Exploring the HIV epidemic among key populations in Latin America
Author(s)
Bórquez, Annick
Type
Thesis
Abstract
The work is focussed on the HIV epidemic among key populations in Latin America, a region
that has received limited international attention due to the concentrated nature of its
epidemic. It faces important challenges in prevention and risks missing the opportunity to
control the epidemic. Despite the evidence available showing the disproportionate burden
of infection among key populations, principally men who have sex with men (MSM) and to a
lesser extent injecting drug users (IDU) and female sex workers (FSW), a small percentage of
countries’ HIV prevention spending is allocated towards prevention interventions among
these groups.
In this thesis, we first estimate the distribution of new infections by type of exposure in the
Dominican Republic, Mexico and Peru and find that MSM account for a large share of new
infections in the three countries (over 50% in Mexico and Peru and 30% in Dominican
Republic). This highlights that this population should be prioritised in prevention
programmes. We then turn to interventions for MSM, and investigate whether pre-exposure
prophylaxis (PrEP) to prevent HIV acquisition among MSM in Lima, Peru represents a cost-effective
intervention at the population level. We find PrEP to be a potentially cost-effective
intervention although unaffordable at a large scale. We conclude it should be considered as
an additional tool within a combination prevention approach among this population.
Following these, we seek to understand the dynamics, causes and consequences of risk
behaviours and HIV infection in another key population that has rarely been prioritised by
public health programmes: prison inmates. We use data from the largest prison in Peru and
find that HIV prevalence is 4 times higher than national prevalence and inmates engage in
riskier sexual behaviours than in the general population. Nevertheless, there are indications
of risk behaviours and HIV prevalence reducing in recent years. To help direct prevention
efforts in this setting, we characterise the risk profile of inmates who engaged in sex with
FSW, other men and in unprotected sex with casual partners and identify inmates who have
sex with men as being at heightened risk of infection (due to higher levels of drug use and
unprotected sex).
We use those data to develop a mathematical model that represents the HIV epidemic in the
prison. Contrary to expectations, we find that incidence is likely to be less than 1% per year
within the prison and that the dynamics of HIV in prisons are principally driven by inmates
infected before their incarceration. We further estimate that since the beginning of the
epidemic, at least 5% of HIV cases identified in Lima have passed through the prison,
suggesting that the routine screening system in place at prisons could make a substantial
contribution to controlling the HIV epidemic across the city.
Finally, we formulate a conceptual framework of HIV risk among prison inmates in Latin
America focussing on the social and underlying determinants of risk and develop a
structured questionnaire to test the hypotheses proposed through the framework and
obtain information relevant to the design of interventions within prisons and at the
community level.
Together this work draws on social and quantitative science to provide new insights into key
populations in Latin America that should contribute to stronger and responsive HIV
prevention programmes, to the benefit of all those that remain at risk of HIV in the region.
that has received limited international attention due to the concentrated nature of its
epidemic. It faces important challenges in prevention and risks missing the opportunity to
control the epidemic. Despite the evidence available showing the disproportionate burden
of infection among key populations, principally men who have sex with men (MSM) and to a
lesser extent injecting drug users (IDU) and female sex workers (FSW), a small percentage of
countries’ HIV prevention spending is allocated towards prevention interventions among
these groups.
In this thesis, we first estimate the distribution of new infections by type of exposure in the
Dominican Republic, Mexico and Peru and find that MSM account for a large share of new
infections in the three countries (over 50% in Mexico and Peru and 30% in Dominican
Republic). This highlights that this population should be prioritised in prevention
programmes. We then turn to interventions for MSM, and investigate whether pre-exposure
prophylaxis (PrEP) to prevent HIV acquisition among MSM in Lima, Peru represents a cost-effective
intervention at the population level. We find PrEP to be a potentially cost-effective
intervention although unaffordable at a large scale. We conclude it should be considered as
an additional tool within a combination prevention approach among this population.
Following these, we seek to understand the dynamics, causes and consequences of risk
behaviours and HIV infection in another key population that has rarely been prioritised by
public health programmes: prison inmates. We use data from the largest prison in Peru and
find that HIV prevalence is 4 times higher than national prevalence and inmates engage in
riskier sexual behaviours than in the general population. Nevertheless, there are indications
of risk behaviours and HIV prevalence reducing in recent years. To help direct prevention
efforts in this setting, we characterise the risk profile of inmates who engaged in sex with
FSW, other men and in unprotected sex with casual partners and identify inmates who have
sex with men as being at heightened risk of infection (due to higher levels of drug use and
unprotected sex).
We use those data to develop a mathematical model that represents the HIV epidemic in the
prison. Contrary to expectations, we find that incidence is likely to be less than 1% per year
within the prison and that the dynamics of HIV in prisons are principally driven by inmates
infected before their incarceration. We further estimate that since the beginning of the
epidemic, at least 5% of HIV cases identified in Lima have passed through the prison,
suggesting that the routine screening system in place at prisons could make a substantial
contribution to controlling the HIV epidemic across the city.
Finally, we formulate a conceptual framework of HIV risk among prison inmates in Latin
America focussing on the social and underlying determinants of risk and develop a
structured questionnaire to test the hypotheses proposed through the framework and
obtain information relevant to the design of interventions within prisons and at the
community level.
Together this work draws on social and quantitative science to provide new insights into key
populations in Latin America that should contribute to stronger and responsive HIV
prevention programmes, to the benefit of all those that remain at risk of HIV in the region.
Date Issued
2012-09
Date Awarded
2013-03
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Hallett, Timothy
Garnett, Geoffrey
Sponsor
Medical Research Council (Great Britain)
Publisher Department
School of Public Health
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)