Background: HIV prevalence has recently declined in several African countries, and prior to this the risk of HIV acquisition per unprotected sex contact also declined in Kenyan sex workers. We hypothesized that heterogeneity in HIV host susceptibility might underpin both of these observations.
Methods: A compartmental mathematical model was used to explore the potential impact of heterogeneity in susceptibility to HIV infection on epidemic behavior, in the absence of other causative mechanisms.
Results: Studies indicated that a substantial heterogeneity in susceptibility to HIV infection may lead to an epidemic that peaks and then declines due to a depletion of the most susceptible individuals, even without changes in sexual behavior. This effect was most notable in high-risk groups such as female sex workers and was consistent with empirical data.
Discussion: Declines in HIV prevalence may have other causes in addition to behavior change, including heterogeneity in host HIV susceptibility. There is a need to further study this heterogeneity and its correlates, particularly as it confounds the ability to attribute HIV epidemic shifts to specific interventions, including behavior change.
aDepartment of Community Medicine, United Arab Emirates University, Al Ain, United Arab Emirates
bDepartment of Medical Microbiology, University of Manitoba, Winnipeg, Canada
cDepartment of Public Health, Erasmus MC, University Medical Center, Rotterdam, the Netherlands
dCenter for Global Health Research, University of Toronto, Toronto, Canada
eNational Microbiology Laboratory, Winnipeg, Canada
fDepartment of Medicine, University Health Network and the University of Toronto, Toronto, Canada
gDepartment of Medical Microbiology, University of Nairobi, Nairobi, Kenya.
Received 17 May, 2008
Revised 4 August, 2008
Accepted 13 August, 2008
Correspondence to Rupert Kaul, MD, PhD, Clinical Sciences Division, #6356 Medical Sciences Building, 1 King's College Circle, Toronto, Ontario M5S1A8, Canada. Tel: +1 416 978 8607; fax: +1 416 978 8765; e-mail: email@example.com