Surveillance of HIV Infection

This report includes data from case reports from 39 areas that had laws or regulations requiring confidential name-based HIV infection reporting for adults, adolescents and children since at least 2003, in addition to the reporting of persons with AIDS. Data in this report are from cases reported according to the 2000 revised HIV surveillance case definition [1].

Surveillance of AIDS

AIDS cases are reported to CDC by all 50 states, the District of Columbia, and U.S. dependent areas, by use of a uniform surveillance case definition and case report form. Data in this report are from cases reported according to the 2000 revised HIV surveillance case definition [1]. Persons in whom HIV infection progressed to AIDS are reported as having AIDS.

Tabulation of Data

The supplemental report is organized in 2 sections: (1) cases of HIV/AIDS and AIDS and (2) persons living with HIV/AIDS or AIDS. Data estimating the number of persons with diagnoses of HIV/AIDS or AIDS and the number of persons living with HIV/AIDS or AIDS have been statistically adjusted to correct for delays in the reporting of cases and for missing risk-factor information. For the assessment of trends in diagnoses or prevalence, it is preferable to use adjusted data, presented by year of diagnosis instead of year of report, to eliminate artifacts of reporting in the surveillance system. The racial/ethnic distribution of cases of HIV/AIDS reflects the racial/ethnic distribution of the 39 areas and should not be considered representative of all persons with HIV/AIDS in the United States.

The data in this report are provisional. This report includes information received by CDC through June 30, 2008.

Inclusion of Areas with Mature HIV Reporting Systems for Analysis of Cases of HIV Infection

The inclusion of areas with mature confidential name-based HIV reporting for the tabulation and presentation of HIV/AIDS data was based on the date that HIV infection reporting was implemented in the area and the ability to calculate 4 years of reporting delays in order to display trends reliably. This report includes the 39 areas with laws or regulations requiring confidential name-based HIV infection reporting since 2003. The 39 areas comprise 34 states (Alabama, Alaska, Arizona, Arkansas, Colorado, Florida, Georgia, Idaho, Indiana, Iowa, Kansas, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Nebraska, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, West Virginia, Wisconsin, and Wyoming) and 5 U.S. dependent areas (American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the U.S. Virgin Islands). Georgia was added to the tables for estimated HIV/AIDS for the first time in this report and the most recent surveillance report [2], increasing the number of states included in these analyses from 33 to 34.

Race and Ethnicity

In the Federal Register for October 30, 1997 [3], the Office of Management and Budget announced the Revisions to the Standards for the Classification of Federal Data on Race and Ethnicity. Implementation by January 1, 2003, was mandated. At a minimum, data on the following racial categories should be collected: American Indian or Alaska Native; Asian; black or African American; Native Hawaiian or other Pacific Islander; and white. Additionally, systems must be able to retain information when multiple racial categories are reported. In addition to data on race, data on 2 categories of ethnicity should be collected: Hispanic or Latino and not Hispanic or Latino. Hispanics/Latinos can be of any race.

The new racial categories were used for the first time for HIV/AIDS and AIDS surveillance data in the previous version of this supplemental report [4] and the most recent annual surveillance report (the 2007 HIV/AIDS Surveillance Report) [2]. The numbers displayed for the Asian/Pacific Islander category in earlier annual and supplemental reports are not comparable to the numbers displayed for the 2 new racial categories: (1) Asian and (2) Native Hawaiian and other Pacific Islander. The Asian category includes the cases in Asians/Pacific Islanders (referred to as legacy cases) that were reported before the implementation of the new racial categories in 2003 and a small proportion of cases in Asians and Native Hawaiians/Other Pacific Islanders that were reported after 2003 but that were reported according to the old racial category (Asian/Pacific Islander).

Age

The designation “adults and adolescents” refers to persons aged 13 years and older, the designation “children” refers to persons less than 13 years of age. For presentation of data on persons living with HIV infection or with AIDS, the age designation is based on the person’s age as of December 31, 2007.

For all other tables, the age designation (for example, “adults and adolescents”) or the specific age group (for example, 20–24 years) is based on the person’s age at the time of the first documented positive result of an HIV antibody test (for persons with a diagnosis of HIV infection) or the person’s age at the time AIDS was diagnosed.

Geographic Designations

The areas of residence included in the report are defined as follows.

