Predicted impact of the HIV-1 epidemic on measles in developing countries: results from a dynamic age-structured model.

BACKGROUND: Although measles incidence has been reduced to low levels in many countries, the potential exists for HIV-1 infection to enhance measles virus (MV) transmission and hinder measles control and elimination efforts. METHODS: HIV-1 infection was incorporated into an age-structured, deterministic compartmental model of MV transmission. Parameter estimates were obtained from published studies. The model was then adapted to simulate the introduction of antiretroviral therapy (ART). RESULTS: The model suggests that prior to the introduction of ART, HIV-1 infection has little impact on the transmission dynamics of MV. High mortality rates in HIV-1-infected children without access to ART counteract the higher rates of vaccine failure, shorter duration of maternal antibody protection and longer duration of infectiousness in HIV-1-infected children, as many of these children die before they are able to contribute to MV transmission. The introduction of ART into the model resulted in an increase in measles prevalence. CONCLUSIONS: High overall mortality among HIV-1-infected children without access to ART limits the impact of the HIV-1 epidemic on MV transmission and may help to explain the initial success of measles control strategies in Africa. The scaling-up of ART should improve children's survival but could lead to an increase in measles prevalence in the absence of sustained measles control efforts. Further study of the duration of immunity in HIV-1-infected children receiving ART and their response to revaccination is needed to determine whether a second dose of measles vaccine will protect these children and further reduce MV transmission