive in specimens from
from the University of North Carolina at Chapel Hill.
women, but the technique is much less reliable in specimens from men.
© TOUCH BRIEFINGS 2007 39
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