the biases from increased screening practices or inconsistent application of case definitions, since the populations under surveillance and participating providers are well defined. Perhaps the best functioning sentinel STD surveillance system is the Gonococcal Isolate Surveillance Project sponsored by the CDC. This project collects data from 21 nationwide sites to assess patterns in gonorrhea isolate antimicrobial resistance.
Coordinated by the National Center for Health Statistics, the National Health and Nutrition Examination Survey (NHANES) collects health-related data from a randomly selected sample of the U.S. population. In addition to data regarding self-reported health behaviors, blood samples collected at the time of interview provide critical information regarding the actual prevalence of diseases through detection of serological markers. This is particularly useful for some viral STDs that are often asymptomatic, including herpes simplex virus infection, hepatitis B virus infection, and HIV infection (McQuillan et al., 1989, 1994; Johnson et al., 1993). For example, using these data, public health officials have estimated that at least one of four European American women and one in five European American men will be infected with genital herpes in their lifetime (Johnson et al., 1993).
Provider-based information systems are used to estimate the scope and frequency of treatment among private sector and other physicians and can provide useful data on STDs to supplement disease surveillance data. The National Disease and Therapeutic Index is a commercially developed provider database that systematically collects patient encounter data from a stratified sample of U.S. private practice physicians. It has been used to follow trends in the diagnosis of some nonreportable STDs, such as genital warts caused by human papillomavirus, genital herpes, vaginal infections, and nongonococcal urethritis. Another potential method for assessing STD trends is by monitoring of the sequelae of STDs. For example, the National Ambulatory Care Survey and the National Hospital Discharge Survey have been used to monitor rates of pelvic inflammatory disease. Physician consultations for infertility and cervical cancer rates within specific populations also may be used as surrogates for underlying STD trends. In addition, disease registries are helpful in documenting the occurrence of STDs in specific communities and in conducting clinical research. For example, a national disease registry collects information regarding infants exposed to herpes simplex at birth and treated with acyclovir. Although limited in scope, these registries provide useful information on treatment of STDs.
A crucial but underdeveloped tool for directing and targeting STD prevention programs is the behavioral health survey. Surveys that regularly collect nationally representative information on specific STD-related risk behaviors are important in monitoring national trends and have become more prominent since