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Trichomoniasis
Article Last Updated: Aug 20, 2008
AUTHOR AND EDITOR INFORMATION
Section 1 of 13  
Author: D Scott Smith, MD, MSc, DTM&H, Adjunct Assistant Professor, Department of Microbiology and Immunology, Stanford University; Chief of Infectious Diseases and Geographic Medicine, Department of Internal Medicine, Kaiser Redwood City Hospital
D Scott Smith is a member of the following medical societies: American Medical Association, American Society of Tropical Medicine and Hygiene, Infectious Diseases Society of America, and International Society of Travel Medicine
Coauthor(s):
Natalia Ramos, BA, Stanford University, Keck School of Medicine of the University of Southern California
Editors: Jeffrey M Zaks, MD, Clinical Associate Professor of Medicine, Wayne State University School of Medicine; Vice President, Medical Affairs, Chief Medical Officer, Department of Internal Medicine, Providence Hospital; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; John L Brusch, MD, FACP, Assistant Professor of Medicine, Harvard Medical School; Consulting Staff, Department of Medicine and Infectious Disease Service, Cambridge Health Alliance; Eleftherios Mylonakis, MD, Clinical and Research Fellow, Department of Internal Medicine, Division of Infectious Diseases, Massachusetts General Hospital; Burke A Cunha, MD, Professor of Medicine, State University of New York School of Medicine at Stony Brook; Chief, Infectious Disease Division, Winthrop-University Hospital
Author and Editor Disclosure
Synonyms and related keywords:
trichomoniasis, Trichomonas vaginalis, T vaginalis, vaginal trichomoniasis, trichomonads, nongonococcal nonchlamydial urethritis, prostatitis, epididymitis, urethral stricture disease, pelvic inflammatory disease, colpitis macularis, vaginal discharge, vaginitis, cervicitis, dyspareunia, dysuria
Background
Trichomoniasis is a sexually transmitted infection caused by the protozoa Trichomonas vaginalis. It is one of the most common sexually transmitted diseases in the United States.1 Women with trichomoniasis may experience various symptoms, including a yellow-green vaginal discharge and vulvar irritation, or they may be asymptomatic. Men with trichomoniasis are frequently asymptomatic.2 The high incidence of trichomoniasis worldwide, its contribution to poor health outcomes, and its co-infection with other sexually transmitted infections make trichomoniasis a compelling public health concern. Notably, T vaginalis infection is believed to increase the risk of HIV transmission.1 Trichomoniasis is also associated with adverse pregnancy outcomes, infertility, postoperative infections, and cervical neoplasia.3
Pathophysiology
T vaginalis is approximately the size of a white blood cell (about 10 μm in diameter), although its size may vary with physical conditions. Its flagellum allows it to move around vaginal and urethral tissues. T vaginalis directly damages the epithelium, leading to microulcerations of inhabited tissues, increasing the risk of HIV transmission.1
Symptoms of trichomoniasis typically occur after an incubation period of 4-28 days. In women, T vaginalis is isolated from the vagina, cervix, urethra, bladder, and Bartholin and Skene glands. In men, the organism is found in the anterior urethra, external genitalia, prostate, epididymis, and semen.
Frequency
United States
Approximately 8 million new cases of trichomoniasis occur annually.4 The prevalence of T vaginalis infection at clinics that treat STDs varies from 15-54%.5 In men, trichomoniasis accounts for 10-21% of urethritis cases not attributable to gonorrheal or chlamydial infection.5
International
Worldwide, the annual incidence of trichomoniasis is about 170 million cases.6 The incidence of trichomoniasis in Europe is similar to that in the United States. In Africa, the prevalence of trichomoniasis may be much higher.
Mortality/Morbidity
T vaginalis infection is highly associated with the presence of other sexually transmitted infections, including gonorrhea, chlamydia, and HIV. Persons with trichomoniasis are twice as likely to develop HIV infection as the general population.7 Two explanations exist for the association between T vaginalis and HIV: (1) Disruption of the epithelial monolayer leads to increased passage of the HIV virus; (2) T vaginalis induces immune activation, specifically lymphocyte activation and replication and cytokine production, leading to increased viral replication in HIV-infected cells.
