Pathophysiology 21 (2014) 237–256
A public health perspective on HIV/AIDS in Africa: Victories and unmet challenges Michael T. LeVasseur 1 , Neal D. Goldstein 1 , Seth L. Welles ∗ Department of Epidemiology and Biostatistics, Drexel University School of Public Health, Philadelphia, PA, United States
Abstract More than three decades after the first cases of HIV were recognized in the United States and worldwide, Africa remains a remarkable example of both public health successes and remaining challenges. Although many African countries initially lacked the resources and sociopolitical will to advance HIV treatment and prevention strategies, world governments, a committed scientific community, and activists have made tremendous advances. We present a public health perspective on the history of the HIV epidemic in Africa, combining summaries of the epidemiology of HIV infection rates and risk factors for horizontal and vertical HIV transmission, along with a historic perspective on programmatic and funding initiatives that have strongly reduced levels of HIV infection across the continent. In our preparation of this review two clear themes emerged: that (1) the HIV epidemic in Africa remains geographically and culturally heterogeneous, so that treatment and prevention strategies need to be thoughtfully tailored for maximal effectiveness; and (2) a lack of openness to recognize and discuss infection disparities in high risk groups, disseminate prevention information, and enact policies to partner with these highly stigmatized risk groups. This is especially true of female sex workers, people who inject drugs, and men who have sex with men, communities that are often not recognized or typically undercounted when HIV testing and prevention policies are developed by many African governments. Without changes to recognize and de-stigmatize these high-risk groups, a lack of sociopolitical will to alter public health perspectives will likely hinder advances to further curb the HIV epidemic. © 2014 Elsevier Ireland Ltd. All rights reserved.
Keywords: HIV; Africa; Epidemiology; Programmatic advances; Funding strategies; Review
1. Introduction The African AIDS epidemic began like many other infectious disease outbreaks; it started with a few infected individuals and rapidly spread throughout the vulnerable population. In contrast to other epidemics, the outbreaks were not isolated to a particular geographic region or population. Nor were they solely fueled by traditional infectious disease risk factors such as population density, susceptibility and socioeconomic status. Instead, the epidemic tells a dramatic story ∗ Corresponding author at: Department of Epidemiology and Biostatistics, Drexel University School of Public Health, Nesbitt Hall, 3215 Market Street, 5th Floor, Room 535, Philadelphia, PA 19104, United States. Tel.: +1 267 359 6203; fax: +1 267 359 6201. E-mail address: [email protected] (S.L. Welles). 1 Co-first authors.
http://dx.doi.org/10.1016/j.pathophys.2014.07.001 0928-4680/© 2014 Elsevier Ireland Ltd. All rights reserved.
of economic, political, religious, and ideological beliefs that affected an entire continent in vastly different ways. In this review, we explore the successes to date that had a direct impact in reducing morbidity and mortality from AIDS, as well as the unmet challenges that can further reduce the disease burden. As part of the successes we describe interventions that focus on the individual, such as condom use and antiretroviral therapy (e.g., HAART), and interventions that have focused on populations, such as the scale up of access to antiretroviral therapy, male circumcision, and prevention of mother to child transmission. These programs were largely funded by international assistance programs, such as PEPFAR and The Global Fund. We take an epidemiological approach to the discussion; that is, a thorough look at risk factors and characteristics of individuals and populations, and how these impact the diversity of HIV/AIDS through the continent. We initially present a broad picture
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M.T. LeVasseur et al. / Pathophysiology 21 (2014) 237–256
of the epidemic in Africa, then focus on specific microepidemics: focal outbreaks in at-risk populations or geographic areas. In order to examine the interventions, successes, and unmet challenges of HIV/AIDS in Africa the historical conditions and epidemiology that led to such a diverse epidemic are first examined.