Northeast: Connecticut, Maine, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Vermont

Midwest: Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin

South: Alabama, Arkansas, Delaware, District of Columbia, Florida, Georgia, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, and West Virginia

West: Alaska, Arizona, California, Colorado, Hawaii, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming

U.S. dependent areas: American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, and the U.S. Virgin Islands

Persons Living with HIV Infection or AIDS

Tabulations of persons living with HIV/AIDS or with AIDS do not reflect actual counts of cases reported to the surveillance system. Rather, the estimates are based on numbers of reported cases, which have been adjusted for delays in the reporting of cases and deaths.

Transmission Categories

For surveillance purposes, cases of HIV/AIDS and AIDS are counted only once in a hierarchy of transmission categories. Persons with more than one reported risk factor for HIV infection are classified in the transmission category listed first in the hierarchy. The exception is men who report sexual contact with other men and injection drug use; this group makes up a separate transmission category.

Persons whose transmission category is classified as male-to-male sexual contact include men who report sexual contact with other men (i.e., homosexual contact) and men who report sexual contact with both men and women (i.e., bisexual contact). Persons whose transmission category is classified as high-risk heterosexual contact are persons who report specific heterosexual contact with a person known to have, or to be at high risk for, HIV infection (e.g., an injection drug user).

Adults and adolescents born in, or who had sex with someone born in, a country where heterosexual transmission was believed to be the predominant mode of HIV transmission (formerly classified as Pattern II countries by the World Health Organization) are no longer classified as having heterosexually acquired HIV infection unless they meet the criteria for high-risk heterosexual contact stated in the preceding paragraph. Similar to other cases among persons who were reported without information about a behavioral or transfusion risk factor for HIV infection, these cases are now classified (in the absence of other risk factor information that would classify them in another transmission category) as “no risk factor reported or identified” [5].

Cases in persons with no reported exposure to HIV through any of the routes listed in the hierarchy of transmission categories are classified as “no risk factor reported or identified.” No identified risk factor (NIR) cases include cases that are being followed up by local health department officials; cases in persons whose exposure history is missing because they died, declined to be interviewed, or were lost to follow-up; and cases in persons who were interviewed or for whom other follow-up information was available and no risk factor was identified.

Because a substantial proportion of cases of HIV infection and AIDS are reported to CDC without an identified risk factor, a statistical approach—multiple imputation—has been used in this report to assign a risk factor for these cases. Multiple imputation is a statistical approach in which each missing risk factor is replaced with a set of plausible values that represent the uncertainty about the true, but missing, value [6,7]. In this report, multiple imputation has been used in tables showing estimated values for cases in adults and adolescents, but not in tables concerning cases in children (because the number of cases in children is small, missing risk factors were not imputed for these cases).

Rates

Rates per 100,000 population were calculated for the numbers of cases of HIV/AIDS and AIDS in 2007, as well as for persons living with HIV/AIDS at the end of 2007. The population denominators used to compute these rates for the 50 states and the District of Columbia were based on official postcensus estimates for 2007 from the U.S. Census Bureau [8]. These rates differ slightly from those in the 2007 HIV/AIDS Surveillance Report; in that report, the rates were based on bridged-race estimates for 2007 obtained from the National Center for Health Statistics [9].

References

1. CDC. Guidelines for national human immunodeficiency virus case surveillance, including monitoring for human immunodeficiency virus infection and acquired immunodeficiency syndrome. MMWR 1999;48(RR-13):29–31.
2. CDC. HIV/AIDS Surveillance Report, 2007. Vol. 19. Atlanta: U.S. Department of Health and Human Services, CDC; 2009.
3. Office of Management and Budget. Revisions to the standards for the classification of federal data on race and ethnicity. Federal Register 1997;62:58781–58790. Accessed March 18, 2009.
4. CDC. Cases of HIV Infection and AIDS in the United States and Dependent Areas, by Race/Ethnicity, 2002–2006. HIV/AIDS Surveillance Supplemental Report 2008;13(No. 1).
5. CDC. Current trends: heterosexually acquired AIDS—United States, 1993. MMWR 1994; 43(9):155–160.
6. Rubin DB. Multiple Imputation for Nonresponse in Surveys. New York: John Wiley & Sons Inc; 1987.
7. McDavid Harrison K, Kajese T, Hall HI, Song R. Risk factor redistribution of the national HIV/AIDS surveillance data: an alternative approach. Public Health Rep 2008;123(5):618–627.
8. U.S. Census Bureau. Population estimates [entire data set]. Published May 1, 2008. Accessed March 17, 2009.
9. National Center for Health Statistics. Bridged-race vintage 2007 postcensal population estimates for July 1, 2000–July 1, 2007, by year, county, single-year of age, bridged-race, Hispanic origin, and sex. Accessed December 20, 2008.