Publications Directory

Publications Directory

Genotypic and phenotypic characterization of Escherichia coli isolated from feces, hands, and soils in rural Bangladesh using the Colilert Quanti-Tray System (IDEXX)
Timothy R. Julian, M. Aminul Islam, Amy Pickering, Subarna Roy, Erica R. Fuhrmeister, Ayse Ercumen, Angela Harris, Jason Bishai, Kellogg J. Schwab

The increased awareness of the role of environmental matrices in enteric disease transmission has resulted in the need for rapid, field-based methods for fecal indicator bacteria and pathogen detection. We found that Colilert, and likely other β-glucuronidase-based assays, is appropriate for detection of E. coli on hands and in soils with low false-positive rates. Also, E. coli isolated from hands and soils in Bangladeshi households are diverse and indistinguishable from cattle, chicken, and human fecal isolates, using traditional biochemical assays and phylogrouping.

Water, Sanitation and Health South Asia Sunday, March 1, 2015 Visit Website
Hand-to-mouth contacts result in greater ingestion of feces than dietary water consumption in Tanzania: A quantitative fecal exposure assessment model
Mia Catharine Mattioli, Jenna Davis, Ali Boehm

This research evaluated the relative contribution of two important environmental transmission routes of diarrhea-causing pathogens to young children in low-income countries-hands and water. A Monte Carlo simulation was used to model the amount of human feces ingested by children under five years old from exposure via hand-to-mouth contacts and stored drinking water ingestion in Bagamoyo, Tanzania. The model results show that Tanzanian children ingest a significantly greater amount of feces each day from hand-to-mouth contacts than from drinking water, which may help elucidate why interventions focused on water without also addressing hygiene often see little to no effect on reported incidence of diarrhea.

Water, Sanitation and Health Sub-Saharan Africa Monday, January 5, 2015 Visit Website
Video Surveillance Captures Student Hand Hygiene Behavior, Reactivity to Observation, and Peer Influence in Kenyan Primary Schools
Amy Pickering, Annalise Blum, Robert F. Breiman, Pavani K. Ram, Jenna Davis

Student hand cleaning behavior was monitored with video surveillance and in-person structured observation, both simultaneously and separately, at four primary schools in urban Kenya over a study period of 8 weeks. Video surveillance of hand hygiene behavior yields results comparable to in-person observation among schools in a resource-constrained setting and has certain advantages over in-person observation, including rapid data processing and the capability to capture new behavioral insights. The results showed that peer influence can significantly improve student hand cleaning behavior and, when possible, should be exploited in the design and implementation of school hand hygiene programs.

Water, Sanitation and Health Sub-Saharan Africa Thursday, March 27, 2014 Visit Website
Enteric Pathogens in Stored Drinking Water and on Caregiver’s Hands in Tanzanian Households with and without Reported Cases of Child Diarrhea
Mia Catharine Mattioli, Ali Boehm, Jenna Davis, Angela Harris, Amy Pickering

The presence of molecular markers for three enteric viruses (enterovirus, adenovirus, and rotavirus), seven Escherichia coli virulence genes, and human-specific Bacteroidales was assessed in hand rinses and household stored drinking water of Tanzanian households with and without cases of childhood diarrhea. Surprisingly, better stored water quality was found among households with diarrhea, indicating that caregivers with sick children may be more likely to ensure safe drinking water in the home. The analysis also showed that interventions to increase the quantity of water available for hand washing, and to improve food hygiene, may reduce exposure to enteric pathogens in the domestic environment.

