Author: Marie Hartley, staff writer, 2009.
Trichomoniasis is an extremely common, sexually transmitted infection (STI) caused by the protozoan parasite, Trichomonas vaginalis. Around 3.1% of women of reproductive age in the United States are infected with T. vaginalis; with an estimated 180 million new infections acquired worldwide per year. Females can acquire the disease from infected males or females; but males usually acquire it only from infected females.
The incubation period is generally between 4 and 28 days. Trichomoniasis is a marker of high-risk sexual behaviour. Co-infection with other STIs is common, especially Chlamydia trachomatis and Neisseria gonorrhoeae (gonorrhoea).
Around half of infected females will have no symptoms from trichomoniasis. Females can be asymptomatic carriers for months or years.
Physical signs of trichomoniasis include:
T. vaginalis is present in 30-70% of the male partners of infected females. Most infected males (>90%) will have no symptoms. When symptoms are present they are usually a result of urethritis (inflammation of the urethra) and include irritation inside the penis, scant, thin discharge, or slight burning after urination or ejaculation. These symptoms usually disappear within a few weeks without treatment. However, an infected male (even those who have never had symptoms) can continue to infect or re-infect a female sexual partner until he has been treated.
Up to 11% of cases of non-gonococcal urethritis in males are caused by T. vaginalis.
The following methods can be used to detect T. vaginalis:
There is little immunity gained as a result of T. vaginalis infection, i.e. having had trichomoniasis once does not protect a person from getting it again. Safe sex practices, including limiting the number of sexual partners and using condoms, can reduce the transmission of T. vaginalis.
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