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HIV Epidemiology


HIV Epidemiology

Contact Information
Los Angeles County
Department of Public Health
HIV Epidemiology, DHSP                       600 S. Commonwealth Ave. Suite 1920
Los Angeles, CA 90005
Phone: (213) 351-8196
Fax: (213) 487-9386


        LAC's ZIP code level data/maps on HIV

HIV Epidemiology - The Context of HIV Infection Project or "CHIP"

Past studies have documented that the distribution of HIV infection among risk and demographic groups in the United States has shifted over time.1,2,3 The epidemic, once primarily affecting White men who have sex with men, is now a growing concern for communities of color. In 1989, African Americans and Latinos represented 40% of all AIDS cases reported in Los Angeles County. In 2000, this proportion had increased to over 60%. Since old approaches to HIV prevention are unlikely to be effective among these and other emerging risk groups in Los Angeles, there is an urgent need to study the psychological, behavioral and environmental factors associated with recent HIV infections to guide the development of salient HIV prevention programs that target the populations at the leading edge of the epidemic.

Previous research has had limited success in identifying the factors associated with recent HIV infection, because methods to identify large numbers of recently infected persons have been unavailable. Fortunately, a major advancement in laboratory testing, the Serologic Testing Algorithm for Recent HIV Seroconversion (STARHS), makes it easier to differentiate persons with recent HIV seroconversion from those who became infected more than 12 months prior to testing.4 STARHS technology has already been used successfully to estimate HIV incidence rates in clinic-based study populations using stored serum specimens.3,5,6 In the "Context of HIV Infection Project" (CHIP), STARHS technology will be used to identify persons with evidence of recent HIV infection and compare them to a group of HIV seronegatives in order to identify the contextual factors associated with recent HIV seroconversion, as well as missed opportunities to prevent more recent HIV transmission.


There are two main objectives for the study:

1) To identify and understand factors associated with recent HIV infection, and 2) To identify missed HIV prevention opportunities that could have averted recent HIV infection. For each objective, we have specific research questions:

1. To identify and understand contextual factors associated with recent HIV infection.

  1. What individual and sexual partner sociodemographic characteristics are associated with recent seroconversion?
  2. What sexual practices are associated with recent seroconversion?
  3. What drug-use practices are associated with recent seroconversion?
  4. How do individual level behaviors, beliefs, knowledge and attitudes contribute to recent HIV infection (e.g., beliefs about HAART)?
  5. Which social and/or personal contextual factors (e.g., violence, discrimination, mental health), and the ways in which individuals cope with them, are associated with recent seroconversion?
  6. Do some social networks create an environment that promotes risky behaviors among certain individuals or groups?
2. To identify missed HIV prevention opportunities that could have averted recent HIV infection.
  1. What aspects of past HIV counseling and testing experiences have affected past and present HIV risk taking and HIV protective behaviors? What areas of recent high-risk behavior were not addressed in participantsí counseling?
  2. What prevention messages have had the most impact for changing HIV risk taking behavior and HIV protective behavior?
  3. What venues do people use for having high risk sexual or drug using behavior that can be targeted for HIV prevention outreach? Are there other venues that serve as meeting places for people who engage in risk behavior elsewhere, which can be targeted for outreach?
  4. What unmet prevention counseling needs exist for people at risk for HIV infection or people recently HIV infected?

Study Design:

CHIP is a multi-site study being conducted in Los Angeles, Chicago and Dallas. CHIP is closely related to a separate study, "Finding, Characterizing, and Referring Persons With Recent and Newly Diagnosed HIV Infections in Metro and South Service Planning Areas of Los Angeles County (Project One)." CHIP uses a matched case-control study design7 with both qualitative and quantitative data collection and analyses. Cases will be recruited from persons enrolled in Project One with recent HIV infection confirmed primarily through STARHS testing. Each case will be matched to three confirmed HIV-negative controls selected from the same HIV behavioral risk group (i.e., men who have sex with men [MSM], injecting drug users [IDU] and high risk heterosexuals [HRH]) who have obtained HIV testing services at the same testing sites from which the cases originated.

Contact Persons:

Ekow Kwa Sey, Project Epidemiologist, 213-351-8199

Trista Bingham, Principal Investigator, 213-351-8175.

  1. Rosenberg PS, Engels EA (1998). "Trends in HIV Incidence Among Youth." American Journal of Nursing 98(11): 25.
  2. Karon JM, Fleming PL, Steketee RW, DeCock KM (2001). "HIV in the United States at the Turn of the Century: An Epidemic in Transition." American Journal of Public Health 91(7): 1060-1068.
  3. Schwarcz S, Kellog TA, McFarland W, Louie B, Kohn R, Busch M, Katz M, Bolan G, Klausner J, Weinstock H (2001). "Differences in the Temporal Trends of HIV Seroincidence and Seroprevalence Among Sexually Transmitted Disease Clinic Patients 1989-1998 Application of the Serologic Testing Algorithm for Recent HIV Seroconversion." American Journal of Epidemiology 153(10): 925-934.
  4. Janssen RS, Satten GA, Stramer SL, Rawal B, O'Brien TR, Weiblen B, Hecht FM, Noreen J, Cleghorn FR, Kahn J, Chesney M, Busch MP. (1998). "New Testing Strategy to Detect Early HIV-1Infection for Use in Incidence Estimates and for Clinical and Prevention Purposes." JAMA 280(1): 42-48.
  5. McFarland W, Busch MP, Kellogg TA, Rawal BD, Satten GA, Katz MH, Dilley J, Janssen RS (1999). "Detection of Early HIV Infection and Estimation of Incidence Using a Sensitive/ Less Sensitive Enzyme Immunoassay Testing Strategy at Anonymous Counseling and Testing Sites in San Francisco." Journal of Acquired Immune Deficiency Syndrome 22(5): 484-490.
  6. McFarland W, Kellogg TA, Louie B, Murrill C, Katz MH (2000). "Low Estimates of HIV Seroconversions Among Clients of a Drug Treatment Clinic in San Francisco, 1995 to 1998." Journal of Acquired Immune Deficiency Syndrome 23(5): 426-429.
  7. Schlesselman JJ (1982). Case-Control Studies: Design, Conduct, Analysis. New York: Oxford University Press
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