HIV Statistics

HIV/AIDS Statistics & Surveillance

Timely and accurate HIV and AIDS case reporting provides a better understanding of the epidemic on local levels. Epidemiologists can monitor trends in populations being affected by HIV infection; project future numbers of cases and provide information for those responsible for planning for future health care needs, prevention and educational activities.

Failure to report in a timely manner may have an impact on current and projected funding needs. Funding formulas using data that represents under-reporting of HIV or AIDS cases may translate into under-funded programs and services for those with HIV infection. Collecting information about HIV will help us to get a better understanding of HIV in our state. We need to know if people with HIV are getting the care they need. HIV information is also used to obtain funds for HIV prevention and treatment services.

  • 1981-Confidential name-based AIDS case reporting began in Pennsylvania

Understanding HIV/AIDS Surveillance

Surveillance Definitions

Please visit the Pennsylvania Department of Health, Bureau of Epidemiology website for general HIV/AIDS statistical summaries.

Please visit the Statistics Center for more information.

Stages of HIV Infection

The 2008 revised HIV case definition was used to classify HIV infection among adults and adolescents and among children [3]. The revised definition incorporates an HIV infection classification staging system that includes AIDS (HIV infection, stage 3). The stages of HIV infection are defined as follows:

  • HIV infection, stage 1: No AIDS-defining condition and either CD4 count of ≥500 cells per microleter (/μL) or CD4 percentage of total lymphocytes of ≥29.
  • HIV infection, stage 2: No AIDS-defining condition and either CD4 count of 200-499 cells/μL or CD4 percentage of total lymphocytes of 14 to 28.
  • HIV infection, stage 3 (AIDS): Documentation of an AIDS-defining condition or either a CD4 count of <200 cells/μL or a CD4 percentage of total lymphocytes of <14. Documentation of an AIDS-defining condition supersedes a CD4 count or percentage that would not, by itself, be the basis for a stage 3 (AIDS) classification.
  • HIV infection, stage unknown: No reported information on AIDS-defining conditions and no information available on CD4 count or percentage.

Although AIDS cases have been reported to CDC since 1981, the implementation of HIV infection reporting has differed from state to state. As of April 2008, all states, the District of Columbia, and 6 U.S. dependent areas had fully implemented name-based HIV infection reporting. Case report data is available from all 50 states, the District of Columbia, and 6 U.S. dependent areas (American Samoa, Guam, the Northern Mariana Islands, Puerto Rico, the Republic of Palau, and the U.S. Virgin Islands) in which laws or regulations require confidential reporting by name for adults, adolescents, and children with confirmed diagnoses of HIV infection. After the removal of personal identifying information, data from these reports are submitted to CDC.

Transmission Category

Transmission category is the term for the classification of cases that summarizes a person's possible HIV risk factors; the summary classification results from selecting, from the presumed hierarchical order of probability, the 1 risk factor most likely to have been responsible for transmission. For surveillance purposes, a diagnosis of HIV infection is counted only once in the hierarchy of transmission categories. Persons with more than 1 reported risk factor for HIV infection are classified in the transmission category listed first in the hierarchy. The exception is men who had sexual contact with other men and injected drugs; this group makes up a separate transmission category. Persons whose transmission category is classified as male-to-male sexual contact include men who have ever had sexual contact with other men (i.e., homosexual contact) and men who have ever had sexual contact with both men and women (i.e., bisexual contact).

Persons whose transmission category is classified as heterosexual contact are persons who have ever had heterosexual contact with a person known to have, or to be at high risk for, HIV infection (e.g., an injection drug user).

Additional Information

For more information about HIV/AIDS Surveillance, contact Sharita Flaherty.