Amy Pickering, PhD, is a Fellow in the Center for Innovation in Global Health and a Research Scientist in the Woods Institute for the Environment at Stanford University. Her previous and current research combines tools from multiple disciplines to study the sustainability and child health impacts of water, hygiene, and sanitation interventions in low-income settings. Dr. Pickering's academic career has its foundation in Biological and Environmental engineering (B.S. Cornell University, M.S. UC Berkeley), with doctoral training in Stanford University’s Interdisciplinary Program in Environment and Resources. Dr. Pickering uses tools from epidemiology, microbiology, and social science to understand enteric disease transmission pathways among households in low-income countries and develop low-cost and scalable interventions to interrupt them. She has over 10 years of experience conducting environmental health research in low-resource settings, and have led studies in both urban and rural sites in Kenya, Bangladesh, Mali, India, and Tanzania. She is currently leading the measurement of parasite infections, including soil-transmitted helminth infections, among children enrolled in a large-scale (>8000 children enrolled) randomized controlled trial in rural Kenya to evaluate the effect of improved sanitation, water, hygiene, and nutrition on early child growth and development.

Current Role at Stanford

Fellow, Center for Innovation in Global Health
Research Engineer, Water, Health, and Development Program, Woods Institute for the Environment

Institute Affiliations

2013-14 Courses

Professional Affiliations and Activities

  • Associate Fellow, Stanford Center for Innovation in Global Health (2015 - Present)

All Publications

  • Soil-Transmitted Helminth Eggs Are Present in Soil at Multiple Locations within Households in Rural Kenya PLOS ONE Steinbaum, L., Njenga, S. M., Kihara, J., Boehm, A. B., Davis, J., Null, C., Pickering, A. J. 2016; 11 (6)


    Almost one-quarter of the world's population is infected with soil-transmitted helminths (STH). We conducted a study to determine the prevalence and location of STH-Ascaris, Trichuris, and hookworm spp.-egg contamination in soil within rural household plots in Kenya. Field staff collected soil samples from July to September 2014 from the house entrance and the latrine entrance of households in Kakamega County; additional spatial sampling was conducted at a subset of households (N = 22 samples from 3 households). We analyzed soil samples using a modified version of the US Environmental Protection Agency (EPA) method for enumerating Ascaris in biosolids. We found 26.8% of households had one or more species of STH eggs present in the soil in at least one household location (n = 18 out of 67 households), and Ascaris was the most commonly detected STH (19.4%, n = 13 out of 67 households). Prevalence of STH eggs in soil was equally likely at the house entrance (19.4%, N = 67) as at the latrine entrance (11.3%, N = 62) (p = 0.41). We also detected STH eggs at bathing and food preparation areas in the three houses revisited for additional spatial sampling, indicating STH exposure can occur at multiple sites within a household plot, not just near the latrine. The highest concentration of eggs in one house occurred in the child's play area. Our findings suggest interventions to limit child exposure to household soil could complement other STH control strategies.

    View details for DOI 10.1371/journal.pone.0157780

    View details for Web of Science ID 000378393600017

    View details for PubMedID 27341102

  • Handwashing With a Water-Efficient Tap and Low-Cost Foaming Soap: The Povu Poa "Cool Foam" System in Kenya. Global health, science and practice Whinnery, J., Penakalapati, G., Steinacher, R., Wilson, N., Null, C., Pickering, A. J. 2016; 4 (2): 336-341

    View details for DOI 10.9745/GHSP-D-16-00022

    View details for PubMedID 27353625

  • Hand- and Object-Mouthing of Rural Bangladeshi Children 3-18 Months Old INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH Kwong, L. H., Ercumen, A., Pickering, A. J., Unicomb, L., Davis, J., Luby, S. P. 2016; 13 (6)