2. History and epidemiology Human immunodeficiency virus (HIV) dates back to at least the late 1950s and possibly earlier [1]. Sporadic cases of AIDS-like illnesses were first reported in the 1950s [2], but the epidemic is generally considered to have gained momentum in the early 1980s, coinciding with the first reports of disease in US populations [3]. Although several theories exist as to the origination of HIV infection in humans, it is largely believed that HIV began as a zoonotic infection. The bushmeat theory of HIV posits that zoonotic transmission occurred when non-human primates were slaughtered for food thus exposing hunters to infected blood [4]. Different regions of Africa had different strains of SIV in the nonhuman primate populations and consequently, the serotype of HIV in the human populations in these regions also differ. HIV-1 has been traced to chimpanzees and gorillas in West-Central Africa, while HIV-2 has been traced to sooty mangabeys in West Africa [5]. HIV-1 is largely responsible for the global pandemic of AIDS; HIV-2 has mostly been limited to Western Africa, is less pathogenic compared with HIV-1, and less likely to cause AIDS [6–8]. HIV can further be defined by its groups and subtypes (also known as clades) into specific strains. HIV-1 has four known groups, M, N, O, and a recently identified group P. Group M is by and large the most prevalent circulating clade worldwide, with groups N, O, and P restricted to Central Africa [9]. HIV-2 has eight known groups, A through H, with only groups A and B occurring in humans in Western Africa [9]. Identification of the clade is important for disease epidemiology as well as current and future therapies [10]. The spread of AIDS (colloquially known as “slim disease” from the severe fluid and weight loss [11]) throughout the African continent resulted from multiple overlapping pathways chiefly including migrant workers, military conflict, and commercial sex work [12]. Its transmission occurred mostly via heterosexual contact or mother to child during the perinatal period. Men who have sex with men (MSM) and people who inject drugs (PWID) likely did not contribute in large part to the initial spread of the virus [12], contrary to the US, but the role of these marginalized populations is unclear and limited historical data on these high-risk populations makes estimates of the burden of HIV in these populations difficult [13,14]. Traditional risk factors for HIV infection include horizontal transmission (e.g., unprotected sex, injection drug use, and blood transfusion) and vertical transmission (e.g., pregnancy, birth, and breastfeeding). Horizontal transmission is the
primary mode of infection in adults in Africa [15], while vertical transmission is the primary mode of infection in children in Africa [16,17]. Breastfeeding alone has been estimated to cause up to 50% of all new HIV-1 infections in infants [18]. In sub-Saharan Africa, heterosexual transmission between serodiscordant couples is still the primary risk factor of infection, while in Northern Africa injection drug use and sex work are the primary risk factors [15]. Limited data from Africa on MSM make characterizing this risk factor in terms of the overall role in transmission difficult. Recent evidence from a study done in Nigeria indicates horizontal transmission also occurs to some extent in children, with the primary risk factor being blood transfusion followed by unsterilized sharps and unprotected sex [19]. The changing epidemiology of HIV/AIDS in Africa can be examined through a geographic lens by dividing the country up according to the United Nations geographical sub-regions [20]: Northern, Western, Eastern, Central, and Southern (Fig. 1). The traditionally classified sub-Saharan Africa area includes all sub-regions not included in Northern Africa. In addition to sub-regional differences in HIV infection rates, there are also between-country differences as well as within-country difference, for example urban and rural populations having different risk and exposure profiles. This geographic approach demonstrates the changing prevalence and incidence over time, and how it disproportionately affects certain regions. As of 2012, it is estimated that 25 million adults and children in Sub-Saharan Africa and 260,000 adults and children in the Middle East and North Africa are