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Chlamydia Profiles, 2008

This web page is archived for historical purposes and is no longer being updated. Newer data is available on the STD Data and Statistics page.

STD Surveillance 2008

Regional | State | City | Data Sources | Data Limitations

Regional Profiles

Regional Profiles

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Figure A Data, All Regions - Chlamydia - Trends in positivity in 15 to 24 year old women tested in family planning clinics

Each of the Regional Profiles, one for each of the ten HHS regions, contains a map of the region and a bar graph showing trends in chlamydia positivity rates among women 15 to 24 years of age attending family planning clinics. Information on the proportion of all chlamydia tests performed that were nucleic acid amplification tests (NAATs) is included. NAATs are the most sensitive tests currently available for the detection of genital Chlamydia trachomatis infections and may be performed on a variety of biologic specimens. NAAT usage has been increasing over time in each of the ten HHS regions. For more information on NAAT usage in this population, see Figure 12 of STD Surveillance, 2008. For more information on prevalence monitoring data, see below.

State Profiles

State Profiles

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Figure A Data, All States - Chlamydia rate per 100,000 women, 1999 - 2008
Figure B Data, All States - Chlamydia positivity in women 15 to 24 years of age, by testing site, 1999 - 2008
Figure C Data, All States - Chlamydia positivity by age group in women attending family planning clinics, 2008
Table 1 Data, All States - Chlamydia positivity in women 15 to 24 years of age, by testing site, 2008

Each of the State Profiles on chlamydia positivity trends contains three figures and one table.

Morbidity Surveillance: Reporting of Chlamydia Cases

Crude incidence rates (new cases/population) were calculated on an annual basis per 100,000 population. Rates for all states were calculated by dividing the number of cases reported from each state by the estimated state-specific population (the most current detailed population file available at time of publication). The National Center for Health Statistics releases annual bridged race population counts based on the Census 2000 counts. These estimates result from bridging the 31 race categories used in Census 2000, as specified in the 1997 Office of Management and Budget (OMB) standards, to the five race/ethnicity groups specified under the 1977 OMB standards.

From 2001 to 2002, population estimates for Guam were obtained from the Guam Bureau of Statistics and Plans; estimates for Puerto Rico were obtained from the Bureau of Census; and estimates for the Virgin Islands were obtained from the University of the Virgin Islands. After 2002, population estimates for all outlying areas were obtained from the Bureau of Census website.

The population counts for 1999 incorporated the bridged single-race estimates of the April 1, 2000, resident population. These files were prepared by the U.S. Census Bureau with support from the National Cancer Institute.

Due to use of updated population data, rates presented in the current State Profiles may be different from prior State Profiles.

Prevalence Monitoring: Reporting of Chlamydia Positivity

Chlamydia test positivity was calculated by dividing the number of women testing positive for chlamydia (numerator) by the total number of women tested for chlamydia (denominator includes those with valid test results only and excludes unsatisfactory and indeterminate tests) and is expressed as a percentage. The denominator may contain multiple tests from the same individual if that person was tested more than once during the period for which screening data are reported. The numerator may also contain multiple positive test results from the same individual if that person tested positive more than once during the period for which screening data are reported. Various chlamydia laboratory methods were used and no adjustments of test positivity were made based on laboratory test type and sensitivity. Chlamydia prevalence data on female National Job Training Program entrants are not presented when the number of persons tested from a state was fewer than 100 in the past year. The number of clinics cited in Table 1 for each state represents family planning (FP), sexually transmitted disease (STD), prenatal, and other clinics screening 25 or more women and juvenile and adult corrections facilities screening 100 or more women. To be included in Figure B, FP and STD clinics must have each had data on at least 50 tests in any given year. Each age group displayed in Figure C represents data on at least 100 tests within the past year.

City Profiles

City Profiles have been discontinued. Local areas are encouraged to create their own profiles to best reflect their geographic area and available data. Data on chlamydia cases and rates at the MSA are in the current STD surveillance report.

