This is a prospective observational study of couples in Kisarawe, Tanzania who will be provided an intervention that offers: (1) HIV self-testing kits and pre-test counseling provided at the household, (2) linkage to a counseling and referral center for those who test positive, (3) facilitated enrollment to care and treatment for couples with confirmed HIV infection; and (4) access to pre-exposure prophylaxis for the negative partner in a HIV sero-discordant couple. We will identify HIV sero-discordant couples through the HIV self-testing component, and through identifying discordant couples at the local HIV clinic. HIV sero-discordant couples (N=64 couples) will be administered a baseline, 6- ,12-, and 18-month survey, and the investigators will collect ongoing clinical data from each clinic visit. Biometric data (fingerprint) will be collected at enrollment, and all encounters with the counseling and referral center, and HIV treatment center, to allow linking of utilization of services with survey data.

The investigators propose to conduct a prospective observational study of cohabitating couples aged 18 years and above in Kisarawe, Tanzania who will be provided: (1) distribution of HIV self-testing kits to cohabitating couples; (2) linkage to confirmatory HIV-testing & counseling for those who test HIV-positive; (3) facilitated enrollment to care and treatment for those couples with confirmed HIV infection; and (4) for HIV serodiscordant couples, access to PrEP for the HIV-negative partner. A baseline survey, and a follow-up survey approximately 2 weeks later and HIV test, will be administered to all couples involved in the self-testing phase of the study. A cohort of 60 to 70 HIV serodiscordant couples will receive a survey at baseline 6-, 12-, and 18-month survey, and the investigators will collect ongoing clinical data from each clinic visit. Biometric data (fingerprint) will be collected at study and intervention encounters to link utilization of services with survey data. The investigators will also enroll serodiscordant couples from patients already receiving care from the Kisarawe Care and Treatment Center (CTC).

The specific AIMS evaluate 4 key strategic goals, including:

1. HIV Self-Testing for Stable Couples: (a) assess the acceptability, safety, and factors associated with uptake of HIV self-testing; and (b) determine the proportion of clients testing positive for HIV via self-testing who engage in care.
2. Dyadic Engagement of Sero-Discordant Couples in Care & Prevention: (a) establish the proportion of sero-discordant couples who will enroll in HIV care as a dyad, (b) determine the effect of dyadic care enrollment on HIV care retention and ART adherence, and (c) assess reduction in risk of acquiring HIV infection for the negative partner.
3. Pre-Exposure Prophylaxis (PrEP): (a) establish the proportion and characteristics of HIV negative clients in a sero-discordant relationship who opt to take PrEP, (b) determine how engaging in ARV treatment by the positive partner affects PrEP utilization by the negative partner, and vice versa, and (c) Identify patterns and correlates of risk reduction strategies that couples in care utilize over time (abstinence, ARV for positive partner, PrEP for negative partner, condom use).
4. Operational: (a) determine Dyadic-based Diagnosis, Care, & Prevention (DDCP) program cost and economic efficiency, (b) compare DDCP to clinic-based and mobile VCT with regard to cost and efficiency for testing and linkage to care, and (c) assess the feasibility, acceptability, safety, and utility of using biometric data to track service utilization.

Inclusion Criteria:

To be eligible for participation in the self-testing cohort, each individual has to be:

1. age 18 years or older (and at least one member of the couple has to be aged 55 years or below),
2. live in the household regularly,
3. have no plans for moving from the area before the follow up period.

To be eligible for the prevention and care portion of the study, couples must be:

1. in an HIV sero-discordant relationship,
2. pregnant or breastfeeding women will be allowed to enroll in the study after counseling on the risks and benefits is provided,
3. HIV-negative women who are pregnant or breastfeeding will be allowed to take PrEP after counseling on the risks and benefits is provided.

Exclusion Criteria:

Couples will not be eligible for enrolled in the sero-discordant sub-cohort if:

1. the HIV-negative member has signs of advanced kidney disease (measured by serum creatinine),
2. the HIV-negative partner has Hepatitis B and markers of poor liver functioning (measured by alanine aminotransferase).

Cohabitating couples aged 18 to 55 years of age, residing in Kisarawe Town, Tanzania. Our cohort will be comprised of HIV sero-discordant couples.