Effect of HSV‐2 on population‐level trends in HIV incidence in Uganda between 1990 and 2007

Samuel Biraro,Helen A Weiss,Richard White,Anatoli Kamali,Alex Karabarinde,Juliet Nsiimire Ssendagala,Heiner Grosskurth

doi:10.1111/tmi.12176

Abstract

Objective To assess the long-term effects of population-level HSV-2 infection on HIV incidence.Methods Data from a population-based cohort in south-western Uganda were used to estimate HIV incidence from 1990 to 2007. Stored blood samples were tested for HSV-2, and the impact of HSV-2 prevalence and incidence on HIV incidence was estimated by calculating population attributable fractions (PAFs). The association between population-level annual HIV incidence and annual HSV-2 incidence/prevalence was analysed using linear regression.Results HIV incidence declined over time among men, from 8.72/1000 person-years (pyr) in 1990 to 4.85/1000 pyr in 2007 (P-trend <0.001). In contrast, there was no decline in HIV incidence among women (4.86/1000 pyr in 1990 to 6.74/1000 pyr in 2007, P-trend = 0.18). PAFs of incident HIV attributable to HSV-2 were high (60% in males; 70% in females). There was no evidence of an association between long-term trends in HIV incidence and HSV-2 prevalence or incidence.Conclusion Assuming a causal relationship, a substantial proportion of new HIV infections in this population are attributable to HSV-2. The study did not find an effect of HSV-2 prevalence/incidence on trends in HIV incidence. HIV incidence did not vary much during the study period. This may partly explain the lack of association.

Highlights

Few African population-based studies have reported trends in HIV incidence over time (Shafer et al 2008)
Direct estimates of HIV incidence are useful measures of progress in HIV prevention, as unlike HIV prevalence estimates, they do not depend on treatment and mortality parameters (Mahy et al 2009; Joint United Nations Programme on HIV/AIDS (UNAIDS) & The Global HIV/AIDS Program (GHAP) The World Bank 2009)
We report results from a long-term population-based cohort in rural south-western Uganda to directly estimate incidence from 1990 to 2007 and to examine the association between HSV-2 infection and risk of HIV acquisition in this population

Summary

Introduction

Few African population-based studies have reported trends in HIV incidence over time (Shafer et al 2008). Mathematical models have estimated that, in a mature HIV epidemic, HSV-2 infection may account for 25–50% of new HIV infections (Freeman et al 2007; Abu-Raddad et al 2008), that a hypothetical prophylactic HSV-2 vaccine may reduce HIV incidence by 30–40% after 20 years (Freeman et al 2009), and that long-term HSV2 suppressive therapy may reduce risk of onward transmission of HIV and reduce HIV incidence by 30% (White et al 2008) These studies reflect the potential of effective HSV-2 control on HIV incidence. We estimate the proportion of new HIV infections attributable to HSV-2 infection and analyse the association

Methods

Results

Conclusion