    Children are exposed to environmental contaminants by placing contaminated hands or objects in their mouths. We quantified hand- and object-mouthing frequencies of Bangladeshi children and determined if they differ from those of U.S. children to evaluate the appropriateness of applying U.S. exposure models in other socio-cultural contexts. We conducted a five-hour structured observation of the mouthing behaviors of 148 rural Bangladeshi children aged 3-18 months. We modeled mouthing frequencies using 2-parameter Weibull distributions to compare the modeled medians with those of U.S. children. In Bangladesh the median frequency of hand-mouthing was 37.3 contacts/h for children 3-6 months old, 34.4 contacts/h for children 6-12 months old, and 29.7 contacts/h for children 12-18 months old. The median frequency of object-mouthing was 23.1 contacts/h for children 3-6 months old, 29.6 contacts/h for children 6-12 months old, and 15.2 contacts/h for children 12-18 months old. At all ages both hand- and object-mouthing frequencies were higher than those of U.S. children. Mouthing frequencies were not associated with child location (indoor/outdoor). Using hand- and object-mouthing exposure models from U.S. and other high-income countries might not accurately estimate children's exposure to environmental contaminants via mouthing in low- and middle-income countries.

    View details for DOI 10.3390/ijerph13060563

    View details for Web of Science ID 000378860100042

    View details for PubMedID 27271651

  • Ruminants Contribute Fecal Contamination to the Urban Household Environment in Dhaka, Bangladesh ENVIRONMENTAL SCIENCE & TECHNOLOGY Harris, A. R., Pickering, A. J., Harris, M., Doza, S., Islam, M. S., Unicomb, L., Luby, S., Davis, J., Boehm, A. B. 2016; 50 (9): 4642-4649


    In Dhaka, Bangladesh, the sensitivity and specificity of three human, three ruminant, and one avian source-associated QPCR microbial source tracking assays were evaluated using fecal samples collected on site. Ruminant-associated assays performed well, whereas the avian and human assays exhibited unacceptable cross-reactions with feces from other hosts. Subsequently, child hand rinses (n = 44) and floor sponge samples (n = 44) from low-income-households in Dhaka were assayed for fecal indicator bacteria (enterococci, Bacteroidales, and Escherichia coli) and a ruminant-associated bacterial target (BacR). Mean enterococci concentrations were of 100 most probable number (MPN)/2 hands and 1000 MPN/225 cm(2) floor. Mean concentrations of Bacteroidales were 10(6) copies/2 hands and 10(5) copies/225 cm(2) floor. E. coli were detected in a quarter of hand rinse and floor samples. BacR was detected in 18% of hand rinse and 27% of floor samples. Results suggest that effective household fecal management should account not only for human sources of contamination but also for animal sources. The poor performance of the human-associated assays in the study area calls into the question the feasibility of developing a human-associated marker in urban slum environments, where domestic animals are exposed to human feces that have been disposed in pits and open drains.

    View details for DOI 10.1021/acs.est.5b06282

    View details for Web of Science ID 000375521400007

    View details for PubMedID 27045990

  • Field trial of an automated batch chlorinator system at shared water points in an urban community of Dhaka, Bangladesh JOURNAL OF WATER SANITATION AND HYGIENE FOR DEVELOPMENT Amin, N., Crider, Y. S., Unicomb, L., Das, K. K., Gope, P. S., Mahmud, Z. H., Islam, M. S., Davis, J., Luby, S. P., Pickering, A. J. 2016; 6 (1): 32-41
  • Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: a cluster-randomised controlled trial LANCET GLOBAL HEALTH Pickering, A. J., Djebbari, H., Lopez, C., Coulibaly, M., Laura Alzua, M. 2015; 3 (11): E701-E711
  • A Pilot Study on Integrating Videography and Environmental Microbial Sampling to Model Fecal Bacterial Exposures in Peri-Urban Tanzania PLOS ONE Julian, T. R., Pickering, A. J. 2015; 10 (8)
  • Differences in Field Effectiveness and Adoption between a Novel Automated Chlorination System and Household Manual Chlorination of Drinking Water in Dhaka, Bangladesh: A Randomized Controlled Trial PLOS ONE Pickering, A. J., Crider, Y., Amin, N., Bauza, V., Unicomb, L., Davis, J., Luby, S. P. 2015; 10 (3)
  • Genotypic and Phenotypic Characterization of Escherichia coli Isolates from Feces, Hands, and Soils in Rural Bangladesh via the Colilert Quanti-Tray System. Applied and environmental microbiology Julian, T. R., Islam, M. A., Pickering, A. J., Roy, S., Fuhrmeister, E. R., Ercumen, A., Harris, A., Bishai, J., Schwab, K. J. 2015; 81 (5): 1735-1743


