Andrea is interested in the eco-epidemiology of infectious diseases and how social factors interact with environmental drivers of transmission. Her dissertation research focuses on the human-environment dynamics involved in the transmission of schistosomiasis in the Senegal River Basin. Previously, Andrea has led field work on the ecology of West Nile virus transmission in urban Atlanta as well as on the role of social factors in explaining environmental risk for cholera in the Dominican Republic. Andrea holds a master’s of public health in global epidemiology from Emory University’s Rollins School of Public Health and a bachelor of arts in biology and Spanish from the University of Minnesota, Morris.
Honors & Awards
Stanford Interdisciplinary Graduate Fellowship, Vice Provost for Graduate Education (2017-2020)
Doctor of Philosophy, Stanford University, ENVRES-PHD (2020)
Master of Public Health, Emory University, Global Epidemiology (2013)
Bachelor of Arts, University of Minnesota Morris, Biology and Spanish (2011)
BA, University of Minnesota, Morris, Biology and Spanish
MPH, Rollins School of Public Health, Emory University, Global Epidemiology
Giulio De Leo, Postdoctoral Faculty Sponsor
Current Research and Scholarly Interests
Andrea's research interests are in the ecology and epidemiology of infectious disease. Her work focuses particularly on the social and environmental determinants of schistosomiasis, a parasitic disease that infects humans through direct contact with freshwater.
Precision mapping of snail habitat provides a powerful indicator of human schistosomiasis transmission.
Proceedings of the National Academy of Sciences of the United States of America
Recently, the World Health Organization recognized that efforts to interrupt schistosomiasis transmission through mass drug administration have been ineffective in some regions; one of their new recommended strategies for global schistosomiasis control emphasizes targeting the freshwater snails that transmit schistosome parasites. We sought to identify robust indicators that would enable precision targeting of these snails. At the site of the world's largest recorded schistosomiasis epidemic-the Lower Senegal River Basin in Senegal-intensive sampling revealed positive relationships between intermediate host snails (abundance, density, and prevalence) and human urogenital schistosomiasis reinfection (prevalence and intensity in schoolchildren after drug administration). However, we also found that snail distributions were so patchy in space and time that obtaining useful data required effort that exceeds what is feasible in standard monitoring and control campaigns. Instead, we identified several environmental proxies that were more effective than snail variables for predicting human infection: the area covered by suitable snail habitat (i.e., floating, nonemergent vegetation), the percent cover by suitable snail habitat, and size of the water contact area. Unlike snail surveys, which require hundreds of person-hours per site to conduct, habitat coverage and site area can be quickly estimated with drone or satellite imagery. This, in turn, makes possible large-scale, high-resolution estimation of human urogenital schistosomiasis risk to support targeting of both mass drug administration and snail control efforts.
View details for DOI 10.1073/pnas.1903698116
View details for PubMedID 31659025
Unavoidable Risks: Local Perspectives on Water Contact Behavior and Implications for Schistosomiasis Control in an Agricultural Region of Northern Senegal.
The American journal of tropical medicine and hygiene
Human schistosomiasis is a snail-borne parasitic disease affecting more than 200 million people worldwide. Direct contact with snail-infested freshwater is the primary route of exposure. Water management infrastructure, including dams and irrigation schemes, expands snail habitat, increasing the risk across the landscape. The Diama Dam, built on the lower basin of the Senegal River to prevent saltwater intrusion and promote year-round agriculture in the drought-prone Sahel, is a paradigmatic case. Since dam completion in 1986, the rural population-whose livelihoods rely mostly on agriculture-has suffered high rates of schistosome infection. The region remains one of the most hyperendemic regions in the world. Because of the convergence between livelihoods and environmental conditions favorable to transmission, schistosomiasis is considered an illustrative case of a disease-driven poverty trap (DDPT). The literature to date on the topic, however, remains largely theoretical. With qualitative data generated from 12 focus groups in four villages, we conducted team-based theme analysis to investigate how perception of schistosomiasis risk and reported preventive behaviors may suggest the presence of a DDPT. Our analysis reveals three key findings: 1) rural villagers understand schistosomiasis risk (i.e., where and when infections occur), 2) accordingly, they adopt some preventive behaviors, but ultimately, 3) exposure persists, because of circumstances characteristic of rural livelihoods. These findings highlight the capacity of local populations to participate actively in schistosomiasis control programs and the limitations of widespread drug treatment campaigns. Interventions that target the environmental reservoir of disease may provide opportunities to reduce exposure while maintaining resource-dependent livelihoods.
