Larry Sawers

Concurrent sexual partnerships do not explain the HIV epidemics in Africa: a systematic review of the evidence

The notion that concurrent sexual partnerships are especially common in sub-Saharan Africa and explain the regions high HIV prevalence is accepted by many as conventional wisdom. In this paper, we evaluate the quantitative and qualitative evidence offered by the principal proponents of the concurrency hypothesis and analyze the mathematical model they use to establish the plausibility of the hypothesis.We find that research seeking to establish a statistical correlation between concurrency and HIV prevalence either finds no correlation or has important limitations. Furthermore, in order to simulate rapid spread of HIV, mathematical models require unrealistic assumptions about frequency of sexual contact, gender symmetry, levels of concurrency, and per-act transmission rates. Moreover, quantitative evidence cited by proponents of the concurrency hypothesis is unconvincing since they exclude Demographic and Health Surveys and other data showing that concurrency in Africa is low, make broad statements about non-African concurrency based on very few surveys, report data incorrectly, report data from studies that have no information about concurrency as though they supported the hypothesis, report incomparable data and cite unpublished or unavailable studies. Qualitative evidence offered by proponents of the hypothesis is irrelevant since, among other reasons, there is no comparison of Africa with other regions.Promoters of the concurrency hypothesis have failed to establish that concurrency is unusually prevalent in Africa or that the kinds of concurrent partnerships found in Africa produce more rapid spread of HIV than other forms of sexual behaviour. Policy makers should turn attention to drivers of African HIV epidemics that are policy sensitive and for which there is substantial epidemiological evidence.

HIV and concurrent sexual partnerships: modelling the role of coital dilution

BackgroundThe concurrency hypothesis asserts that high prevalence of overlapping sexual partnerships explains extraordinarily high HIV levels in sub-Saharan Africa. Earlier simulation models show that the network effect of concurrency can increase HIV incidence, but those models do not account for the coital dilution effect (non-primary partnerships have lower coital frequency than primary partnerships).MethodsWe modify the model of Eaton et al (AIDS and Behavior, September 2010) to incorporate coital dilution by assigning lower coital frequencies to non-primary partnerships. We parameterize coital dilution based on the empirical work of Morris et al (PLoS ONE, December 2010) and others. Following Eaton et al, we simulate the daily transmission of HIV over 250 years for 10 levels of concurrency.ResultsAt every level of concurrency, our focal coital-dilution simulation produces epidemic extinction. Our sensitivity analysis shows that this result is quite robust; even modestly lower coital frequencies in non-primary partnerships lead to epidemic extinction.ConclusionsIn order to contribute usefully to the investigation of HIV prevalence, simulation models of concurrent partnering and HIV epidemics must incorporate realistic degrees of coital dilution. Doing so dramatically reduces the role that concurrency can play in accelerating the spread of HIV and suggests that concurrency cannot be an important driver of HIV epidemics in sub-Saharan Africa. Alternative explanations for HIV epidemics in sub-Saharan Africa are needed.

Measuring and Modelling Concurrency

This article explores three critical topics discussed in the recent debate over concurrency (overlapping sexual partnerships): measurement of the prevalence of concurrency, mathematical modelling of concurrency and HIV epidemic dynamics, and measuring the correlation between HIV and concurrency. The focus of the article is the concurrency hypothesis – the proposition that presumed high prevalence of concurrency explains sub‐Saharan Africas exceptionally high HIV prevalence. Recent surveys using improved questionnaire design show reported concurrency ranging from 0.8% to 7.6% in the region. Even after adjusting for plausible levels of reporting errors, appropriately parameterized sexual network models of HIV epidemics do not generate sustainable epidemic trajectories (avoid epidemic extinction) at levels of concurrency found in recent surveys in sub‐Saharan Africa. Efforts to support the concurrency hypothesis with a statistical correlation between HIV incidence and concurrency prevalence are not yet successful. Two decades of efforts to find evidence in support of the concurrency hypothesis have failed to build a convincing case.