Pregnant women with T vaginalis infection are more likely than uninfected women to deliver preterm or to have other adverse pregnancy outcomes, including low birth weight, premature rupture of membranes, and intrauterine infection.1 However, whether trichomoniasis causes the adverse outcome is unclear.1 T vaginalis infection may also increase the transmission of HIV owing to disruption of the vaginal mucosa. Respiratory or genital infection in the newborn should also be considered.2
One study reported a higher risk of pelvic inflammatory disease in women with trichomoniasis.8 Other studies have reported a 1.9-fold risk of tubal infertility in women with trichomoniasis.9 Trichomoniasis may also play a role in cervical neoplasia and postoperative infections.3
In men, complications of untreated trichomoniasis include prostatitis, epididymitis, urethral stricture disease, and infertility. Infertility may result from a decreased sperm motility and viability.3
See the Clinical section for presenting symptoms and signs.
Sex
Symptomatic trichomoniasis is more common in women than in men. Trichomoniasis infection in men is less clinically apparent.
Age
Trichomoniasis is a sexually transmitted infection. As such, it is typically found in sexually active adolescents and adults.
History
Women
Trichomoniasis symptoms in women range from none to severe pelvic inflammatory disease. Women with trichomoniasis frequently report a frothy yellowish-green vaginal discharge, abnormal vaginal odor, vulvovaginal itching and soreness, dyspareunia (pain during sexual intercourse), and dysuria (pain during urination). However, many infected women experience no symptoms.
Cervicitis due to trichomoniasis is characterized by 2 major signs—purulent discharge in the endocervical canal and easily induced endocervical bleeding.2 However, it may also be asymptomatic.
T vaginalis infection is one of the top 3 causes of vaginitis.2 Vaginitis is usually characterized by vaginal discharge, which may be accompanied by vulvar itching, irritation, and odor. The two other most common causes of vaginal discharge are anaerobic bacterial overgrowth of normal flora and candidiasis (infection with Candida albicans).2
Men
Trichomoniasis symptoms in men range from none to urethritis complicated by prostatitis. Nongonococcal nonchlamydial urethritis is the most common symptom reported by men with trichomoniasis. Symptoms of urethritis include discharge, dysuria, and urethral pruritus.2 The discharge may be purulent to mucoid in character. Most symptomatic infections are intermittent and self-limiting. Complications of untreated trichomoniasis include prostatitis, epididymitis, urethral stricture disease, and infertility.
Physical
Women
- Purulent or homogenous vaginal discharge and vulvar or vaginal erythema are common.
- Colpitis macularis, or strawberry cervix, describes a diffuse or patchy macular erythematous lesion of the cervix. This is a specific sign for trichomoniasis but is visible in only 1-2% of cases without the aid of colposcopy. With colposcopy, colpitis macularis is detected in up to 45% of cases.
- Lower-abdominal tenderness may be present; however, this is described in fewer than 10% of patients. If this occurs, coexisting salpingitis or an intra-abdominal pathology is possible.
- Coexisting Neisseria gonorrhea infection, candidiasis, and bacterial vaginosis are common and may produce a mixed clinical picture.
Men - The findings of trichomoniasis in men on physical examination are generally unremarkable unless the infection is complicated. It may be associated with local inflammatory states, including balanitis and balanoposthitis.
- Physical findings of epididymitis and prostatitis may also occur.
Causes
See Pathophysiology.
Appendicitis
Balantidiasis
Candidiasis
Chlamydial Genitourinary Infections
Cystitis, Nonbacterial
Epididymitis
Gonococcal Infections
Nonbacterial Prostatitis
Pelvic Inflammatory Disease
Urethritis
Vaginitis
Other Problems to be Considered
Bacterial vaginosis
Atrophic vaginitis with secondary infection
Erosive lichen planus
Foreign-body vaginosis
Lab Studies
Laboratory studies aid in demonstration of the T vaginalis organism and are used to differentiate trichomoniasis from bacterial or fungal infection. Saline microscopic examination - Vaginal trichomoniasis is typically diagnosed with microscopy. A vaginal swab sample for saline wet mount evaluation is an easy, valuable, and economical tool, but specificity is limited and the slide should be evaluated immediately.2
- Trichomonads, which are ovoid-shaped parasites, are slightly larger than polymorphonuclear lymphocytes (PMNs) and may be identified by their ameboid mobility. Trichomonads cause an inflammatory reaction; therefore, a large number of PMNs are usually present and correlate with the severity of the infection.
- Microscopy yields a sensitivity of 60-70% in the detection of T vaginalis in vaginal secretions.2 The absence of trichomonads on microscopy does not exclude the possibility of trichomoniasis.
pH testing
- In women with trichomoniasis, the pH of vaginal secretions measured on Nitrazine paper is often elevated (>4.5). However, an elevation in pH is not highly specific. Bacterial vaginosis frequently also elevates the pH.2
- Upon application of 10% potassium hydroxide to a vaginal swab sample in the potassium hydroxide (KOH) amine test, a fishy odor is released, which can suggest trichomoniasis or bacterial vaginosis.
Standard culture - Culture is more sensitive and specific than microscopy.2 Culture yields a sensitivity of about 95%.6
- Disadvantages of culture method include testing time and availability.5
- Swab is put in broth and incubated anaerobically at 37°C. Growth is usually detected within 48 hours, and samples without growth after 7 days are considered negative for trichomoniasis.6
- Culture is especially important for diagnosing trichomoniasis in men since the wet preparation findings are usually negative. Urethral swab, urine, and semen cultures are used to maximize sensitivity.2
Papanicolaou (Pap) smear - Trichomonads may be viewed on Papanicolaou (Pap) smear, but this test yields low sensitivity and should not be relied on for diagnosis (50%). False-positive results are also common with this technique.5
Polymerase chain reaction (nucleic acid amplification) - Polymerase chain reaction (PCR) methods yield a high sensitivity (84%) and specificity (94%). Although not yet widely available, PCR has great diagnostic potential.5
Other Tests
Other Food and Drug Administration (FDA)–approved tests for diagnosing trichomoniasis in women include the OSOM Trichomonas Rapid Test (an antigen-based test) and the Affirm VP III (a DNA probe). These tests offer results within 10 and 45 minutes, respectively. Both are more sensitive than wet mount yet less sensitive and specific than culture.2
Histologic Findings
Trichomonads may be observed in a saline wet mount of a vaginal swab or secretion in approximately 60-70% of women with trichomoniasis.2 Trichomonads are ovoid in shape and slightly larger than PMNs. They are identifiable by to their ameboid mobility. Because they cause an inflammatory reaction, a large number of PMNs are usually present, correlating with the severity of the infection.
Medical Care
- Prompt trichomoniasis diagnosis is important for eliminating infection in the patient and sexual partners.
- Treatment of sexual partners is thought to increase cure rates.2
- Systemic treatment is important to ensure a cure, as trichomoniasis is an infection of multiple sites (eg, vaginal epithelium, Skene glands, Bartholin glands, urethra).
- Oral metronidazole is the treatment of choice and has been demonstrated in multiple studies to offer efficacy that is superior to that of intravaginal treatment.
- Drug resistance is rare, despite the prevalent use of nitroimidazole drugs in the treatment of trichomoniasis. Treatment failures may require a higher dose metronidazole regimen or the use of a different nitroimidazole.1
- In clinical practice, repeat testing is rarely performed unless symptoms do not improve with drug treatment. Theoretically, repeat testing at 5-7 and 30 days is recommended.1
- Routine screening for trichomoniasis in asymptomatic pregnant women is not currently recommended.2
Diet
Instruct the patient to avoid alcohol while taking metronidazole, tinidazole, or other nitroimidazole drugs. The interaction of the drugs and alcohol may cause a disulfiramlike reaction.
Activity
Patients should avoid sex until drug therapy is completed and all symptoms have disappeared.2 Treatment of the patient’s partner is crucial to avoid reinfection.
The 5-nitroimidazole group of drugs includes antiprotozoal agents (metronidazole, tinidazole, nimorazole, carnidazole) used for the treatment of trichomoniasis. In the Cochrane treatment review, metronidazole and other nitroimidazole group drugs were found to have comparable efficacy in treating trichomoniasis.1 The mechanism of action is not well understood; however, anaerobic organisms preferentially reduce the 5-nitro group, and active metabolites likely interact with anaerobic bacterial and protozoal DNA.
Resistance to these drugs is rare despite their widespread use in the treatment of trichomoniasis and is typically solved by increasing the dose or switching to another nitroimidazole.1 When standard treatment regimens fail, metronidazole or tinidazole at 2 g PO for 5 days should be considered.2
Drugs may also be applied locally in the vagina or rectum, although oral treatment is usually preferred. Local intravaginal medications include clotrimazole, povidone-iodine, and nonoxynol-9 (N-9). Metronidazole may also be applied vaginally or rectally to reach therapeutic concentrations in the blood. Topical drugs other than nitroimidazoles yield low cure rates (<50%).