living with HIV. It is also estimated that 1.6 million adults and children in Sub-Saharan Africa and 32,000 adults and children in the Middle East and North Africa were infected with HIV in 2012. These numbers include 2.9 million infected children in Sub-Saharan Africa and 230,000 infected children in the Middle East and North Africa who were under the age of 15 [21]. Among the priority nations in Sub-Saharan Africa identified in the UNAIDS “Global Plan Towards the Elimination of New HIV Infections Among Children by 2015 and Keeping their Mothers Alive,” there were an estimated 210,000 pediatric infections resulting from mother-to-child transmission in 2012. This represents a 37% reduction in mother-tochild transmission in three years [22]. These figures become even more dramatic when examined on a per-country basis (Table 1) and show the disparity of microepidemics in Africa. Table 1 summarizes the changing HIV prevalence (ages 15–49) and incidence (all ages) in select countries from each sub-region based on the 2013 UNAIDS global report [23]. Prevalence, or measure of proportion of population affected with HIV or AIDS at one point in time, provides a glimpse into the burden of disease, while cumulative incidence, a measure of the proportion of new cases per the country’s population, provides an idea of the control of disease. Prevalence and incidence can change independent of each other. For example, prevalence may increase as individuals living with HIV live longer. Prevalence may also decrease based on
M.T. LeVasseur et al. / Pathophysiology 21 (2014) 237–256
239
Table 1 Incidence, prevalence, and percent change of HIV in Africa by sub-region: 2001 and 2012. Prevalence proportion (%)
Northern Algeria Egypt Libya Morocco Sudan Tunisia Sub-Saharan Western Benin Burkina Faso Cabo Verde Côte d’Ivoire The Gambia Ghana Guinea Guinea-Bissau Liberia Mali Mauritania Niger Nigeria Senegal Sierra Leone Togo Eastern Burundi Comoros Djibouti Eritrea Ethiopia Kenya Madagascar Malawi Mauritius Mozambique Rwanda Somalia South Sudan Uganda United Republic of Tanzania Zambia Zimbabwe Central Angola Cameroon Central African Republic Chad Congo Democratic Republic of the Congo Equatorial Guinea Gabon Sao Tome and Principe Southern Botswana Lesotho Namibia South Africa Swaziland
Cumulative incidence (%)
2001
2012
2001
2012
% Change
–
A public health perspective on HIV/AIDS in Africa: Victories and unmet challenges Michael T. LeVasseur 1 , Neal D. Goldstein 1 , Seth L. Welles ∗ Department of Epidemiology and Biostatistics, Drexel University School of Public Health, Philadelphia, PA, United States
Abstract More than three decades after the first cases of HIV were recognized in the United States and worldwide, Africa remains a remarkable example of both public health successes and remaining challenges. Although many African countries initially lacked the resources and sociopolitical will to advance HIV treatment and prevention strategies, world governments, a committed scientific community, and activists have made tremendous advances. We present a public health perspective on the history of the HIV epidemic in Africa, combining summaries of the epidemiology of HIV infection rates and risk factors for horizontal and vertical HIV transmission, along with a historic perspective on programmatic and funding initiatives that have strongly reduced levels of HIV infection across the continent. In our preparation of this review two clear themes emerged: that (1) the HIV epidemic in Africa remains geographically and culturally heterogeneous, so that treatment and prevention strategies need to be thoughtfully tailored for maximal effectiveness; and (2) a lack of openness to recognize and discuss infection disparities in high risk groups, disseminate prevention information, and enact policies to partner with these highly stigmatized risk groups. This is especially true of female sex workers, people who inject drugs, and men who have sex with men, communities that are often not recognized or typically undercounted when HIV testing and prevention policies are developed by many African governments. Without changes to recognize and de-stigmatize these high-risk groups, a lack of sociopolitical will to alter public health perspectives will likely hinder advances to further curb the HIV epidemic. © 2014 Elsevier Ireland Ltd. All rights reserved.
