Are slum dwellers at heightened risk of HIV infection than other urban residents? Evidence from population-based HIV prevalence surveys in Kenya

► HIV prevalence in Nairobi slums is 12%, compared with 5% among non-slum urban residents, and 6% in rural areas. ► HIV prevalence in Kenyan urban areas is principally fuelled by very high HIV infection rates in slum areas. ► Women who have first sexual intercourse at early ages are at increased risk of becoming HIV infected. ► In Kenya there are strong patterns of HIV infection by ethnicity but living in urban areas dilutes this effect.