Drug Category: Antiprotozoal agents
Therapy must be comprehensive and should cover all likely pathogens in the context of this clinical setting.
| Drug Name | Metronidazole (Flagyl) |
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| Description | This medication is available PO, IV, and as intravaginal suppository gel. Highly effective in the treatment of many anaerobic bacterial and protozoal infections. Cure rates for trichomoniasis have been reported at 90-95% by the CDC. |
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| Adult Dose | 2 g PO as single dose or 500 mg PO bid for 7 d |
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| Pediatric Dose | 15 mg/kg/d PO tid for 7 d |
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| Contraindications | Documented hypersensitivity |
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| Interactions | Inhibits metabolism of warfarin and potentiates the anticoagulant effect; causes an intolerance to alcohol similar to disulfiram (therefore, avoid alcohol during treatment and for 24 h after administration); abdominal cramps, nausea, vomiting, headaches, and flushing occur when co-ingested with alcohol; cimetidine prolongs the plasma clearance by inhibiting metabolic enzymes; conversely, drugs that induce liver enzymes (eg, phenobarbital) may increase the elimination of metronidazole |
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| Pregnancy | B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
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| Precautions | Usually well tolerated; commonly encountered adverse effects are nausea, vomiting, anorexia, and a metallic taste in the mouth; most serious adverse effects involve the nervous system and are manifested as convulsions and peripheral neuropathy, which are rare unless large doses are administered for a prolonged period; drug is slowly impaired in patients with reduced hepatic function; reduce dose in patients with reduced hepatic function to prevent toxic levels from building in the plasma |
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| Drug Name | Tinidazole (Tindamax) |
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| Description | Nitroimidazole antiprotozoal agent. Nitro group is reduced by cell extract of Trichomonas. The free nitro radical generated is thought to be responsible for antiprotozoal activity against T vaginalis. Indicated to treat trichomoniasis caused by T vaginalis in both males and females. Cure rates for trichomoniasis have been reported at 86-100% by the CDC. |
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| Adult Dose | Treat individual and sexual partner: 2 g PO in a single dose with food |
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| Pediatric Dose | 50 mg/kg once; 2 g maximum |
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| Contraindications | Documented hypersensitivity; first trimester of pregnancy |
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| Interactions | Limited data exist; interaction information based on experience with other nitroimidazole derivatives (ie, metronidazole); may prolong PT when coadministered with warfarin; avoid alcoholic beverages and preparations containing ethanol or propylene glycol during and 3 d following administration (may cause disulfiramlike reaction); may increase serum levels of lithium, phenytoin, cyclosporine, tacrolimus, and fluorouracil; CYP450 inducers (eg, phenobarbital, rifampin, phenytoin) may increase elimination; CYP450 inhibitors (eg, cimetidine, ketoconazole) may decrease elimination; concurrent administration with cholestyramine may decrease oral bioavailability; oxytetracycline may antagonize effect |
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| Pregnancy | C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
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| Precautions | Carcinogenicity has been observed in mice and rats treated chronically with metronidazole (another nitroimidazole), although not observed with tinidazole, use cautiously; seizures and peripheral neuropathy have been reported; caution with history of blood dyscrasia; may cause metallic/bitter taste, nausea, anorexia, vomiting, weakness, fatigue, dizziness, or headache; if administered on day of hemodialysis, administer additional dose equivalent to one-half of recommended dose following dialysis |
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Further Outpatient Care
- Sexual partners of patients infected with trichomoniasis must be treated to prevent reinfection.
- Consider empiric treatment of other sexually transmitted infections that frequently coexist with trichomoniasis.
- Advise the patient to abstain from sexual intercourse until both the patient and partner have completed therapy and are asymptomatic.2
- Persistent treatment failures may require metronidazole susceptibility testing through the Centers for Disease Control and Prevention (CDC).
Deterrence/Prevention
- Abstinence from sexual intercourse prevents trichomoniasis.
- Limiting the number of sexual partners decreases the risk of trichomoniasis.
- Male condoms can protect against the transmission of trichomoniasis. Although the efficacy of female condoms is undefined, they may also provide some protection.2
- Diaphragms have been shown to protect against trichomoniasis but should not be used as the primary source of protection against HIV.2
- Spermicides that contain nonoxynol-9 are not recommended for the prevention of sexually transmitted diseases. Frequent use is associated with disruption of the genital epithelium, which may be associated with an increased risk of HIV infection and other sexually transmissible agents.2
Complications
Patient Education
- Persons with trichomoniasis who notify their partner of their infection help disrupt the transmission of trichomoniasis and other sexually transmitted diseases.2
- Discuss the side effects and interactions encountered with metronidazole and other nitroimidazole drugs.