Data Sources

Regional Infertility Prevention Projects

Chlamydia screening and prevalence monitoring activities were initiated in Health and Human Services (HHS) Region X in 1988 as a CDC-supported demonstration project. In 1993, as part of the development of the National Infertility Prevention Program (IPP), chlamydia screening services for women were initiated in three additional HHS regions (III, VII, VIII); in 1995, services were implemented in the remaining HHS regions (I, II, IV, V, VI, IX). All regional projects, in collaboration with state STD control and family planning programs, have reported chlamydia positivity data to CDC since 1997. In some of the HHS regions, federally-funded chlamydia screening supplements existing local- and state-funded testing programs. These publicly-funded programs support chlamydia screening primarily in family planning clinics, but also in some STD clinics, prenatal clinics, jails and juvenile detention centers, and other sites.

The 10 HHS regions referred to in the text and figures are as follows:

  • Region I: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont
  • Region II: New Jersey, New York, Puerto Rico, and U.S. Virgin Islands
  • Region III: Delaware, District of Columbia, Maryland, Pennsylvania, Virginia, West Virginia
  • Region IV: Alabama, Florida, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee
  • Region V: Illinois, Indiana, Michigan, Minnesota, Ohio, Wisconsin
  • Region VI: Arkansas, Louisiana, New Mexico, Oklahoma, Texas
  • Region VII: Iowa, Kansas, Missouri, Nebraska
  • Region VIII: Colorado, Montana, North Dakota, South Dakota, Utah, Wyoming
  • Region IX: Arizona, California, Hawaii, Nevada
  • Region X: Alaska, Idaho, Oregon, Washington

See for a map.

State and Local Health Departments

As of 2000, all 50 states and the District of Columbia had regulations requiring the reporting of chlamydia cases.

Corrections Facilities

Corrections data are reported as part of the Regional Infertility Prevention Projects or in response to CDC’s request for data.

Indian Health Service

The Indian Health Service National STD Program provides support for chlamydia screening and treatment services for at-risk Alaska Native/American Indian women through the Stop Chlamydia Project. Data are from tests conducted among women who attended IHS, Tribal, and Urban Indian health centers.

National Job Training Program

Since 1990, approximately 20,000 female National Job Training Program entrants have been screened each year for chlamydia, with all tests performed at a central contract laboratory. Changes in the test type used for females occurred in 1998, switching from the EIA to the DNA hybridization probe (GenProbe PACE 2). Beginning in 2000, a small proportion of females were screened using the strand displacement assay (BDProbeTec ET). By 2006, most females were screened using the strand displacement assay. Since July 2003, male National Job Training Program entrants have also been screened for chlamydia using the strand displacement assay. Annually, over 35,000 men are screened. The National Job Training Program is primarily a residential job training program for urban and rural economically-disadvantaged youth 16 to 24 years of age at more than 100 sites throughout the country. The chlamydia test results from the National Job Training Program were used to calculate prevalence in this population.

Data Limitations

The interpretation of chlamydia data is complicated by several factors. First, case reports and prevalence data result from the use of several different types of diagnostic tests for chlamydial infection (e.g., direct fluorescent antibody, EIA, DNA probe assay, nucleic acid amplification); these tests vary in their sensitivity and specificity. Nucleic acid amplification tests (NAATs) are the most sensitive tests currently available in the United States. Second, chlamydia positivity in women attending clinics is an estimate of prevalence; it is not true prevalence. Crude positivity may include those women who are tested two or more times during a single year. Comparisons of positivity with prevalence have shown that in family planning clinics, positivity is generally similar to or slightly higher than prevalence, and in STD clinics, positivity is somewhat lower than prevalence; however, these differences are usually small, with a relative difference of less than 10% (Dicker et al., 1998). Third, while nearly all family planning clinics perform universal screening of sexually active women < 20 years of age, and most clinics do so among women < 26 years of age, some selective screening is performed among women 20- to 25-years of age and selective screening is frequently performed among women > 26 years of age. Fourth, family planning and other clinic-based data reported to CDC may not be fully representative of the entire clinic population. Reporting completeness requirements and programmatic influences may lead to only partial reporting from some clinics. Finally, while monitoring prevalence among persons seeking care at clinics provides important information on certain segments of the population, these data cannot be generalized to the population as a whole.

In the National Job Training Program, data are limited to entrance exam testing; therefore, no one is included twice and true prevalence is ascertained. All persons entering the National Job Training Program are required to be tested.

As noted above, various laboratory test methods were used for all data. The figures presented in this report do not include an adjustment of test positivity based on laboratory test type and sensitivity.

All 2008 Chlamydia Regional and State Profiles

All Years Chlamydia Profiles and Prevalence Monitoring Project Annual Reports

More information about Chlamydia