Trichomonas vaginalis

Trichomonas vaginalis is an anaerobic, flagellated protozoan parasite and the causative agent of trichomoniasis. It is the most common pathogenic protozoan infection of humans in industrialized countries. Infection rates between men and women are similar with women usually being symptomatic, while infections in men are usually asymptomatic. Transmission usually occurs via direct, skin-to-skin contact with an infected individual, most often through vaginal intercourse. The WHO has estimated that 160 million cases of infection are acquired annually worldwide. The estimates for North America alone are between 5 and 8 million new infections each year, with an estimated rate of asymptomatic cases as high as 50%. Usually treatment consists of metronidazole and tinidazole. Alfred Francois Donné (1801–1878) was the first to describe a procedure to diagnose trichomoniasis through 'the microscopic observation of motile protozoa in vaginal or cervical secretions' in 1836. He published this in the article entitled, 'Animalcules observés dans les matières purulentes et le produit des sécrétions des organes génitaux de l'homme et de la femme' in the journal, Comptes rendus de l'Académie des sciences. As a result, the official binomial name of the parasite is Trichomonas vaginalis DONNÉ. Trichomonas vaginalis, a parasitic protozoan, is the etiologic agent of trichomoniasis, and is a sexually transmitted infection. More than 160 million people worldwide are annually infected by this protozoan. Trichomoniasis, a sexually transmitted infection of the urogenital tract, is a common cause of vaginitis in women, while men with this infection can display symptoms of urethritis. 'Frothy', greenish vaginal discharge with a 'musty' malodorous smell is characteristic. Only 2% of women with the infection will have a 'strawberry' cervix (colpitis macularis, an erythematous cervix with pinpoint areas of exudation) or vagina on examination. This is due to capillary dilation as a result of the inflammatory response. Some of the complications of T. vaginalis in women include: preterm delivery, low birth weight, and increased mortality as well as predisposing to HIV infection, AIDS, and cervical cancer. T. vaginalis has also been reported in the urinary tract, fallopian tubes, and pelvis and can cause pneumonia, bronchitis, and oral lesions. Condoms are effective at reducing, but not wholly preventing, transmission. Trichomonas vaginalis infection in males has been found to cause asymptomatic urethritis and prostatitis. It has been proposed that it may increase the risk of prostate cancer; however, evidence is insufficient to support this association as of 2014. Classically, with a cervical smear, infected women have a transparent 'halo' around their superficial cell nucleus. It is unreliably detected by studying a genital discharge or with a cervical smear because of their low sensitivity. T. vaginalis was traditionally diagnosed via a wet mount, in which 'corkscrew' motility was observed. Currently, the most common method of diagnosis is via overnight culture, with a sensitivity range of 75–95%. Newer methods, such as rapid antigen testing and transcription-mediated amplification, have even greater sensitivity, but are not in widespread use. The presence of T. vaginalis can also be diagnosed by PCR, using primers specific for GENBANK/L23861.