These STIs are parasites that are passed from person-to-person during sexual activity.

These are the three most common: Trichomoniasis, Pubic Lice and Scabies


Trichomoniasis, or trich (pronounced “trick”), is a common STI caused by single celled protozoan parasite called Trichomonas vaginalis. Women are more vulnerable than men and it is the most common non-viral STI in the world, with an estimated 248 million new cases per year. Trichomoniasis is spread through sexual or genital contact with an infected person. Most patients (70%), especially men, do not show symptoms of a trich infection. Some general symptoms for women may include: discharge from the vagina, vaginal odour, painful urination and irritation or itchiness of the vagina. For men symptoms may include: mild discharge, irritation or redness at the top of the penis, burning during urination.

Pubic Lice

‘Crabs’ or ‘pubic lice’ are tiny lice (like head lice) that live in pubic hair, around the genitals. They measure in at about a millimetre tall, bury their heads into the skin, and live off human blood. They lay their egg sacks (nits) near the base of the pubic hair. A substance they secrete into the skin can cause intense itching, and the bites of adult lice turn small patches of skin to a bluish-grey colour. Fine black particles maybe spotted in the infected person’s underwear. Unlike head lice, pubic lice have small, wide bodies and arms that resemble crabs (hence the nickname). These lice can also be found in chest, armpit and facial hair, eyebrows and eyelashes. ‘Crabs’ or ‘pubic lice’ affect 2% of the world population. Pubic lice can spread during intimate skin-to-skin contact and through sexual intercourse. They can also be transmitted by sharing bedding, towels and clothing belonging to person who has pubic lice.


Scabies are parasitic mites that dig holes (burrow) under the surface of the skin and lay eggs. The larvae that hatch move to new areas of the body and spread the infection. Mites prefer warm areas such as the folds of skin on the elbows, wrists, buttocks, knees, shoulder blades, waist, breasts, and penis, between the fingers, and under the nails.