ESTIMATION OF HIV INCIDENCE IN BRAZIL, 2005-2011

Monday, 18 August 2014
Exhibit hall (Dena'ina Center)
Celia L Szwarcwald, PhD , Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
Paulo R Souza Jr, PhD , Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
Introduction: The HIV incidence is nowadays the most valuable indicator of epidemiologic surveillance, both to guide prevention activities and to monitor ongoing interventions. However, the incidence estimates are still limited to a few countries. This paper addresses a method to estimate the HIV incidence in Brazil in recent years.
Methods: As the information source, we used the national lab information system (SISCEL) created to monitor CD4/CD8 count and viral load among HIV infected people. The proposed method is based on a statistical model that relates the first CD4 count to time of HIV seroconversion. For each treatment-naïve HIV infected case reported in SISCEL aged 15 years or older, we estimated the time lag between HIV infection and the date the case was reported. The HIV incidence was estimated as the sum of the cases reported in the same year of infection, one year after infection, and so on until 20 years after infection.
Results: The average time from HIV infection to date of first CD4 count was 5 years. The proportion of cases reported to SISCEL in the same year of HIV infection increased from 30%, in 2005, to 36%, in 2011.The HIV incidence was estimated as 38968 (95% CI 36805-41130) in 2011, representing approximately 5% of the HIV prevalence. The analysis by gender showed that the HIV incidence increased among men and decreased among women in the period 2005-2011. The male-female incidence ratio was 1.45 in 2005 but increased to 1.96 in 2011.
Conclusions: In the context of expansion of antiretroviral treatment to HIV-infected individuals, and improved survival, it is increasingly difficult to interpret HIV prevalence data, making it essential to have estimates of HIV incidence for a better understanding of the epidemic. The results here depicted suggest that interventions in Brazil should be focused on young adult men.