Keywords: HIV; Africa; Epidemiology; Programmatic advances; Funding strategies; Review
1. Introduction The African AIDS epidemic began like many other infectious disease outbreaks; it started with a few infected individuals and rapidly spread throughout the vulnerable population. In contrast to other epidemics, the outbreaks were not isolated to a particular geographic region or population. Nor were they solely fueled by traditional infectious disease risk factors such as population density, susceptibility and socioeconomic status. Instead, the epidemic tells a dramatic story ∗ Corresponding author at: Department of Epidemiology and Biostatistics, Drexel University School of Public Health, Nesbitt Hall, 3215 Market Street, 5th Floor, Room 535, Philadelphia, PA 19104, United States. Tel.: +1 267 359 6203; fax: +1 267 359 6201. E-mail address: [email protected] (S.L. Welles). 1 Co-first authors.
http://dx.doi.org/10.1016/j.pathophys.2014.07.001 0928-4680/© 2014 Elsevier Ireland Ltd. All rights reserved.
of economic, political, religious, and ideological beliefs that affected an entire continent in vastly different ways. In this review, we explore the successes to date that had a direct impact in reducing morbidity and mortality from AIDS, as well as the unmet challenges that can further reduce the disease burden. As part of the successes we describe interventions that focus on the individual, such as condom use and antiretroviral therapy (e.g., HAART), and interventions that have focused on populations, such as the scale up of access to antiretroviral therapy, male circumcision, and prevention of mother to child transmission. These programs were largely funded by international assistance programs, such as PEPFAR and The Global Fund. We take an epidemiological approach to the discussion; that is, a thorough look at risk factors and characteristics of individuals and populations, and how these impact the diversity of HIV/AIDS through the continent. We initially present a broad picture
238
M.T. LeVasseur et al. / Pathophysiology 21 (2014) 237–256
of the epidemic in Africa, then focus on specific microepidemics: focal outbreaks in at-risk populations or geographic areas. In order to examine the interventions, successes, and unmet challenges of HIV/AIDS in Africa the historical conditions and epidemiology that led to such a diverse epidemic are first examined.
2. History and epidemiology Human immunodeficiency virus (HIV) dates back to at least the late 1950s and possibly earlier [1]. Sporadic cases of AIDS-like illnesses were first reported in the 1950s [2], but the epidemic is generally considered to have gained momentum in the early 1980s, coinciding with the first reports of disease in US populations [3]. Although several theories exist as to the origination of HIV infection in humans, it is largely believed that HIV began as a zoonotic infection. The bushmeat theory of HIV posits that zoonotic transmission occurred when non-human primates were slaughtered for food thus exposing hunters to infected blood [4]. Different regions of Africa had different strains of SIV in the nonhuman primate populations and consequently, the serotype of HIV in the human populations in these regions also differ. HIV-1 has been traced to chimpanzees and gorillas in West-Central Africa, while HIV-2 has been traced to sooty mangabeys in West Africa [5]. HIV-1 is largely responsible for the global pandemic of AIDS; HIV-2 has mostly been limited to Western Africa, is less pathogenic compared with HIV-1, and less likely to cause AIDS [6–8]. HIV can further be defined by its groups and subtypes (also known as clades) into specific strains. HIV-1 has four known groups, M, N, O, and a recently identified group P. Group M is by and large the most prevalent circulating clade worldwide, with groups N, O, and P restricted to Central Africa [9]. HIV-2 has eight known groups, A through H, with only groups A and B occurring in humans in Western Africa [9]. Identification of the clade is important for disease epidemiology as well as current and future therapies [10]. The spread of AIDS (colloquially known as “slim disease” from the severe fluid and weight loss [11]) throughout the African continent resulted from multiple overlapping pathways chiefly including migrant workers, military conflict, and commercial sex work [12]. Its transmission occurred mostly via heterosexual contact or mother to child during the perinatal period. Men who have sex with men (MSM) and people who inject drugs (PWID) likely did not contribute in large part to the initial spread of the virus [12], contrary to the US, but the role of these marginalized populations is unclear and limited historical data on these high-risk populations makes estimates of the burden of HIV in these populations difficult [13,14]. Traditional risk factors for HIV infection include horizontal transmission (e.g., unprotected sex, injection drug use, and blood transfusion) and vertical transmission (e.g., pregnancy, birth, and breastfeeding). Horizontal transmission is the
