AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Trichomoniasis is a nonreportable sexually transmitted disease caused by the parasite Trichomonas vaginalis. Humans are the only known host with the trophozoite transmitted via coitus. Reports also exist of transmission via fomites. The organisms are usually pyriform in shape, although they may take an amoeboid shape after attachment to the vaginal epithelium. The individual organism is slightly larger (9X7 µm) than a white blood cell. Four flagella project from the anterior portion of the cell.

Pathophysiology

T vaginalis principally infects the squamous epithelium of the genital tract. Incubation time is generally between 4 and 28 days. Infection may persist for long periods in females, but generally persists less than 10 days in males. Anecdotal evidence suggests that asymptomatic infection may persist for months or even years in women.

In females, vaginitis is the most common manifestation of infection. Other complications include infection of the adnexa, endometrium, and Skene and Bartholin glands. Males are usually asymptomatic. When symptoms are present, they usually manifest as urethritis. Up to 11% of nongonococcal urethritis cases are caused by T vaginalis. Other complications include infection of the prostate, foreskin, glans, and epididymis.

Infection with T vaginalis is a marker of high-risk sexual behavior. Co-infection with other STDs is common. In one study of adolescents who had a diagnosis of at least one STD, there was almost a 9-fold increase in the likelihood of T vaginalis infection in the ensuing 3 months.

Infection produces immunity that at best is only partially protective. Evidence of lymphocyte priming is shown by the presence of antigen-specific peripheral blood mononuclear cells. An antibody response locally and in serum has also been detected. Despite the interaction that the human immune system has with T vaginalis, little evidence exists that it prevents infection. One study showed no association between trichomoniasis and the use of protease inhibitors or immune status in women with HIV. Another study showed that HIV seropositivity does not alter the rate of infection.

Frequency

United States

An estimated 7.4 million new cases of trichomoniasis occur per year in the United States. Exact numbers are difficult to obtain because the infection is not nationally reportable. Prevalence is also typically underestimated due to the poor sensitivity of diagnostic tests. The reported prevalence in inner city STD clinics approaches 25%.

International

The World Health Organization estimates that 180 million new cases of trichomoniasis occur each year.

Mortality/Morbidity

• Trichomoniasis is commonly associated with co-infection with other STDs, especially Neisseria gonorrhoeae.
• Infection with T vaginalis may increase the rate of infection or reactivation with human papilloma virus, although it may shorten the duration of infection.
• Trichomoniasis predisposes one to infection with HIV. Infection with HIV increases one's infectiveness for transmitting T vaginalis.
  • Cheeson et al estimates that 747 new HIV cases a year in women alone are a result of the facilitative effects of T vaginalis on the transmission of the HIV virus.
  • Symptomatic males with T vaginalis and HIV had significantly higher numbers of HIV RNA particles in their seminal fluid.
  • Wang et al showed that treatment of T vaginalis resulted in a 4.2-fold reduction in the number of HIV viral particles in vaginal specimens.
• The Vaginal Infections and Prematurity (VIP) Study showed an increased risk of low birth weight, preterm delivery, and preterm delivery of a low birth weight baby.
• The National Institute of Child Health and Human Development Maternal Fetal Medicine Units Network presented data that suggest that metronidazole treatment of asymptomatic carriers of T vaginalis increased risk of preterm birth. This is a controversial conclusion, as the study design did not accurately reflect clinical practice. The investigators used 4 doses of 2 g metronidazole in the treatment of infection, which is significantly higher than what is standard practice. The women included in the study were between 16 and 23 weeks' gestational age, suggesting a significant delay in treatment.
• Increased risk of PID is shown in HIV-positive women.
• Increased risk of posthysterectomy infection including cuff cellulitis, cuff abscess, and wound infection is present.
• Association with cervical intraepithelial neoplasia is noted.
• In males, a risk exists of epididymitis, prostatitis, and decreased sperm cell motility.

Race

• In an analysis of National Longitudinal Study of Adolescent Health (Add Health), Miller et al presented the prevalence of trichomoniasis among adolescents. Significant differences existed among races: white, 1.2%; Latino, 2.1%; black, 6.9%; Asian, 1.8%; and Native American, 4.1%.

Sex

• Trichomoniasis is more common in women than in men.
• The incidence in males has been reported in varying populations to be between 2.8 and 17%. This may be underestimated due to the method of detection and the site of specimen collection. Use of multiple sites of the genitourinary tract in males has been shown to increase sensitivity.

Age

• Vertical transmission of T vaginalis during birth is possible and may persist up to 1 year. From 2 to 17% of female offspring of infected women acquire infection.
• Unlike other STDs, the incidence of trichomoniasis increases with age.
  • The Add Health Study found that the prevalence among adolescents aged 18-24 years was 2.3%. For adults 25 years and older, the prevalence was 4%.
  • In a study by Joyner et al of 454 men attending an STD clinic in Denver, the prevalence in men younger than 30 years was 0.8%, and for men 30 years and older, the prevalence increased to 5.1%. This difference was thought to be due to age-related enlargement of the prostate gland.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

• Nearly half of infected women and almost all infected males are asymptomatic.
• Presenting signs and symptoms may include vaginal or urethral discharge, odor, irritation, itch, dysuria, abdominal pain, and dyspareunia.
• One third of asymptomatic women become symptomatic within 6 months.
• Males are divided into 3 groups: asymptomatic carrier state, acute trichomoniasis, and mild symptomatic disease.

