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Epidemiology of HIV

I.    Overview of the American epidemic

A. Magnitude and trends in AIDS morbidity and mortality

1. Reported cases and deaths through December,

a. Adults: 633,000 cases and

b. Children: 8,086 cases and 4,724 deaths

2. Trends in cases attributed to changing risk behaviors

a. Race/ethnicity: Increases in blacks and

b. Gender: Increases in women, now 22% of adult cases

c. Geographic area: Increases in South and Midwest, smaller cities and

d. Transmission category: Increases in injecting drugs users, heterosexual transmission

3. Trends in cases and deaths attributed to improved prophylaxis and treatment

a. Adults

1) Comparing Jan-Sept 2006 with Jan-Sept 2006, cases have decreased by 14% and deaths by 44%, but least decline in female, black, and heterosexual contact cases

2) New York City data through early 2006 shows continuing

b. Children (1992-2006)

1) Perinatally acquired AIDS cases have declined by

B. Trends in opportunistic illnesses and use of preventive therapies (ASD Study, 1991-2006)

1. Opportunistic infections

a. Compared with IDUs, gay men show more consistent decrease in annual incidence of most common serious infections

b. Gay men make more outpatient visits, more likely to r

2. Malignancies

a. During era of combination antiretroviral therapy, clear decrease in incidence of Kaposi's sarcoma, possible decrease in primary brain lymphoma

b. To date, no clear decrease in incidence of other non-Hodgkin's lymphomas

C. Prevalence and incidence of HIV infection

1. HIV infection reporting (1994-2006)

a. HIV infection in adults reported by name in 25 states

b. Of persons reported with either HIV infection or AIDS, 72% were reported on the basis of HIV infection alone

c. Compared with persons reported with AIDS, those with HIV infection are younger, more likely to be female, non-white, and infected through heterosexual contact

2. Clinic-based seroprevalence surveys (2006)

a. Gay men attending STD clinics: Seroprevalence ranged from 3.7% (Minneapolis) to 31% (Houston)

b. IDUs entering drug treatment: Seroprevalence highest along East Coast ( Baltimore, 32%)and South (Atlanta, 25%) and lowest in West (LA, 1.5%)

3. Clinic-based seroincidence studies

a. Repeat attendees at STD clinics (1991-2006)

1) Annual incidence ranges from 0.8% to 7.0% among gay men and from 0.02% to 1.2% among heterosexual men and women

2) Incidence highest in young gay men and older heterosexuals

b. Repeat attendees at drug treatment centers (1990-2006)

1) Annual incidence ranges from 0% (Los Angeles) to 1.0% (New York City)

2) Since clinic attendees are likely at relatively low risk, true incidence in IDUs is probably higher

II. New laboratory methods as prevention tools

A. Use of rapid HIV antibody tests to increase detection of infected persons

1. Principle of rapid tests

a. New technologies provide preliminary serologic results within a few minutes

b. Sensitivity and specificity comparable to EIA

c. Negative results can be reported immediately

d. Positive results require confirmation

2. Study of licensed rapid test (SUDS) at Dallas anonymous test clinic and STD clinic

a. Rapid test increased proportion of clients receiving both positive and negative results

b. In STD clinic, reduced need for field visits to notify clients of

3. Potential applications of rapid tests

a. Publicly funded test sites

b. Acute health-care settings

c. Jails

d. High-risk women who present in labor without prior testing

e. Source patients of occupational exposures to blood

f. Cadaveric organ donors

B. Use of sensitive/less sensitive HIV antibody testing strategy to estimate incidence

1. Modification of testing conditions can reduce sensitivity of H IV antibody tests

2. Modification selected for study increased interval between infection and antibody detection by