|Description:||This photomicrograph of a wet-mounted vaginal discharge specimen, reveals numbers of Trichomonas vaginalis protozoan parasites, leading to a diagnosis of trichomoniasis, or “trich”, which is a very common sexually transmitted disease (STD) that is caused by infection with T. vaginalis. Although symptoms of the disease vary, most women and men who have the parasite cannot tell they are infected.|
The parasite is passed from an infected person to an uninfected person during sex. In women, the most commonly infected part of the body is the lower genital tract (vulva, vagina, or urethra), and in men, the most commonly infected body part is the inside of the penis (urethra). During sex, the parasite is usually transmitted from a penis to a vagina, or from a vagina to a penis, but it can also be passed from a vagina to another vagina. It is not common for the parasite to infect other body parts, like the hands, mouth, or anus. It is unclear why some people with the infection get symptoms while others do not, but it probably depends on factors like the person’s age and overall health. Infected people without symptoms can still pass the infection on to others.