    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. Evidence of the specificity of β-glucuronidase-based assays for detection of Escherichia coli from environmental matrices relevant to enteric pathogen transmission in developing countries, such as hands, soils, and surfaces, is limited. In this study, we quantify the false-positive rate of a β-glucuronidase-based E. coli detection assay (Colilert) for two environmental reservoirs in Bangladeshi households (hands and soils) and three fecal composite sources (cattle, chicken, and humans). We investigate whether or not the isolation source of E. coli influences phenotypic and genotypic characteristics. Phenotypic characteristics include results of biochemical assays provided by the API-20E test; genotypic characteristics include the Clermont phylogroup and the presence of enteric and/or environmental indicator genes sfmH, rfaI, and fucK. Our findings demonstrate no statistically significant difference in the false-positive rate of Colilert for environmental compared to enteric samples. E. coli isolates from all source types are genetically diverse, representing six of the seven phylogroups, and there is no difference in relative frequency of phylogroups between enteric and environmental samples. We conclude 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. Furthermore, 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.

    View details for DOI 10.1128/AEM.03214-14

    View details for PubMedID 25548044

  • Pilot Cluster Randomized Controlled Trials to Evaluate Adoption of Water, Sanitation, and Hygiene Interventions and Their Combination in Rural Western Kenya AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE Christensen, G., Dentz, H. N., Pickering, A. J., Bourdier, T., Arnold, B. F., Colford, J. M., Null, C. 2015; 92 (2): 437-447


    In preparation for a larger trial, the Water, Sanitation, and Hygiene (WASH) Benefits pilot study enrolled 72 villages and 499 subjects in two closely related randomized trials of WASH interventions in rural western Kenya. Intervention households received hardware and promotion for one of the following: water treatment, sanitation and latrine improvements, handwashing with soap, or the combination of all three. Interventions were clustered by village. A follow-up survey was conducted 4 months after intervention delivery to assess uptake. Intervention households were significantly more likely than controls to have chlorinated stored water (36-60 percentage point increases), covers over latrine drop holes (55-75 percentage point increases), less stool visible on latrine floors (16-47 percentage point reductions), and a place for handwashing (71-85 percentage point increases) with soap available (49-66 percentage point increases). The high uptake in all arms shows that combined interventions can achieve high short-term adoption rates if well-designed.

    View details for DOI 10.4269/ajtmh.14-0138

    View details for Web of Science ID 000349065400043

    View details for PubMedID 25422394

  • Differences in field effectiveness and adoption between a novel automated chlorination system and household manual chlorination of drinking water in Dhaka, Bangladesh: a randomized controlled trial. PloS one Pickering, A. J., Crider, Y., Amin, N., Bauza, V., Unicomb, L., Davis, J., Luby, S. P. 2015; 10 (3)


    The number of people served by networked systems that supply intermittent and contaminated drinking water is increasing. In these settings, centralized water treatment is ineffective, while household-level water treatment technologies have not been brought to scale. This study compares a novel low-cost technology designed to passively (automatically) dispense chlorine at shared handpumps with a household-level intervention providing water disinfection tablets (Aquatab), safe water storage containers, and behavior promotion. Twenty compounds were enrolled in Dhaka, Bangladesh, and randomly assigned to one of three groups: passive chlorinator, Aquatabs, or control. Over a 10-month intervention period, the mean percentage of households whose stored drinking water had detectable total chlorine was 75% in compounds with access to the passive chlorinator, 72% in compounds receiving Aquatabs, and 6% in control compounds. Both interventions also significantly improved microbial water quality. Aquatabs usage fell by 50% after behavioral promotion visits concluded, suggesting intensive promotion is necessary for sustained uptake. The study findings suggest high potential for an automated decentralized water treatment system to increase consistent access to clean water in low-income urban communities.

