Persons with acute HIV infection (AHI) may be responsible for a substantial proportion of onward transmission of HIV infection, especially in sub-Saharan Africa. AHI, the period between infection and seroconversion, lasts up to 10-12 weeks. During this brief window of time, the virus replicates rapidly, leading to high concentrations of HIV RNA in blood and genital secretions. Consequently, the probability of transmission during unprotected intercourse is very high. Identifying persons with AHI and intervening to reduce onward transmission represents a tantalizing, but unproven, opportunity for HIV prevention. We propose an aggressive HIV transmission prevention program to identify persons with AHI and intervene behaviorally and biologically. Our central hypothesis is that persons with acute HIV infection play an important role in HIV transmission. We further hypothesize that behavioral and treatment interventions in acutely infected persons will reduce onward transmission. To address these hypotheses, we will conduct an exploratory study complemented by mathematical modeling to assess the potential impact of the proposed prevention program. The specific aims of our proposed study are to: 1) Develop a novel program to prevent HIV transmission by identifying and informing persons with acute HIV infection (AHI) in Lilongwe, Malawi, 2) Evaluate a short-term, combined behavioral and antiretroviral therapy (ART) intervention to prevent HIV transmission among persons with AHI, 3) Determine the potential individual and combined impact of each component of the intervention using mathematical modeling. To achieve these aims, we will use our well-established infrastructure in Lilongwe, Malawi. We will take advantage of new and existing technologies to identify people with AHI more rapidly. Immediately after diagnosis, persons will be randomized to standard counseling, an intensive behavioral intervention, or the behavioral intervention combined with short term antiretroviral therapy (ART). The behavioral intervention is based on the Information-Motivation- Behavioral Skills Model. The ART will use new and potent antiretroviral drugs to rapidly block HIV replication and limit infectiousness. Using the data collected in this pilot study, we will use rigorous mathematical modeling to assess the potential impact of the prevention program on the epidemic within a community and plan a large randomized trial. Persons with acute HIV infection (AHI), the earliest stage of HIV infection, may transmit HIV infection at a high rate, especially in sub-Saharan Africa. Given this important possibility, we hypothesize that behavioral and treatment interventions in acutely infected persons will reduce their transmission. To address this hypothesis, we will conduct an exploratory study, coupled with mathematical modeling, to examine the potential impact of combining a behavioral intervention with a course of antiretroviral treatment in persons with AHI.