Physical

• Vaginal discharge is found in 42% of infected women.
• • The discharge is classically described as thin and frothy; however, this is only seen in about 10% of patients.
  • The discharge is often yellow. Sometimes, it is thick enough to be confused with candidiasis.
• Abnormal vaginal odor was found in 50% of infected women.
• Edema or erythema was found in 22-37% of infected women.
• Vaginal pH is often elevated (>4.5).
• Colpitis macularis (strawberry cervix) is the finding of punctate hemorrhages and occasionally vesicles or papules on the cervix. It is the most specific clinical sign for the diagnosis of trichomoniasis. It is rarely detected without colposcopy.
• In males, if symptomatic, usually only scant, thin discharge, which is worse in the morning, is present.
• The clinician's ability to accurately diagnose T vaginalis infection based on physical alone was shown to have a positive predictive value of only 42%.

Causes

Trichomoniasis is caused by the flagellated protozoan T vaginalis.

• Risk factors for T vaginalis include the following:
• • Infection with other STDs, especially gonorrhea
  • Four or more lifetime sex partners
  • Sexual contact with an infected partner
  • Not using barrier contraception
  • Trading sex for money or drugs

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Foreign body vaginitis
Allergic vaginitis
Chemical vaginitis
Cervical, vulvar, or vaginal neoplasia
Infection with Mycoplasma hominis

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Given the poor reliability of history and physical for the diagnosis of trichomoniasis, laboratory tests are of increased importance. Most clinics and hospitals do not have these tests available. Of 100 public health laboratories responding to a survey, only 6 reported performing testing for trichomoniasis. None of those responding reported using any of the newer techniques for detection.
• Whiff test
• • Perform the amine odor test by mixing several drops of 10% potassium hydroxide (KOH) to a sample of vaginal discharge. A strong fishy odor is indicative of a positive result.
  • This test may be positive for either trichomoniasis or bacterial vaginosis. This test should not be considered an accurate means of diagnosis for trichomoniasis. It is one of the four parts of Amsel's Criteria used to diagnose bacterial vaginosis.
• Whiff test and pH testing have been combined in the QuickVue Advance pH and Amines test. This test uses Layered Thin Film technology. The results are read within 2 minutes.
• Wet mount
• • The procedure is performed by placing a small amount of vaginal discharge on a microscope slide and mixing with a few drops of saline solution. The slide is then examined under a microscope at low or medium power.
  • The presence of flagellated, pyriform protozoa indicates a positive result.
  • Slides must be read within 20 minutes of obtaining sample due to loss of characteristic motility of the trichomonads.
  • Sensitivity is poor, 40-60%.
  • Sensitivity may be increased using cervical vaginal lavage. In this modification, 5 mL of sterile saline is injected toward the cervix. Using a pipette, the cervix is bathed 2-3 times prior to drawing up the fluid from the posterior vaginal fornix. Sensitivity was increased to 74.4% versus 54.7% for vaginal swab alone.
  • A short downloadable video can be seen at Seattle STD/HIV Prevention Training Center.
• Papanicolaou smear: Sensitivity is similar to that of wet mount, 60%.
• OSOM Trichomonas Rapid Test
• • This test uses color immunochromatographic "dipstick" technology with murine monoclonal antibodies.
  • Results are read within 10 minutes.
  • Freezing and transportation of specimens do not appreciably alter the test results.
  • In a comparison to a composite reference standard of wet mount microscopy and culture, the sensitivity was 83.3% and specificity was 98.8%.
• XenoStrip-Tv T vaginalis test
• • This test detects T vaginalis-specific antigen by color immunochromatographic "dipstick" technology with mouse antibodies bound to a nitrocellulose membrane.
  • Results are read at 10 minutes.
  • In a comparison to an expanded criterion standard of positive wet mount and PCR, the sensitivity was 66.6% and specificity was 100%.
• BD Affirm VPIII Microbial Identification Test
• • This test uses nucleic acid hybridization technology.
  • Tests for the presence of Trichomonas, Gardnerella, and Candida species.
  • In this procedure, the sample is treated with lysis solution and heated. This ruptures the walls of the organisms present and releases their nucleic acid. Buffer solution is then added to stabilize the nucleic acid. The sample is then added to the first well of the reagent cassette along with the probe analysis card. Hybridization to the capture probe occurs in this first well. In the second well, hybridization to the color development probe occurs. Unbound specimen is washed away in well 3. In the next well, enzyme conjugate binds to the hybridized nucleic acid. In the next two wells, the unbound enzyme conjugate is washed away. In the last well, the indicator substrate is converted to a blue-colored product if bound enzyme conjugate is present on the bead.
  • Sensitivity is between 90 and 100%.
• Culture
• • Culture is typically performed in Diamond medium.
  • InPouch Tv test procedure
  • • InPouch is a combined wet mount and culture kit.
    • The clinician inoculates the upper chamber of the pouch with a cotton swab. The pouch can be kept at room temperature for up to 18 hours without significant alteration of sensitivity.
    • In the laboratory, a viewing clamp is placed across the upper chamber and examined under a microscope at 100X magnification. If no trichomonads are viewed, the bottom chamber is inoculated using the medium from the upper chamber. The InPouch is incubated at 37°C and viewed at regular intervals.
    • Sensitivity approaches 100%.
    • As few as one parasite in the sample may be detected.
    • Samples taken during menses were not adversely affected.
• Polymerase chain reaction
• • PCR is based on DNA amplification and detection using known primers to Tv specific genes.
  • PCR is used for research purposes only.
  • BTUB 9/2 - Encodes for beta-tubulin amino acid; sensitivity 97%, specificity 98%
  • TV1/TV2 - Encodes for 18S subunit of T vaginalis ribosomal RNA; sensitivity 100%, specificity 98%
  • In males, performing PCR on urine sediment rather than urethral swabs improves detection rates.
  • First void urines have improved sensitivities.