Nontraditional or New Traditional Exports: Ecuador's Flower Boom

This article explores the sources of Ecuadors boom in flower exports since the late 1980s. In that boom, fresh cut flower exports rose from almost nothing to 9 percent of the countrys nonpetroleum export earnings. This research addresses whether trade liberalization and macroeconomic reforms played a decisive role in stimulating the export boom or whether changes in the global flower market created Ecuadors comparative advantage in flower exports independent of the policy regime. The article surveys the many changes in economic policy toward agriculture in general, flower cultivation, nontraditional exports, international trade, and macroeconomic stability. Growth rates in traditional and nontraditional exports are examined to see if they correlate with changes in key policies. The article also examines how the restructuring of the global flower market affected Ecuadors floriculture industry. Este artículo explora el origen del auge de la exportación de flores del Ecuador desde los últimos años de la década del 80. En este auge, las exportaciones de flores frescas crecieron hasta constituir un 9 por ciento de las ganancias de las exportaciones no petroleras. Esta investigación se propone examinar si la liberalización del comercio y las reformas macroeconómicas jugaron un papel decisivo en el impulso del auge exportador, ó si cambios en el mercado internacional de flores crearon la ventaja comparativa del Ecuador independientemente del régimen de las políticas económicas. Este artículo examina la gran cantidad de cambios en la política económica hacia el sector agricultor en general, en el cultivo de las flores, en las exportaciones no tradicionales, en el comercio internacional y en la estabilidad macroeconómica. A su vez, se examina el ritmo de crecimiento de las exportaciones tradicionales y no tradicionales para determinar si ambos se correlacionan con los cambios en políticas claves. Por último, este artículo también examina de qué manera la reestructuración del mercado internacional de flores afectó la industria de la floricultura ecuatoriana.

Cofactor Infections and HIV Epidemics in Developing Countries: Implications for Treatment

Abstract This article shows that the burden of certain tropical disease infections, after controlling for other factors, is positively correlated with HIV prevalence. Using cross-national data and multivariate linear regression analysis, we investigate the determinants of HIV prevalence in low- and middle-income countries. We begin with social and economic variables used in other cross-national studies and then incorporate data on parasitic and infectious diseases endemic in poor populations, which are found to be strongly and significantly correlated with – and are potent predictors of – HIV prevalence. The paper concludes by arguing that treating tropical diseases may be a cost-effective add-on to HIV-prevention and -treatment programs, thus slowing the spread of HIV in disease-burdened populations.

Urban Primacy in Tanzania

Dissatisfaction with the regional distribution of population and employment is nearly universal among Third World policymakers. In particular, the overwhelming economic, social, demographic, and political dominance of the largest city-its primacy-is believed to sap the development potential of the entire country as well as present insurmountable problems from excessively rapid growth of the primate city itself. Yet few governments have moved vigorously against urban primacy. Tanzania has been considered one of the few exceptions to this rule. This article describes and evaluates urban and regional planning in Tanzania aimed at reducing the dominance of Dar es Salaam in the urban hierarchy. The conclusion of this research is that Tanzania has been largely unsuccessful in preventing or even slowing the growth of Dar es Salaam. Indeed, by some measures primacy in the Tanzania urban hierarchy has increased since the antiprimacy policies were first implemented. Various steps were taken by the government beginning in 1969 as part of a comprehensive program to reduce Dar es Salaams primacy. Investment funds were allocated to several growth poles throughout the country. Prices for consumer goods as well as prices paid to farmers for their crops were made uniform throughout the country to encourage growth in remote areas. The government was reorganized to bring the planning and administrative functions closer to the regions and to lessen the role of the capital city. This government reorganization was also designed to allocate social welfare spending more evenly across the country. Primary education became virtually universal, health clinics were built in many towns, and the announced goal was to supply piped water to every village in the country. Plans were revealed to move the capital itself to the interior town of Dodoma. The government forcibly deported residents of Dar es Salaam who had no formalsector employment in an attempt to reduce the citys population. Despite the innovative, far-ranging, and often discussed efforts by

Rush to judgment: the STI-treatment trials and HIV in sub-Saharan Africa.

