Sawers, Larry (Dept. of Economics)

Cofactor Infections and HIV Epidemics in Developing Countries: Implications for Treatment
Working Paper No. 2008-03. 15 pages., 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 crossnational 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 addon to HIV prevention and treatment programs, thus slowing the spread of HIV in disease-burdened populations., Submitted by Chris Lewis (clewis@american.edu) on 2009-02-20T21:27:29Z No. of bitstreams: 1 2008-03.pdf: 135302 bytes, checksum: 94205e5eebaedbb39528e6961cf134e0 (MD5), Made available in DSpace on 2009-02-20T21:27:29Z (GMT). No. of bitstreams: 1 2008-03.pdf: 135302 bytes, checksum: 94205e5eebaedbb39528e6961cf134e0 (MD5) Previous issue date: 2008, Department of Economics, American University; Gettysburg College
Concurrent sexual partnerships do not explain the HIV epidemics in Africa: a systematic review of the evidence
Sawers and Stillwaggon Journal of the International AIDS Society 2010, 13:34 http://www.jiasociety.org/content/13/1/34, The notion that concurrent sexual partnerships are especially common in sub-Saharan Africa and explain the region’s 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 concur- rency, 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 con- currency 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.
Econometric Problems in Analyzing the Mule in Southern Agriculture
Working paper No. 2004-14. Nine pages., Submitted by Chris Lewis (clewis@american.edu) on 2009-02-18T15:03:56Z No. of bitstreams: 1 2004-14.pdf: 180610 bytes, checksum: 0b01a6ac1f947b81d3c1278f00c54436 (MD5), Made available in DSpace on 2009-02-18T15:03:56Z (GMT). No. of bitstreams: 1 2004-14.pdf: 180610 bytes, checksum: 0b01a6ac1f947b81d3c1278f00c54436 (MD5) Previous issue date: 2004-11, Department of Economics, American University
HIV and concurrent sexual partnerships
HIV and concurrent sexual partnerships
Published in: Journal of the International AIDS Society, 2011, 14:44 https://doi.org/10.1186/1758-2652-14-44
Measuring and modelling concurrency
This article is a review of the recent debate over the concurrency hypothesis—the proposition that overlapping sexual partnerships explain sub-Saharan Africa’s extraordinary HIV epidemics. Early efforts to model HIV epidemic dynamics and sexual networks substantially overstated the importance of concurrency. Recent models, including our own, show that concurrent sexual partners cannot explain contemporary HIV epidemics in eastern and southern Africa or track the early dramatic rise in HIV prevalence during the 1980s and 1990s. Survey data, including from recent surveys, show that the prevalence of concurrency is too low to explain the growth of HIV epidemics. The prevalence of concurrency and HIV do not correlate within or across countries or regions. Recent attempts to demonstrate such a correlation using the share of outside infections among total seroconversions in stable couples draws inferences that are not valid. Participants in the recent debate over concurrency disagree over the importance of coinfections in HIV epidemics in sub-Saharan Africa. Twenty-one recently published articles address the issue of concurrency. None them provides evidence for the concurrency hypothesis and many of them seriously erode the already weak case for the hypothesis. That finding has important implications for future research and HIV-prevention and treatment policy.
Nontraditional or New Traditional Exports: Ecuador’s Flower Boom
Working Paper No. 2004-13. 32 pages., This article seeks to explore the sources of the boom in flower exports from Ecuador in the last fifteen years. Rising from almost nothing in the late 1980s, fresh cut flowers now account for 8 percent of the country’s nonpetroleum export earnings. The research attempts to establish whether trade liberalization and macroeconomic reforms played a decisive role in stimulating the export boom or whether changes in the global flower market created Ecuador’s comparative advantage in flower exports independent of the policy regime. The article concludes that both sets of forces played an important role., Submitted by Chris Lewis (clewis@american.edu) on 2009-02-18T14:59:23Z No. of bitstreams: 1 2004-13.pdf: 267920 bytes, checksum: 91a44a45a74593abc52c78ccc204299c (MD5), Made available in DSpace on 2009-02-18T14:59:24Z (GMT). No. of bitstreams: 1 2004-13.pdf: 267920 bytes, checksum: 91a44a45a74593abc52c78ccc204299c (MD5) Previous issue date: 2004-11, Department of Economics, American University
Rush to judgment: the STI-treatment trials and HIV in sub-Saharan Africa
Stillwaggon E and Sawers L. Journal of the International AIDS Society 2015, 18:19844 http://www.jiasociety.org/index.php/jias/article/view/19844 | http://dx.doi.org/10.7448/IAS.18.1.19844, Introduction: 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. Discussion: Examination of the trials reveals critical methodological problems sufficient to account for statistically insignificant outcomes in nine of the ten trials. Shortcomings of the trials include weak exposure contrast, confounding, non-differential misclassification, contamination and effect modification, all of which consistently bias the results toward the null. In any future STI-HIV trial, ethical considerations will again require weak exposure contrast. The complexity posed by HIV transmission in the genital microbial environment means that any future STI-HIV trial will face confounding, non-differential misclassification and effect modification. As a result, it is unlikely that additional trials would be able to answer the question of whether STI control reduces HIV incidence. Conclusions: Shortcomings in published RCTs render invalid the conclusion that treating STIs and other cofactor infections is ineffective in HIV prevention. Meta-analyses of observational studies conclude that STIs can raise HIV transmission efficiency two- to fourfold. Health policy is always implemented under uncertainty. Given the known benefits of STI control, the irreparable harm from not treating STIs and the likely decline in HIV incidence resulting from STI control, it is appropriate to expand STI control programmes and to use funds earmarked for HIV prevention to finance those programmes.
