Trichomoniasis, a Sexually Transmitted Infection caused by a parasite, infects more people in the U.S. each year than chlamydia, gonorrhea, and syphilis combined. And yet, according to a new survey, few people have even heard of it.

Trichomona Vaginalis trophozoite.

Prep4md / flickr

Most sexually transmitted infections (STIs) have a reputation or an identity among the general public; HIV is known because it causes AIDS and can be deadly, Herpes is the one that causes cold sores that you can see on the mouth and ones you can’t on the genitals, HPV is the one that has the vaccine and the reason women need pap smears, Syphilis can make you blind or crazy, chlamydia causes infertility, and gonorrhea is the one with the funny nickname (and the antibiotic resistance). But do they know the most common curable disease of them all?

According to a new survey from the American Sexual Health Association (ASHA), they do not. You see the most common curable STI of them all is trichomoniasis (called trich—for ease of pronunciation I assume) which is estimated to infect 7 to 8 million people in the United States each year. This means that trich infects more people than syphilis, chlamydia, and gonorrhea combined.

ASHA surveyed a representative sample of 1,000 women ages 18 to 50 to determine what they knew about trich and other STIs and how they felt about testing. The survey found:

Only 22 percent of respondents said they were familiar with trich compared to 79 percent who were familiar with HIV, 68 percent who were familiar with Herpes, 64 percent who were familiar with HPV, 56 who were familiar with chlamydia, 53 percent who were familiar with gonorrhea, and 52 who were familiar with syphilis.

Respondents also inaccurately ranked trich as the least common STD in the United States. In reality, it is one of the most. Trich, like Herpes and HPV, is not reportable to the CDC so the number of cases each year are estimated instead of counted. There are an estimated 7.4 million case of trich each year. The only STI that is estimated to infect more people is HPV with 14 million cases each year. In contrast, among the reportable STIs there were 1.4 million cases of Chlamydia, 321,849 cases of Gonorrhea, and13,970 cases of primary and secondary syphilis.

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Trich is caused by a parasite that is passed during sex. One reason so few people are aware of it may be that only about 30 percent of people infected with it have any symptoms. Men infected with trich rarely have symptoms. Women who do experience symptoms may have itching, burning, redness, or soreness in their genitals; discomfort when they urinate; a thin discharge that can be clear, white, yellowish, or greenish and has an unusual smell; and pain or discomfort during sex. These symptoms, however, mimic those of other STIs as well as simple vaginal infections such as yeast infection, and ASHA’s survey found that only 35 percent of women would seek testing if they had these symptoms. Most would wait for them to clear up or use over-the-counter treatments instead.

If left untreated, trich can be dangerous in part because the vaginal irritation it can cause leaves women more vulnerable to becoming infected with HIV. Moreover, it can be very dangerous to pregnant women; pregnant women infected with trich are more likely to give birth early and have low birth-weight (less than 5.5 pounds) babies.

The good news is that trich can be easily diagnosed using a swab of cervical and vaginal fluid or a urine test. New tests can even look for trich, chlamydia, and gonorrhea using the same sample. Once diagnosed, trich is easy to cure with a single round of antibiotics. The most important thing is that women have to ask to be tested.

The even better news: trich can be prevented by using latex condoms consistently and correctly.

Lynn Barclay, the president and CEO of ASHA referred to trich as the “forgotten STI.” For those who, like the majority of women, didn’t know about trich until today, here’s what Barclay calls the bottom line: “Testing for trich is simple, easy, and painless. Trich can be easily cured. If you have symptoms, seek medical attention and get tested for trich.” Pretty simple.