One of those sexually transmitted diseases (STD) that is way less kind to women then men, trichomoniasis is caused by a parasitic one-celled protozoan that travels between people during sexual intercourse. For women, the symptoms include painful urination, genital itching and a foul-smelling vaginal discharge. Men typically are spared any symptoms. When they do get hit, it's with irritation inside the penis, discharge from the penis, and a burning sensation with urination or after ejaculation.

The incubation period between exposure and infection is not exactly known, but doctors' best guess is from five to 28 days.

Women (and the rare man) who experience the discharge or pain during intercourse/urination should see their doctor. She will confirm her diagnosis by examining the discharge under a microscope, utilizing tests known as nucleic acid amplification and rapid antigen tests.

Regardless of which sexual partner has symptoms, both will need to be treated, and both will need to avoid sexual intercourse until the infection is cured. The usual approach is a megadose of of either metronidazole or tinidazole.  (Trichomoniasis patients on the mend are usually cautioned not to drink alcohol for 24 hours after taking metronidazole or 72 hours after taking tinidazole, because it can cause severe nausea and vomiting.)

Pregnant women who contract trichomoniasis are a special case, as they may experience a number of complications. These include:

• A higher risk of delivering their babies prematurely
• Transmission of the infection to the baby as he or she passes through the birth canal
• Deliver a baby with a low birth weight
• Increased susceptibility them to become infected with HIV, the virus that causes AIDS.

As with all STDs, the only way to prevent trichomoniasis is to abstain from sex. To lower your risk, use condoms correctly every time you have sex.