primary mode of infection in adults in Africa [15], while vertical transmission is the primary mode of infection in children in Africa [16,17]. Breastfeeding alone has been estimated to cause up to 50% of all new HIV-1 infections in infants [18]. In sub-Saharan Africa, heterosexual transmission between serodiscordant couples is still the primary risk factor of infection, while in Northern Africa injection drug use and sex work are the primary risk factors [15]. Limited data from Africa on MSM make characterizing this risk factor in terms of the overall role in transmission difficult. Recent evidence from a study done in Nigeria indicates horizontal transmission also occurs to some extent in children, with the primary risk factor being blood transfusion followed by unsterilized sharps and unprotected sex [19]. The changing epidemiology of HIV/AIDS in Africa can be examined through a geographic lens by dividing the country up according to the United Nations geographical sub-regions [20]: Northern, Western, Eastern, Central, and Southern (Fig. 1). The traditionally classified sub-Saharan Africa area includes all sub-regions not included in Northern Africa. In addition to sub-regional differences in HIV infection rates, there are also between-country differences as well as within-country difference, for example urban and rural populations having different risk and exposure profiles. This geographic approach demonstrates the changing prevalence and incidence over time, and how it disproportionately affects certain regions. As of 2012, it is estimated that 25 million adults and children in Sub-Saharan Africa and 260,000 adults and children in the Middle East and North Africa are living with HIV. It is also estimated that 1.6 million adults and children in Sub-Saharan Africa and 32,000 adults and children in the Middle East and North Africa were infected with HIV in 2012. These numbers include 2.9 million infected children in Sub-Saharan Africa and 230,000 infected children in the Middle East and North Africa who were under the age of 15 [21]. Among the priority nations in Sub-Saharan Africa identified in the UNAIDS “Global Plan Towards the Elimination of New HIV Infections Among Children by 2015 and Keeping their Mothers Alive,” there were an estimated 210,000 pediatric infections resulting from mother-to-child transmission in 2012. This represents a 37% reduction in mother-tochild transmission in three years [22]. These figures become even more dramatic when examined on a per-country basis (Table 1) and show the disparity of microepidemics in Africa. Table 1 summarizes the changing HIV prevalence (ages 15–49) and incidence (all ages) in select countries from each sub-region based on the 2013 UNAIDS global report [23]. Prevalence, or measure of proportion of population affected with HIV or AIDS at one point in time, provides a glimpse into the burden of disease, while cumulative incidence, a measure of the proportion of new cases per the country’s population, provides an idea of the control of disease. Prevalence and incidence can change independent of each other. For example, prevalence may increase as individuals living with HIV live longer. Prevalence may also decrease based on
M.T. LeVasseur et al. / Pathophysiology 21 (2014) 237–256
239
Table 1 Incidence, prevalence, and percent change of HIV in Africa by sub-region: 2001 and 2012. Prevalence proportion (%)
Northern Algeria Egypt Libya Morocco Sudan Tunisia Sub-Saharan Western Benin Burkina Faso Cabo Verde Côte d’Ivoire The Gambia Ghana Guinea Guinea-Bissau Liberia Mali Mauritania Niger Nigeria Senegal Sierra Leone Togo Eastern Burundi Comoros Djibouti Eritrea Ethiopia Kenya Madagascar Malawi Mauritius Mozambique Rwanda Somalia South Sudan Uganda United Republic of Tanzania Zambia Zimbabwe Central Angola Cameroon Central African Republic Chad Congo Democratic Republic of the Congo Equatorial Guinea Gabon Sao Tome and Principe Southern Botswana Lesotho Namibia South Africa Swaziland
Cumulative incidence (%)
2001
2012
2001
2012
% Change
–