Water, Sanitation and Health Sub-Saharan Africa Thursday, January 2, 2014 Visit Website
Performance of human fecal anaerobe-associated PCR-based assays in a multi-laboratory method evaluation study
Blythe A. Layton, Yiping Cao, Darcy L. Ebentier, Kaitlyn Hanley, Elisenda Ballesté, João Brandão, Muruleedhara Byappanahalli, Reagan Converse, Andreas H. Farnleitner, Jennifer Gentry-Shields, Maribeth L. Gidley, Michèle Gourmelon, Chang Soo Lee, Jiyoung Lee, Solen Lozach, Tania Madi, Wim G. Meijer, Rachel Noble, Lindsay Peed, Georg H. Reischer, Raquel Rodrigues, Joan B. Rose, Alexander Schriewer, Chris Sinigalliano, Sangeetha Srinivasan, Jill Stewart, Laurie C. Van De Werfhorst, Dan Wang, Richard Whitman, Stefan Wuertz, Jenny Jay, Patricia A. Holden, Ali Boehm, Orin Shanks

Is stool, septage, and sewage all the same in regards to microbial source tracking? This is another paper resulting from the Source Identification Protocol Project (SIPP). It looks specifically at performance of human fecal-associated PCR-based assays and dives into three important issues. First, they discuss the impact of detectable but not quantifiable samples on assay performance. Second, they look at performance for all filter sample units of measure. Third, they determine how the source of the sample (stool, septage, sewage) influences performance.

Water, Sanitation and Health North America Friday, November 15, 2013 Visit Website
Performance of Viruses and Bacteriophages for Fecal Source Determination in a Multi-Laboratory, Comparative Study
Valerie J. Harwood, Ali Boehm, Lauren M. Sassoubre, Kannappan Vijayavel, Jill R. Stewart, Theng-Theng Fong, Marie-Paule Caprais, Reagan R. Converse, David Diston, James Ebdon, Jed A. Fuhrman, Michele Gourmelon, Jennifer Gentry-Shields, John F. Griffith, Donna R. Kashian, Rachel T. Noble, Huw Taylor, Melanie Wicki

Interested in microbial source tracking? This study constitutes the largest multi-laboratory study on microbial source tracking (MST) to date. The Source Identification Protocol Project (SIPP) covers a wide range of MST methods; this paper looks specifically at virus and bacteriophage methods targeting human fecal or sewage contamination. The advantages of using viruses for MST are that they may provide a more accurate measure of gastrointestinal illness risk and non-pathogenic viruses exhibit similar fate and transport to viral pathogens in the environment. Additionally, viruses are highly host-specific, which improves confidence in identification of pollution sources.

Water, Sanitation and Health North America Friday, November 15, 2013 Visit Website
The challenge of global water access monitoring: evaluating straight-line distance versus self-reported travel time among rural households in Mozambique
Jeff Ho, Kory Russel, Jenna Davis

"Access to improved water supply“ is currently monitored globally without consideration of time and/or distance considerations despite almost half of the world's population leaving their home to fetch water. And although support is growing for the incorporation of fetching time and/or distance considerations into global monitoring, current efforts typically rely on self-reported distance and/or travel time data that have been shown to be unreliable. To aid in developing policy, this study provides a head-to-head comparison of such indicators with other possible distance/time metrics, finding that the share of households classified as having versus lacking access would differ by more than 70 percentage points depending on the particular indicator employed.

Water, Sanitation and Health, Expanding Access Sub-Saharan Africa Friday, September 13, 2013 Visit Website
Mechanisms of post-supply contamination of drinking water in Bagamoyo, Tanzania
Angela Harris, Jenna Davis, Ali Boehm

In Tanzania we found that the microbiological quality of households' stored drinking water varies significantly over the course of the day. We tested for fecal indicator bacteria in the water during its collection at the source, while being stored in the home, and following any extraction from the storage container. Levels of contamination increased after filling the storage container, as well as after stored water was extracted, even when using strategies considered to be relatively safe. As in-home water storage is likely to be the norm for millions of households in the foreseeable future, additional efforts are needed to prevent contamination from storage containers and during extraction.

Water, Sanitation and Health Sub-Saharan Africa Sunday, September 1, 2013 Visit Website
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