    View details for DOI 10.1371/journal.pone.0118397

    View details for PubMedID 25734448

  • A Pilot Study on Integrating Videography and Environmental Microbial Sampling to Model Fecal Bacterial Exposures in Peri-Urban Tanzania. PloS one Julian, T. R., Pickering, A. J. 2015; 10 (8)


    Diarrheal diseases are a leading cause of under-five mortality and morbidity in sub-Saharan Africa. Quantitative exposure modeling provides opportunities to investigate the relative importance of fecal-oral transmission routes (e.g. hands, water, food) responsible for diarrheal disease. Modeling, however, requires accurate descriptions of individuals' interactions with the environment (i.e., activity data). Such activity data are largely lacking for people in low-income settings. In the present study, we collected activity data and microbiological sampling data to develop a quantitative microbial exposure model for two female caretakers in peri-urban Tanzania. Activity data were combined with microbiological data of contacted surfaces and fomites (e.g. broom handle, soil, clothing) to develop example exposure profiles describing second-by-second estimates of fecal indicator bacteria (E. coli and enterococci) concentrations on the caretaker's hands. The study demonstrates the application and utility of video activity data to quantify exposure factors for people in low-income countries and apply these factors to understand fecal contamination exposure pathways. This study provides both a methodological approach for the design and implementation of larger studies, and preliminary data suggesting contacts with dirt and sand may be important mechanisms of hand contamination. Increasing the scale of activity data collection and modeling to investigate individual-level exposure profiles within target populations for specific exposure scenarios would provide opportunities to identify the relative importance of fecal-oral disease transmission routes.

    View details for DOI 10.1371/journal.pone.0136158

    View details for PubMedID 26295964

  • Microbiological Evaluation of the Efficacy of Soapy Water to Clean Hands: A Randomized, Non-Inferiority Field Trial AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE Amin, N., Pickering, A. J., Ram, P. K., Unicomb, L., Najnin, N., Homaira, N., Ashraf, S., Abedin, J., Islam, M. S., Luby, S. P. 2014; 91 (2): 415-423


    We conducted a randomized, non-inferiority field trial in urban Dhaka, Bangladesh among mothers to compare microbial efficacy of soapy water (30 g powdered detergent in 1.5 L water) with bar soap and water alone. Fieldworkers collected hand rinse samples before and after the following washing regimens: scrubbing with soapy water for 15 and 30 seconds; scrubbing with bar soap for 15 and 30 seconds; and scrubbing with water alone for 15 seconds. Soapy water and bar soap removed thermotolerant coliforms similarly after washing for 15 seconds (mean log10 reduction = 0.7 colony-forming units [CFU], P < 0.001 for soapy water; mean log10 reduction = 0.6 CFU, P = 0.001 for bar soap). Increasing scrubbing time to 30 seconds did not improve removal (P > 0.05). Scrubbing hands with water alone also reduced thermotolerant coliforms (mean log10 reduction = 0.3 CFU, P = 0.046) but was less efficacious than scrubbing hands with soapy water. Soapy water is an inexpensive and microbiologically effective cleansing agent to improve handwashing among households with vulnerable children.

    View details for DOI 10.4269/ajtmh.13-0475

    View details for Web of Science ID 000339863800037

  • Hand bacterial communities vary across two different human populations MICROBIOLOGY-SGM Hospodsky, D., Pickering, A. J., Julian, T. R., Miller, D., Gorthala, S., Boehm, A. B., Peccia, J. 2014; 160: 1144-1152


    This study utilized pyrosequencing-based phylogenetic library results to assess bacterial communities on the hands of women in Tanzania and compared these communities with bacteria assemblages on the hands of US women. Bacterial population profiles and phylogenetically based ordinate analysis demonstrated that the bacterial communities on hands were more similar for selected populations within a country than between the two countries considered. Organisms that have commonly been identified in prior human skin microbiome studies, including members of the Propionibacteriaceae, Staphylococcaceae and Streptococceacea families, were highly abundant on US hands and drove the clustering of US hand microbial communities into a distinct group. The most abundant bacterial taxa on Tanzanian hands were the soil-associated Rhodobacteraceae and Nocardioidaceae. These results help to expand human microbiome results beyond US and European populations, and the identification and abundance of soil-associated bacteria on Tanzanian hands demonstrated the important role of the environment in shaping the microbial communities on human hands.