The extraordinarily high incidence of HIV in sub‐Saharan Africa led to the search for cofactor infections that could explain the high rates of transmission in the region. Genital inflammation and lesions caused by sexually transmitted infections (STIs) were a probable mechanism, and numerous observational studies indicated several STI cofactors. Nine out of the ten randomized controlled trials (RCTs), however, failed to demonstrate that treating STIs could lower HIV incidence. We evaluate all 10 trials to determine if their design permits the conclusion, widely believed, that STI treatment is ineffective in reducing HIV incidence.

Congenital toxoplasmosis in Austria: Prenatal screening for prevention is cost-saving

Background Primary infection of Toxoplasma gondii during pregnancy can be transmitted to the unborn child and may have serious consequences, including retinochoroiditis, hydrocephaly, cerebral calcifications, encephalitis, splenomegaly, hearing loss, blindness, and death. Austria, a country with moderate seroprevalence, instituted mandatory prenatal screening for toxoplasma infection to minimize the effects of congenital transmission. This work compares the societal costs of congenital toxoplasmosis under the Austrian national prenatal screening program with the societal costs that would have occurred in a No-Screening scenario. Methodology/Principal findings We retrospectively investigated data from the Austrian Toxoplasmosis Register for birth cohorts from 1992 to 2008, including pediatric long-term follow-up until May 2013. We constructed a decision-analytic model to compare lifetime societal costs of prenatal screening with lifetime societal costs estimated in a No-Screening scenario. We included costs of treatment, lifetime care, accommodation of injuries, loss of life, and lost earnings that would have occurred in a No-Screening scenario and compared them with the actual costs of screening, treatment, lifetime care, accommodation, loss of life, and lost earnings. We replicated that analysis excluding loss of life and lost earnings to estimate the budgetary impact alone. Our model calculated total lifetime costs of €103 per birth under prenatal screening as carried out in Austria, saving €323 per birth compared with No-Screening. Without screening and treatment, lifetime societal costs for all affected children would have been €35 million per year; the implementation costs of the Austrian program are less than €2 million per year. Calculating only the budgetary impact, the national program was still cost-saving by more than €15 million per year and saved €258 million in 17 years. Conclusions/Significance Cost savings under a national program of prenatal screening for toxoplasma infection and treatment are outstanding. Our results are of relevance for health care providers by supplying economic data based on a unique national dataset including long-term follow-up of affected infants.

Economic Costs and Benefits of a Community-Based Lymphedema Management Program for Lymphatic Filariasis in Odisha State, India

Lymphatic filariasis afflicts 68 million people in 73 countries, including 17 million persons living with chronic lymphedema. The Global Programme to Eliminate Lymphatic Filariasis aims to stop new infections and to provide care for persons already affected, but morbidity management programs have been initiated in only 24 endemic countries. We examine the economic costs and benefits of alleviating chronic lymphedema and its effects through a simple limb-care program. For Khurda District, Odisha State, India, we estimated lifetime medical costs and earnings losses due to chronic lymphedema and acute dermatolymphangioadenitis (ADLA) with and without a community-based limb-care program. The program would reduce economic costs of lymphedema and ADLA over 60 years by 55%. Savings of US

Urban Planning in the Soviet Union and China

1,648 for each affected person in the workforce are equivalent to 1,258 days of labor. Per-person savings are more than 130 times the per-person cost of the program. Chronic lymphedema and ADLA impose a substantial physical and economic burden on the population in filariasis-endemic areas. Low-cost programs for lymphedema management based on limb washing and topical medication for infection are effective in reducing the number of ADLA episodes and stopping progression of disabling and disfiguring lymphedema. With reduced disability, people are able to work longer hours, more days per year, and in more strenuous, higher-paying jobs, resulting in an important economic benefit to themselves, their families, and their communities. Mitigating the severity of lymphedema and ADLA also reduces out-of-pocket medical expense.