View details for DOI 10.4269/ajtmh.19-0099
View details for PubMedID 31452497
- Modelled effects of prawn aquaculture on poverty alleviation and schistosomiasis control NATURE SUSTAINABILITY 2019; 2 (7): 611–20
- Ecological control of schistosomiasis in Sub-Saharan Africa: restoration of predator-prey dynamics to reduce transmission ECOLOGY AND EVOLUTION OF INFECTIOUS DISEASES: PATHOGEN CONTROL AND PUBLIC HEALTH MANAGEMENT IN LOW-INCOME COUNTRIES 2018: 236–51
Nearly 400 million people are at higher risk of schistosomiasis because dams block the migration of snail-eating river prawns
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
2017; 372 (1722)
Dams have long been associated with elevated burdens of human schistosomiasis, but how dams increase disease is not always clear, in part because dams have many ecological and socio-economic effects. A recent hypothesis argues that dams block reproduction of the migratory river prawns that eat the snail hosts of schistosomiasis. In the Senegal River Basin, there is evidence that prawn populations declined and schistosomiasis increased after completion of the Diama Dam. Restoring prawns to a water-access site upstream of the dam reduced snail density and reinfection rates in people. However, whether a similar cascade of effects (from dams to prawns to snails to human schistosomiasis) occurs elsewhere is unknown. Here, we examine large dams worldwide and identify where their catchments intersect with endemic schistosomiasis and the historical habitat ranges of large, migratory Macrobrachium spp. prawns. River prawn habitats are widespread, and we estimate that 277-385 million people live within schistosomiasis-endemic regions where river prawns are or were present (out of the 800 million people who are at risk of schistosomiasis). Using a published repository of schistosomiasis studies in sub-Saharan Africa, we compared infection before and after the construction of 14 large dams for people living in: (i) upstream catchments within historical habitats of native prawns, (ii) comparable undammed watersheds, and (iii) dammed catchments beyond the historical reach of migratory prawns. Damming was followed by greater increases in schistosomiasis within prawn habitats than outside prawn habitats. We estimate that one third to one half of the global population-at-risk of schistosomiasis could benefit from restoration of native prawns. Because dams block prawn migrations, our results suggest that prawn extirpation contributes to the sharp increase of schistosomiasis after damming, and points to prawn restoration as an ecological solution for reducing human disease.This article is part of the themed issue 'Conservation, biodiversity and infectious disease: scientific evidence and policy implications'.
View details for DOI 10.1098/rstb.2016.0127
View details for Web of Science ID 000399956400008
View details for PubMedID 28438916
Cholera control and anti-Haitian stigma in the Dominican Republic: from migration policy to lived experience.
Anthropology & medicine
As cholera spread from Haiti to the Dominican Republic, Haitian migrants, a largely undocumented and stigmatized population in Dominican society, became a focus of public health concern. Concurrent to the epidemic, the Dominican legislature enacted new documentation requirements. This paper presents findings from an ethnographic study of anti-Haitian stigma in the Dominican Republic from June to August 2012. Eight focus group discussions (FGDs) were held with Haitian and Dominican community members. Five in-depth interviews were held with key informants in the migration policy sector. Theoretical frameworks of stigma's moral experience guided the analysis of how cholera was perceived, ways in which blame was assigned and felt and the relationship between documentation and healthcare access. In FGDs, both Haitians and Dominicans expressed fear of cholera and underscored the importance of public health messages to prevent the epidemic's spread. However, health messages also figured into experiences of stigma and rationales for blame. For Dominicans, failure to follow public health advice justified the blame of Haitians and seemed to confirm anti-Haitian sentiments. Haitians communicated a sense of powerlessness to follow public health messages given structural constraints like lack of safe water and sanitation, difficulty accessing healthcare and lack of documentation. In effect, by making documentation more difficult to obtain, the migration policy undermined cholera programs and contributed to ongoing processes of moral disqualification. Efforts to eliminate cholera from the island should consider how policy and stigma can undermine public health campaigns and further jeopardize the everyday 'being-in-the-world' of vulnerable groups.
View details for DOI 10.1080/13648470.2017.1368829
View details for PubMedID 29058456
Prevalence of cholera risk factors between migrant Haitians and Dominicans in the Dominican Republic.
