Tropical Parasitology

: 2011  |  Volume : 1  |  Issue : 2  |  Page : 73--75

Trichomoniasis: An update

V Preethi1, Jharna Mandal1, Ajay Halder2, Subhash Chandra Parija1,  
1 Department of Microbiology, JIPMER, Puducherry, India
2 Department of Gynaecology, Christian Medical College, Vellore, India

Correspondence Address:
Subhash Chandra Parija
Department of Microbiology, JIPMER, Puducherry-605 006


Trichomoniasis is one of the most common sexually transmitted infections (STIs) with a prevalence of 5-75%. In India, trichomoniasis accounts for 2-7% of all STIs. Infection with Trichomonas vaginalis is known to cause vaginitis. Significant association has also been noted between trichomoniasis and cervical cancer, atypical pelvic inflammatory disease, infertility, low birth weight, and respiratory-tract infection in neonates. Of interest are the recent documentations of association of this parasite with human immunodeficiency virus. Use of fluorescent dyes such as acridine orange has increased the sensitivity of the direct microscopy. Culture has been found to be more sensitive than the direct microscopy but has its own limitations. Antigen detection systems have hastened the proce ss of diagnosis tremendously. Molecular methods have been found to be very sensitive and specific. Once the presence of T. vaginalis has been documented, other STIs should also be actively looked for in that particular individual. Therapy should involve both the partners for proper control and eradication of the disease.

How to cite this article:
Preethi V, Mandal J, Halder A, Parija SC. Trichomoniasis: An update.Trop Parasitol 2011;1:73-75

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Preethi V, Mandal J, Halder A, Parija SC. Trichomoniasis: An update. Trop Parasitol [serial online] 2011 [cited 2022 Jun 28 ];1:73-75
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Trichomoniasis is one of the most common sexually transmitted infections (STIs) but it has received little attention and has been trivialized. It is estimated that 170 million cases of vaginal trichomoniasis occur annually worldwide. [1] The prevalence is widely variable ranging from 5% in family planning clinics to 50-75% in sexually transmitted disease (STD) clinics. [1] The prevalence is widely variable ranging from 5% in family planning clinics to 50-75% in STD clinics. [1],[2] In India, trichomoniasis accounts for 2-7% of all STIs. [3],[4],[5]

A recent interest in the diagnosis and control of the disease was after its association with premature births and increased risk of Human immunodeficiency virus (HIV) infection in patients with trichomoniasis. [1],[6] There have been several studies in Africa, which have shown that trichomoniasis increases the risk of HIV transmission. Both diseases have similar modes of acquisition. The increased risk of HIV in a patient with trichomoniasis could be due to the presence of inflammatory cells harboring the virus and the minor abrasions on the genital mucosa due to the STD could facilitate HIV virus transmission. [6] However, HIV infection does not make a woman more likely to have prevalent, incident, or persistent or recurrent trichomoniasis. [7]

Leroy et al. studied the incidence and prevalence of STDs in HIV positive pregnant women in Rwanda. They found that HIV significantly increased the risk of trichomoniasis and also that there is an increased risk of relapse in treated women of this group. [8]

Not only is its association with adverse outcomes is being increasingly studied, but also whether effective treatment would thwart these outcomes. Adequate treatment has been shown to decrease the vaginal HIV RNA levels. However, high-dose metronidazole in pregnancy has been shown to increase the risk of preterm delivery. [9]

Trichomoniasis has also been linked to cervical cancer, atypical pelvic inflammatory disease, and infertility. [10] Low birth weight and neonatal infection is known to occur. Infection with Trichomonas vaginalis has been documented to cause vaginitis and respiratory tract infection in neonates. [11]

Trichomoniasis can be asymptomatic in nearly 50% of the infected women or the patients may present with a wide variety of symptoms. [5] T. vaginalis causes cervicitis and vaginitis in females and urethritis in both sexes. The infection, once established, persists for long periods in females but only for a short time in males. [10] Signs of infection include vaginal discharge and edema or erythema. Patients with T. vaginalis infection have vulval irritation and present with copious purulent vaginal discharge. The discharge, which is classically described as frothy is actually so only in about 10% of patients. [5] On examination, vulval erythema and punctate hemorrhagic spots in the cervix and vagina ("strawberry cervix") are characteristically seen. However, these symptoms and signs have a low sensitivity and low positive predictive value. [11]

