Publications Directory

Publications Directory

New performance metrics for quantitative PCR microbial source tracking methods
Dan Wang, Hyatt Green, Orin Shanks, Ali Boehm

The ability to select the best quantitative microbial source tracking method for a particular application is paramount. The typical approach is to look at the sensitivity and specificity. This article points out shortcomings in this approach for qPCR microbial source tracking methods and introduces alternative metrics that can improve the evaluation of these methods. The takeaway message is that there are two additional factors to consider when evaluating assay performance: 1) look at the standard deviation of concentration on the standard curve, and 2) test a reference fecal pollution source at a single high DNA concentration.

Water, Sanitation and Health North America Friday, August 16, 2013 Visit Website
Cluster-randomised controlled trials of individual and combined water, sanitation, hygiene and nutritional interventions in rural Bangladesh and Kenya: the WASH Benefits study design and rationale
Benjamin F Arnold, Clair Null, Stephen Luby, Leanne Unicom, Christine P Stewart, Kathryn G Dewey, Tahmeed Ahmed, Sania Ashraf, Garret Christensen, Thomas Clasen, Holly N Dentz, Lia C H Fernald, Rashidul Haque, Alan E Hubbard, Patricia Kariger, Elli Leontsini, Audrie Lin, Sammy M Njenga, Amy Pickering, Pavani K. Ram, Fahmida Tofail, Peter J Winch, John M Colford Jr

Enteric infections are common during the first years of life in low-income countries and contribute to growth faltering with long-term impairment of health and development. Water quality, sanitation, handwashing and nutritional interventions can independently reduce enteric infections and growth faltering. There is little evidence that directly compares the effects of these individual and combined interventions on diarrhoea and growth when delivered to infants and young children. The objective of the WASH Benefits study is to help fill this knowledge gap.

Water, Sanitation and Health Sub-Saharan Africa Thursday, August 1, 2013 Visit Website
Household Environmental Conditions Are Associated with Enteropathy and Impaired Growth in Rural Bangladesh
Audrie Lin, Benjamin F Arnold, Sadia Afreen, Rie Goto, Tarique Mohammad Nurul Huda, Rashidul Haque, Rubhana Raqib, Leanne Unicomb, Tahmeed Ahmed, John M Colford Jr, Stephen Luby

Environmental enteropathy is a disorder featuring a small bowel with abnormal morphology and physiology. In more general terms, environmental enteropathy causes constant gastrointestinal distress, even when a person is not ill. In children, it is often related to undernutrition and stunted growth. This study shows that there may be hope for preventing environmental enteropathy in children by demonstrating the association between household environmental conditions and enteropathy and impaired growth. In practice, this means that water, sanitation, and hygiene interventions can help prevent chronic health issues in developing countries.

Water, Sanitation and Health South Asia Wednesday, July 10, 2013 Visit Website
Access to Waterless Hand Sanitizer Improves Student Hand Hygiene Behavior in Primary Schools in Nairobi, Kenya
Amy Pickering, Jenna Davis, Annalise Blum, Jenna Scalmanini, Beryl Oyier, George Okoth, Robert F. Breiman, Pavani K. Ram

Handwashing is difficult in settings with limited resources and water access. In primary schools within urban Kibera, Kenya, we investigated the impact of providing waterless hand sanitizer on student hand hygiene behavior. The results showed that providing waterless hand sanitizer markedly increased student hand cleaning after toilet use, whereas the soap intervention did not. Waterless hand sanitizer may be a promising option to improve student hand cleansing behavior, particularly in schools with limited water access.

Expanding Access Sub-Saharan Africa Monday, July 8, 2013 Visit Website
The use of satellite data for crop yield gap analysis

A review paper on how satellites can be used to understand productivity in agricultural regions, particularly irrigated regions.

WASH and Development, Sustainable Service Models Other Friday, March 1, 2013 Visit Website
Sunlight inactivation of human viruses and bacteriophages in coastal waters containing natural photosensitizers
Andrea I. Silverman, Britt M. Peterson, Ali Boehm, Kristopher McNeill

Sunlight inactivation of poliovirus type 3 (PV3), adenovirus type 2 (HAdV2), and two bacteriophage (MS2 and PRD1) was investigated in an array of coastal waters to better understand solar inactivation mechanisms and the effect of natural water constituents on observed inactivation rates (kobs). Results illustrate that differences in water composition can shift absolute and relative inactivation rates of viruses, which has important implications for natural wastewater treatment systems, solar disinfection (SODIS), and the use of indicator organisms for monitoring water quality.

Water, Sanitation and Health Other Tuesday, February 5, 2013 Visit Website
Satellite detection of earlier wheat sowing in India and implications for yield trends
David Lobell, J. Ivan Ortiz-Monasterio, Adam M. Sibley, V.S. Sohu

An analysis of recent trends in sowing times in India, showing that wheat has become sown significantly earlier in the past decade, and that this can explain roughly all of the yield increase since 2000.

