Aim 1: To examine longitudinally the prevalence and incidence of HIV, Chlamydia, gonorrhea, and syphilis.

Aim 2: To examine longitudinally self-reported HIV risk behaviors (e.g., rates of unprotected vaginal and anal sex across all partners, proportion of condom protected sex, number and type of sexual partners).

Aim 3: To examine how Aims 1 and 2 vary by nationality, ethnicity, and key migration attributes (migrant versus nonmigrant, frequency and length of trips outside the country, etc.)

Aim 4: To identify and estimate the causal impact of migration attributes posited to influence HIV/STIs and sexual HIV risk behaviors. We will examine the temporal associations between key migration attributes and new cases of STIs and sexual HIV risk behaviors after taking into account the following factors: