Of course its an STD! It is a parasite that eats away the benificial bacteria in the vaginal tract and produces foul odor.

See this link to educate yourself:


http://www.smartersex.org/stis/trichomoniasis.asp


Here is some of what you'll find on this website link:

Trichomoniasis, an infection that affects both men and women, is caused by a microscopic parasite. Bacterial vaginosis (BV), which is not a "classic" STI, is caused by an imbalance in the bacteria normally found in the vagina, and only affects women. Although these diseases haven't been studied to the extent of some other STIs, they are among the most common conditions found in women. While these diseases are treatable, BV is associated with pelvic inflammatory disease, and both trichomoniasis and BV may increase the risk of HIV infection.

Prevalence: An estimated five million cases of trichomoniasis occur each year in the United States. Studies show that bacterial vaginosis is common in women of reproductive age and as many as 16 percent of pregnant women in the United States are infected with BV.

Symptoms
Trichomoniasis: Most men with trichomoniasis do not experience any symptoms, but those who do experience an irritation inside the penis, mild discharge, or slight burning after urination or ejaculation. In women, trichomoniasis causes a frothy, yellow-green vaginal discharge with a strong odor. The infection may also cause discomfort during intercourse and urination. Irritation and itching of the female genital area and, in rare cases, lower abdominal pain can also occur.

Bacterial Vaginosis: Women with BV often have an abnormal vaginal discharge with an unpleasant odor. Some women report a strong fish-like odor, especially after intercourse or when washing the vulva with soap. The discharge is usually white or gray and can be thin. Women with BV may also have burning during urination or itching around the outside of the vagina, or both. Some women with BV report no signs or symptoms at all.

I don't know if they can be tested per se but I will tell you it most definitely can be passed to your s.o. I battled bv for almost 10 years, finally I got a doctor that prescibed meds for my hubby too, we did the treatment at the same time and abstained from sex all together throughout treatment. It has now been 3 years and I have NOT had a single recurrence!