Chapter 57 Sexually Transmitted Infections: Trichomonas Vaginalis
INTRODUCTION
Description: Infection by the anaerobic flagellate protozoan, Trichomonas vaginalis is most often acquired by sexual contact with an infected person.
ETIOLOGY AND PATHOGENESIS
Risk Factors: Multiple sexual partners, vaginal pH that is less acidic. (Blood, semen, or bacterial pathogens increase the risk.) Of asymptomatic partners of women with Trichomonas infections, 30% to 80% have a positive culture. The incubation period for Trichomonas infections is thought to be between 4 and 28 days. Trichomonas has been reported (rarely) in virginal patients, supporting the possibility of nonsexual transmission.
CLINICAL CHARACTERISTICS
DIAGNOSTIC APPROACH
Workup and Evaluation
Laboratory: Culture or monoclonal antibody staining may be obtained but are seldom necessary. Evaluation for concomitant sexually transmitted infections should be strongly considered. Detection of Trichomonas by Pap test results in an error rate of 50%. (Alternative tests include OSOM Trichomonas Rapid Test [Genzyme Diagnostics, Cambridge, Massachusetts], an immunochromatographic capillary flow dipstick technology, and the Affirm VP III [Becton Dickinson, San Jose, California], a nucleic acid probe test that evaluates for T. vaginalis, Gardnerella vaginalis, and Candida albicans. These tests have a sensitivity of >83% and a specificity of >97%, although false-positive results are common when prevalence is low.)