The samples used for diagnosis include vaginal or urethral secretions collected using charcoal impregnated swabs. If urine is used as a sample, a centrifuged deposit is taken in a swab. The simplest and most rapid method is direct microscopy of unstained wet preparations in which the actively moving organism is easily recognized. However, the wet mount examination should be done within 20 min of collection as the organisms may lose their viability. [5] The sensitivity of this technique varies from as low as 38% to as high as 82%. [10] Since performance of direct microscopy is not always possible due to the heavy patient load, permanent stains such as papanicolaou and giemsa can be used. Direct wet mount microscopy, though not very sensitive, is still being widely used due to its economy and its ease of use. Use of other tests like rapid tests and culture to test samples negative by wet mount is also being followed to increase sensitivity. [12]

Fluorescent dyes such as acridine orange (AO) can also be used in the diagnosis of trichomoniasis. AO is a fluorescent nucleic acid stain, which stains T. vaginalis a characteristic brick-red color with an oval yellow-green nucleus. [13]

The broth culture method was considered the "gold standard" for the diagnosis of trichomoniasis because it is simple to interpret and requires as few as 300 to 500 trichomonads/ml of inoculum. [10] Culture has a higher sensitivity than wet mount of 75-85% and a specificity of 100%. [12] Media used Diamond's medium, Feinberg and Whittington's medium, cysteine-peptone-liver-maltose (CPLM). Cultures are examined after incubation at 36°C for 3 and 6 days, using microscopy of wet preparations. Culture for TV is a relatively inexpensive option, but it requires rapid sample transport or on-site incubation and is also time consuming. To improve usability and yield, InPouch system was introduced. It is a two-chambered bag that allows one to perform an immediate wet-mount by microscopic examination through the bag, as well as a culture. [10]

Cell culture using McCoy cells has been shown to be more sensitive than wet mount or broth culture detecting as few as three organisms/ml but the use of cell cultures is cumbersome and not routinely performed. [10]

Serological diagnosis by agglutination, complement fixation, indirect hemagglutination, gel diffusion, fluorescent antibody, and enzyme-linked immunosorbent assay has been used to demonstrate the presence of antitrichomonal antibodies. Since trichomonal antibodies may persist for a long time after treatment, current and past infections cannot be distinguished by these tests. Monoclonal antibodies to immunogens such as the 62- and 65-kDa proteins for the detection of T. vaginalis from clinical specimens have been shown to give similar results as wet-mount preparations. [10]

Recently, rapid tests like the lateral flow assay for detection of trichomonal antigens including the membrane protein. These point-of-care tests are said to be as sensitive and specific as culture (85-90% sensitive and 100% specific). [12] Their ease of use and rapid results are their major advantages over culture. It was also found that in samples whose transport to the laboratory or wet mount examination was delayed over 50 min, the rapid tests still remained positive unlike culture as the rapid tests do not require viable or morphologically intact trophozoites. [12]

Diagnosis by molecular methods like the polymerase chain reaction (PCR) is considered superior to wet mount and culture for the diagnosis of trichomoniasis. The sensitivity ranges from 91-99% and specificity of PCR ranges from 96-100%. [14] The various genes that can be targeted include multiple genomic loci or repeated, dispersed DNA of T. vaginalis, adhesion gene, beta tubulin, or Tv E60 repetitive sequence of T. vaginalis. [15] The sensitivity of PCR was so high that even the presence of a single trophozoite is said to result in a positive PCR. [15] The use of molecular methods helps detect nonviable organisms and also has the ability to detect cells and target sequences in clinical samples that have undergone fixation or partial degradation. [16] Dot blot hybridization and fluorescence in situ hybridization techniques have also been used in the diagnosis of trichomoniasis. [10]

The presence of T. vaginalis could also indicate the presence of other organisms such as Neisseria gonorrhoeae or Chlamydia trachomatis, (15-28% chlamydial coinfection and 10% gonorrhoeal coinfection rates) which have widely recognized clinical implications especially in pregnancy. Therefore, the presence of T. vaginalis could constitute a marker for the presence of other sexually transmitted infectious agents. [11],[16] There has been a negative association with Lactobacillus, suggesting that lactobacilli could be protective against trichomoniasis but this has not been statistically proven. [11]

The treatment of trichomoniasis is metronidazole, prescribed as a single 2 g oral dose or as a 7-day course of 500 mg b.i.d., with an expected cure rate of 90%. [1] Trichomonal resistance to metronidazole was reported within 2 years of its introduction but high-level resistance to metronidazole is extremely rare. Low-level in vitro resistance is also uncommon, but patients with low-level in vitro resistance may be cured with conventional divided-dose metronidazole therapy given for 7 days (total dose, 7 g). High-dose systemic and vaginal tinidazole has been successful in eradicating severe clinically metronidazole-resistant vaginal trichomoniasis. Another successful alternative is topical paramomycin. [1]


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