Other Tests

• Patients should also be tested for other STDs.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Emergency Department Care

Trichomoniasis is usually diagnosed in outpatient or emergency department settings. Treatment should be instituted immediately and when possible in conjunction with all sexual partners. Because of the high co-infection rate with other STDs, the healthcare provider should consider empiric treatment for gonorrhea and chlamydia. Patients should also be offered counseling and testing for HIV.

Consultations

For patients with treatment failure and in whom reinfection is ruled out, the Centers for Disease Control and Prevention Sexually Transmitted Diseases Treatment Guidelines 2002 can be consulted (telephone: 770-488-4115).

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Nitroimidazoles are a class of drugs used to fight a variety of parasitic and anaerobic bacterial infections. The drug is taken up by target organisms and reduced to its active form. The reduced drug then disrupts the helical structure of the DNA within these microbes preventing nucleic acid synthesis and eventually leading to cell death.

A number of clinical trials and meta-analyses have not demonstrated teratogenic effects of metronidazole. The CDC currently recommends that symptomatic pregnant females be treated with the standard single-dose regimen of 2 g metronidazole orally.

Patients allergic to this class of drug should be referred for desensitization.

Clotrimazole vaginal tablets have been used in the past. In a study by DuBouchet et al in 1997, only an 11% cure rate was noted with this mode of therapy.

Drug Category: Antiprotozoals

These agents may bind DNA and inhibit protein synthesis, causing cell death. In the drug tinidazole, the free nitro radical generated during metabolism is thought to be responsible for antiprotozoal. However, the exact mechanisms of many antiprotozoal agents are not well understood.

Drug Name	Tinidazole (Tindamax)
Description	5-nitroimidazole derivative used for susceptible protozoal infections. 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. Single-dose therapy of 2 g taken with food. Cure rates from 83-100%. Available outside US for more than 25 years. Approved by the FDA in May 2004. Has a longer half-life (12-14 h) than metronidazole (6-7 h). In a case series by Hager et al, all 3 patients who failed 3 regimens of metronidazole therapy were cured by tinidazole.
Adult Dose	Individual and sexual partner: 2 g PO once ac
Pediatric Dose	Adolescents: 1.5 g PO once ac
Contraindications	Documented hypersensitivity; first trimester of pregnancy
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
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Pregnancy category X in first trimester of pregnancy; caution in blood dyscrasias, organic neurologic dysfunction, late trimesters of pregnancy, seizure disorders, and hepatic and renal impairment Carcinogenicity has been observed in mice and rats treated chronically with metronidazole (another nitroimidazole), although not observed with tinidazole, use cautiously; 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

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Further Outpatient Care

• Patients who become asymptomatic or are asymptomatic to begin with do not require routine follow-up.

Deterrence/Prevention

• Condom use may be protective.

Complications

• See Pathophysiology.

Prognosis

• Recurrent infections occur in 30% of patients.

Patient Education

• Upon diagnosis, discuss the importance of treatment and treatment of partners with the patient. Discuss methods of prevention. It may also be important to explain that the infection may have been long-standing and not due to a recent encounter.
• For patient education resources, see the Trichomoniasis CDC Fact Sheet.
• For excellent patient education resources, visit eMedicine's Parasites and Worms Center. Also, see eMedicine's patient education article Trichomoniasis and Sexually Transmitted Diseases.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Failure to recognize the infection may result in complications in pregnancy. The medicolegal implications are unclear as it has not been demonstrated that treatment of trichomoniasis reduces the incidence of complications.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

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Article Last Updated: Mar 27, 2006