Revista panamericana de salud publica = Pan American journal of public health
2015; 37 (3): 125–32
To determine whether cholera risk factor prevalence in the Dominican Republic can be explained by nationality, independent of other factors, given the vulnerability of many Haitians in the country and the need for targeted prevention.A cross-sectional, observational household survey (103 Haitian and 260 Dominican) was completed in 18 communities in July 2012. The survey included modules for demographics, knowledge, socioeconomic status, and access to adequate water, sanitation, and hygiene (WASH) infrastructure. Logistic regression assessed differential access to WASH infrastructure and Poisson regression assessed differences in cholera knowledge, controlling for potential confounders.Dominican and Haitian households differed on demographic characteristics. Haitians had lower educational attainment, socioeconomic status, and less knowledge of cholera than Dominicans (adjusted odds ratio [aOR] = 0.66; 95% confidence interval [95%CI] = 0.55-0.81). Access to improved drinking water was low for both groups, but particularly low among rural Haitians (aOR = 0.21; 95%CI: 0.04-1.01). No differences were found in access to sanitation after adjusting for sociodemographic confounders (aOR = 1.00; 95%CI: 0.57-1.76).Urban/rural geography and socioeconomic status play a larger role in cholera risk factor prevalence than nationality, indicating that Haitians' perceived vulnerability to cholera is confounded by contextual factors. Understanding the social dynamics that lead to cholera risk can inform control strategies, leading to better targeting and the possibility of eliminating cholera from the island.
View details for PubMedID 25988248
Long term impacts of combined sewer overflow remediation on water quality and population dynamics of Culex quinquefasciatus, the main urban West Nile virus vector in Atlanta, GA.
2014; 129: 20–26
Combined sewers are a significant source of urban water pollution due to periodic discharges into natural streams. Such events (called combined sewer overflows, or CSOs) contribute to the impairment of natural waterways and are associated with increased mosquito productivity and elevated risk of West Nile virus transmission.We investigated the impact of CSOs on water quality and immature mosquito productivity in the city of Atlanta, Georgia, one year before and four years after CSO facility remediation.Water quality (ammonia, phosphate, nitrate and dissolved oxygen concentrations), immature mosquitoes (larvae and pupae), water temperature and rainfall were quantified biweekly between June-October at two urban creeks during 2008-2012. A before-after control-intervention design tested the impact of remediation on mosquito productivity and water quality, whereas generalized linear mixed-effect models quantified the factors explaining the long term impacts of remediation on mosquito productivity.Ammonia and phosphate concentrations and late immature (fourth-instar and pupae) mosquito populations were significantly higher in CSO than in non-CSO creeks, while dissolved oxygen concentrations were lower. Remediation significantly improved water quality estimates (particularly ammonia and dissolved oxygen) and reduced the number of overflows, mosquito productivity and the overall contribution of CSO-affected streams as sources of vectors of West Nile virus.The quality of water in CSOs provided a suitable habitat for immature mosquitoes. Remediation of the CSO facility through the construction of a deep storage tunnel improved water quality indices and reduced the productivity of mosquito species that can serve as vectors of West Nile virus.
View details for DOI 10.1016/j.envres.2013.12.008
View details for PubMedID 24528998
Ethnic differences in predictors of HPV vaccination: comparisons of predictors for Latina and non-Latina White women.
Journal of sex research
2013; 50 (8): 748–56
The purpose of this study was to examine how social and behavioral factors such as age of first intercourse, mother-daughter communication, and perceived norms are associated with human papillomavirus (HPV) vaccination behaviors, and whether ethnicity moderates those associations (non-Latina White versus Latina participants). From June through December 2009, we surveyed a community sample of 309 White and Latina women, ages 15 to 30. We recruited participants from local health care clinics in Des Moines, Iowa. Vaccination status was not significantly different for Whites versus Latinas. The effects of age at first intercourse, mother-daughter communication about values related to sex, and descriptive norms of HPV vaccine uptake were all significantly moderated by ethnicity. The current findings reveal that sociocultural and behavioral factors that affect HPV vaccine uptake do not affect White and Latina women in the same fashion. In the future, public health campaigns about HPV and the HPV vaccine may be more effective if their messages are sensitive to these differences.
View details for DOI 10.1080/00224499.2012.692406
View details for PubMedID 23030843