Sustainable Floriculture in Ecuador
Working Paper No. 2005-03. 10 pages., This article explores the causes and consequences of the export boom in fresh cut flowers from Ecuador. Between the 1980s and the present, flower exports rose from almost nothing to 9 percent of the country=s nonpetroleum export earnings. This research asks whether flower exports can continue to expand. It also examines the economic, social, and cultural impact of the flower boom on the regions of Ecuador where the flowers are cultivated. Finally, the article discusses the environmental impact of floriculture on workers in the industy., Submitted by Chris Lewis (clewis@american.edu) on 2009-02-18T16:20:29Z No. of bitstreams: 1 2005-03.pdf: 110627 bytes, checksum: 45e7f4afe33d935329460ef0b247a092 (MD5), Made available in DSpace on 2009-02-18T16:20:29Z (GMT). No. of bitstreams: 1 2005-03.pdf: 110627 bytes, checksum: 45e7f4afe33d935329460ef0b247a092 (MD5) Previous issue date: 2005-03, Department of Economics, American University
Understanding the Southern African ‘Anomaly’ Poverty, Endemic Disease, and HIV
Working Paper No. 2008-11. 17 pages., Background: Adult HIV prevalence in the nine countries of southern Africa averages more than 16 times the prevalence in other low- and middle-income countries. Previous studies argue that the intensity of the HIV epidemic in southern Africa results from regional characteristics, such as apartheid labor regulations and regional mineral wealth, which contributed to circular migration patterns and highly skewed income distribution. The present study also emphasizes the importance of cofactor diseases, which are suspected of raising HIV prevalence by increasing HIV viral load in infected persons or by making uninfected persons more vulnerable to HIV infection through lower immunity or genital lesions and/or inflammation. Method: the study uses multiple regression analysis on country-level data with HIV prevalence as the dependent variable. Regressors are ten socio-economic variables used in most previous cross-national analyses of HIV, two measures of cross-border migration, and measures of six cofactor infections. Results: The 10 socio-economic variables “explain” statistically only 25% of the difference in HIV prevalence between southern Africa and other low- and middle-income countries, but adding the four cofactor infection variables to the model allows us to “explain” 80% of the southern Africa difference in HIV prevalence. Conclusion: The relative affluence of southern Africa and historical migration patterns have tended to mask the vulnerability of the majority of the population who are poor and who have very high prevalence of infectious and parasitic diseases. Those diseases replicate a cycle of poverty that can lead not just to social vulnerability to HIV through risky behaviors but also to biological vulnerability through coinfections. An important implication of this research is that integrating treatment of endemic diseases with other HIVprevention policies may be necessary to slow the spread of HIV. Treatment of cofactor infections is a lowcost, policy-sensitive, high-impact variable., Submitted by Chris Lewis (clewis@american.edu) on 2009-02-26T14:21:17Z No. of bitstreams: 1 2008-11.pdf: 180205 bytes, checksum: d8f4248791ada5780c22c88a93bfa9fe (MD5), Made available in DSpace on 2009-02-26T14:21:17Z (GMT). No. of bitstreams: 1 2008-11.pdf: 180205 bytes, checksum: d8f4248791ada5780c22c88a93bfa9fe (MD5) Previous issue date: 2008-07, Department of Economics, American University; Gettysburg College