WASH and Development, Sustainable Service Models South Asia Friday, February 1, 2013 Visit Website
Hands and Water as Vectors of Diarrheal Pathogens in Bagamoyo, Tanzania

Using molecular methods, this study examines the relative importance of different exposure routes by measuring enteric bacteria (pathogenic Escherichia coli) and viruses (rotavirus, enterovirus, adenovirus) in hand rinses, stored water, and source waters in Bagamoyo, Tanzania.

Water, Sanitation and Health Sub-Saharan Africa Monday, November 26, 2012 Visit Website
The impact of urbanization on water vulnerability: A coupled human-environment system approach for Chennai, India
Veena Srinivasana, Karen C. Setob, Ruth Emerson, Steve Gorelick

This paper examines the relationship between urbanization and water vulnerability for a fast-growing city, Chennai, India, using a coupled human–environment systems (CHES) modeling approach. The result of the study suggest that in order to reduce vulnerability to water shortages, there is a need for new forms of urban governance and planning institutions that are capable of managing both centralized actions by utilities and decentralized actions by millions of households.

Sustainable Service Models South Asia Thursday, November 15, 2012 Visit Website
Scenarios of transmission risk of foot-and-mouth with climatic, social and landscape changes in southern Africa
Elise Diona, Eric Lambin

Part of southern Africa is endemic to foot-and-mouth disease. African buffaloes (Syncerus caffer) living in the Kruger National Park act as virus reservoirs and spread the infection to domestic cattle by close contacts. This study explores potential factors influencing the spatial and temporal risk of disease transmission, based on a spatially-explicit multi-agent simulation that represents the dynamics of buffalo-cattle contacts. The knowledge gained through model simulation experiments is useful to prevent disease transmission and improve the management of disease risk.

Water, Sanitation and Health Sub-Saharan Africa Thursday, November 1, 2012 Visit Website
The nature and causes of the global water crisis: Syndromes from a meta-analysis of coupled human-water studies
V. Srinivasan, Eric Lambin, Steve Gorelick, B. H. Thompson, S. Rozelle

Freshwater scarcity has been cited as the major crisis of the 21st century, but it is surprisingly hard to describe the nature of the global water crisis. This study conducted a meta-analysis of 22 coupled human–water system case studies, using qualitative comparison analysis (QCA) to identify water resource system outcomes and the factors that drive them.

Expanding Access Other Friday, October 5, 2012 Visit Website
Mechanisms for Photoinactivation of Enterococcus faecalis in Seawater
Lauren M. Sassoubre, Kara L. Nelson, Ali Boehm

We investigated sunlight inactivation of Enterococcus faecalis to gain insight into photoinactivation mechanisms and cellular responses to photostress. E. faecalis bacteria were exposed to natural sunlight in clear, filtered seawater under both oxic and anoxic conditions to test the relative importance of oxygen-mediated and non-oxygen-mediated photoinactivation mechanisms. Photoinactivation, based on numbers of cultivable cells, was faster in oxic than in anoxic microcosms exposed to sunlight, suggesting that oxygen-mediated photoinactivation dominated. This research furthers our understanding of photoinactivation mechanisms and the conditions under which diel fluctuations in enterococci can be expected in natural and engineered systems.

Water, Sanitation and Health Other Friday, August 31, 2012 Visit Website
Fecal contamination and diarrheal pathogens on surfaces and in soils among Tanzanian households with and without improved sanitation
Amy Pickering, T. Julian, S. Marks, Mia Catharine Mattioli, Ali Boehm, K. Schwab, Jenna Davis

Little is known about the extent or pattern of environmental fecal contamination among households using low-cost, on-site sanitation facilities, or what role environmental contamination plays in the transmission of diarrheal disease. A microbial survey...

WASH and Development Sub-Saharan Africa Tuesday, June 5, 2012 Visit Website
Salt marsh ecohydrological zonation due to heterogeneous vegetation-groundwater-surface water interactions
Kevan B. Moffett, Steve Gorelick, Robert G. McLaren, Edward A. Sudicky

Vegetation zonation and tidal hydrology are basic attributes of intertidal salt marshes, but specific links among vegetation zonation, plant water use, and spatiotemporally dynamic hydrology have eluded thorough characterization. This study developed a quantitative model of an intensively studied salt marsh field site, integrating coupled 2-D surface water and 3-D groundwater flow and zonal plant water use.

WASH and Development Other Wednesday, February 15, 2012 Visit Website
Freshwater Availability and Water Fetching Distance Affect Child Health in Sub-Saharan Africa

A 15-min decrease in one-way walk time to water source is associated with a 41% average relative reduction in diarrhea prevalence, improved anthropometric indicators of child nutritional status, and a 11% relative reduction in under-five child mortality. These results suggest that reducing the time cost of fetching water should be a priority for water infrastructure investments in Africa.

Expanding Access Sub-Saharan Africa Thursday, February 9, 2012 Visit Website