"Reported" STI cases are those for which the results of a medical test have been reported at the local, state, or federal level. While STI reporting requirements and mechanisms have improved, they do have limitations. Even the best national STI reporting system falls far short of determining the actual number of STI cases. Here are some reasons:
- many STIs cause no symptoms at all or result in "delayed" symptoms
- for a variety of reasons, even when they have symptoms of an STI, some people still don't seek medical care (e.g., they may not know where to go; they may not have the financial resources to pay for treatment; they may deny that they have symptoms)
- Doctors often treat patients for STIs without performing a laboratory test that would help them make a specific diagnosis
- Doctors and laboratories may fail to report patients with laboratory-confirmed STIs

Public Health officials are highly aware of the limitations of the reporting system, and consider all of these factors when they "estimate" the number of STI cases.

For example, although just over 1 million cases of chlamydia were reported in 2006, the estimated number of new chlamydia infections is more than 2 million.¹

Reviewed by: Jennifer A. Shuford, MD, MPH
Date: October 2008

Reference:
1. Centers Centers for Disease Control and Prevention. Chlamydia - CDC fact sheet [fact sheet on the Internet; Content reviewed: 2007 Dec 20]. Atlanta, GA: Centers for Disease Control and Prevention. Available from: http://www.cdc.gov/std/Chlamydia/STDFact-Chlamydia.htm. Accessed 2008 Mar 28. (Archived by WebCite® at http://www.webcitation.org/5YM07t79S; cached 2008 Jun 5).