What is the Difference?

Although the terms “sexually transmitted disease (STD)” and “sexually transmitted infection (STI)” are often used interchangeably, they are by no means identical. STI is by far the more inclusive term. Sexually transmitted infection (STI) is an important and scientifically valid term because dangerous pathogenic organisms can be present in the human body without causing disease. It is therefore appropriate to refer to this condition as a sexually transmitted infection.

Sexually transmitted diseases (STDs) result from damage caused by a sexually transmitted infection (STI) that has progressed. Although all STDs are preceded by STIs, not all STIs result in the development of STDs. For instance, about 90% of women who are infected with human papillomavirus clear their infections within two years.[1] Only women with persistent infections are at risk for developing the disease – cervical cancer.[2] It is important to remember that it is not necessary to have a disease, or any symptoms at all, in order to be contagious. Many people who are infected with STIs that have not yet progressed to STDs have gone on to infect other people.

Another reason to learn about the difference between the two terms is that many STDs can be prevented through early screening and treatment of STIs. Since many infections that are highly contagious may be asymptomatic, STI screening should be based on risk behaviors (eg, early debut, multiple partners, anal intercourse) rather than symptoms alone. In this way, infections can be diagnosed and treated before they cause damage and develop into diseases or are spread to others.

At the PCC, we offer free and confidential STD testing for chlamydia and gonorrhea. (The PCC does NOT test for other STI/STD infections.) The test is done with a urine sample, and you will be scheduled for an appointment with our nurse to review your results. Results are typically available after one week. For clients who do test positive for one or both of these two STDs, we provide free treatment. Again, all services are free and confidential.



1. Ho GY, Bierman R, Beardsley L, Chang CJ, Burk RD. National history of cervicovaginal papillomavirus in young women. N Engl J Med. 1998;338(7):423-428. Available at: September 29, 2005.

2. Centers for Disease Control and Prevention. Genital HPV Infection Fact Sheet. Atlanta, GA: Centers for Disease Control and Prevention, US Dept of Health and Human Services; May 2004. Available at Accessed September 26, 2005. Authored by: Kate Hendricks, MD, MPH&TM

Reviewed by: Anjum Khurshid, MBBS, MPAff

Date: October 2004

Thanks to Medical Institute for Sexual Health for their excellent information.

*The Pregnancy Care Clinic does not provide abortion services or referrals, but we do provide accurate information on abortion that we hope we can share with you to help you make an informed decision.

*This information is intended for general educational purposes only and should not be relied upon as a substitute for professional medical advice.

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