- Education concerning sexually transmitted disease treatment and sexually transmitted infection prevention should be provided (see Deterrence/Prevention). For excellent patient education resources, visit eMedicine's Parasites and Worms Center and Pregnancy and Reproduction Center. Also, see eMedicine's patient education article Trichomoniasis.
Medical/Legal Pitfalls
- Trichomoniasis is not a nationally mandated reported sexually transmitted disease, although other sexually transmitted disease reporting requirements vary by state.2
- Failure to treat trichomoniasis during pregnancy may result in preterm birth or other adverse fetal outcomes.1 The mother should seek treatment during pregnancy. Transmission of trichomoniasis from an infected mother during delivery is rare but possible. An infected infant may present with fever. Young girls may present with vaginal discharge.
- Screen for sexually transmitted diseases in pregnant patients and treat appropriately.
Special Concerns
The use of metronidazole in the first trimester of pregnancy is traditionally avoided. Although the mechanism of action is unclear, parasite death due to large doses of the drug may lead to a release of toxic substances.2 Consider the benefits and risks in treating trichomoniasis in pregnant patients.
ACOG Committee on Practice Bulletins--Gynecology. ACOG Practice Bulletin. Clinical management guidelines for obstetrician-gynecologists, Number 72, May 2006: Vaginitis. Obstet Gynecol. May 2006;107(5):1195-1206.
Abramowicz M (ed.). Drugs for Parasitic Infections. The Medical Letter. Aug 2004.
Burtin P, Taddio A, Ariburnu O. Safety of metronidazole in pregnancy: a meta-analysis. ALYSIS. Feb 1995;172(2 Pt 1):525-9.
Guenthner PC, Secor WE, Dezzutti CS. Trichomonas vaginalis-induced epithelial monolayer disruption and human immunodeficiency virus type 1 (HIV-1) replication: implications for the sexual transmission of HIV-1. Infect Immun. Jul 2005;73(7):4155-60. [Full Text].
Nanda N, Michel RG, Kurdgelashvili G, Wendel KA. Trichomoniasis and its treatment. Expert Rev Anti Infect Ther. Feb 2006;4(1):125-35.
Thanks to Amy Cai, MD, for sharing patient samples and insights.
| Media file 1:
Trichomonas vaginalis on a saline wet mount at 40X on the microscope. Several motile parasites transit through the field, surrounded by white blood cells and squamous epithelial cells. |
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Media type: Video
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- Laga M, Manoka A, Kivuvu M, et al. Non-ulcerative sexually transmitted diseases as risk factors for HIV-1 transmission in women: results from a cohort study. AIDS. Jan 1993;7(1):95-102. [Medline].
- Moodley P, Wilkinson D, Connolly C, et al. Trichomonas vaginalis is associated with pelvic inflammatory disease in women infected with human immunodeficiency virus. Clin Infect Dis. Feb 15 2002;34(4):519-22. [Medline].
- Grodstein F, Goldman MB, Ryan L, et al. Relation of female infertility to consumption of caffeinated beverages. Am J Epidemiol. Jun 15 1993;137(12):1353-60. [Medline].
- ACOG Practice Bulletin. Clinical management guidelines for obstetrician-gynecologists, Number 72, May 2006: Vaginitis. Obstet Gynecol. May 2006;107(5):1195-1206. [Medline].
- Burtin P, Taddio A, Ariburnu O, et al. Safety of metronidazole in pregnancy: a meta-analysis. Am J Obstet Gynecol. Feb 1995;172(2 Pt 1):525-9. [Medline].
- Guenthner PC, Secor WE, Dezzutti CS. Trichomonas vaginalis-induced epithelial monolayer disruption and human immunodeficiency virus type 1 (HIV-1) replication: implications for the sexual transmission of HIV-1. Infect Immun. Jul 2005;73(7):4155-60. [Medline]. [Full Text].
- Nanda N, Michel RG, Kurdgelashvili G, et al. Trichomoniasis and its treatment. Expert Rev Anti Infect Ther. Feb 2006;4(1):125-35. [Medline].
Trichomoniasis excerpt Article Last Updated: Aug 20, 2008
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