    View details for DOI 10.1099/mic.0.075390-0

    View details for Web of Science ID 000339470100012

  • Video Surveillance Captures Student Hand Hygiene Behavior, Reactivity to Observation, and Peer Influence in Kenyan Primary Schools PLOS ONE Pickering, A. J., Blum, A. G., Breiman, R. F., Ram, P. K., Davis, J. 2014; 9 (3)


    In-person structured observation is considered the best approach for measuring hand hygiene behavior, yet is expensive, time consuming, and may alter behavior. Video surveillance could be a useful tool for objectively monitoring hand hygiene behavior if validated against current methods.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 and in-person observation captured similar rates of hand cleaning (absolute difference <5%, p = 0.74). Video surveillance documented higher hand cleaning rates (71%) when at least one other person was present at the hand cleaning station, compared to when a student was alone (48%; rate ratio  = 1.14 [95% CI 1.01-1.28]). Students increased hand cleaning rates during simultaneous video and in-person monitoring as compared to single-method monitoring, suggesting reactivity to each method of monitoring. This trend was documented at schools receiving a handwashing with soap intervention, but not at schools receiving a sanitizer intervention.Video surveillance of hand hygiene behavior yields results comparable to in-person observation among schools in a resource-constrained setting. Video surveillance also has certain advantages over in-person observation, including rapid data processing and the capability to capture new behavioral insights. 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.

    View details for DOI 10.1371/journal.pone.0092571

    View details for Web of Science ID 000333677500025

    View details for PubMedID 24676389

  • Enteric Pathogens in Stored Drinking Water and on Caregiver's Hands in Tanzanian Households with and without Reported Cases of Child Diarrhea PLOS ONE Mattioli, M. C., Boehm, A. B., Davis, J., Harris, A. R., Mrisho, M., Pickering, A. J. 2014; 9 (1)
  • Access to Waterless Hand Sanitizer Improves Student Hand Hygiene Behavior in Primary Schools in Nairobi, Kenya AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE Pickering, A. J., Davis, J., Blum, A. G., Scalmanini, J., Oyier, B., Okoth, G., Breiman, R. F., Ram, P. K. 2013; 89 (3): 411-418


    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. Two schools received a waterless hand sanitizer intervention, two schools received a handwashing with soap intervention, and two schools received no intervention. Hand cleaning after toileting was 82% at sanitizer schools (N = 2,507 events), 38% at soap schools (N = 3,429), and 37% at control schools (N = 2,797), which was measured by structured observation over 2 months. Students at sanitizer schools were 23% less likely to have observed rhinorrhea than control students (P = 0.02); reductions in student-reported gastrointestinal and respiratory illness symptoms were not statistically significant. 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.

    View details for DOI 10.4269/ajtmh.13-0008

    View details for Web of Science ID 000326129900004

    View details for PubMedID 23836575

  • Enterococcus spp on fomites and hands indicate increased risk of respiratory illness in child care centers AMERICAN JOURNAL OF INFECTION CONTROL Julian, T. R., Pickering, A. J., Leckie, J. O., Boehm, A. B. 2013; 41 (8): 728-733


    BACKGROUND: Surface-mediated transmission is a potential route for respiratory disease in child care centers, but evidence of its importance relative to other routes (eg, airborne) is limited. METHODS: We tracked respiratory disease and monitored bacteria contamination on hands and fomites over 4 months during 64 visits at 2 child care centers. Staff monitored health daily by recording respiratory symptoms. We measured concentrations of Escherichia coli, Enterococcus spp, and fecal coliform in hand rinses and on select fomites. RESULTS: We demonstrated that symptomatic respiratory illness was positively associated with microbial contamination on hands and fomites, as measured using Enterococcus spp. Enterococcus spp were 0.28 (95% confidence interval: 0.08-0.48)-log(10) (colony-forming units per 2 hands) higher when an individual had symptomatic respiratory illness. Susceptible individuals were 1.62 (95% confidence interval: 1.06-2.46) times more likely to develop respiratory illness within 4 days with every log(10) increase of Enterococcus spp on hands. CONCLUSION: The findings imply that hand contamination as measured using Enterococcus spp is a risk factor for onset of respiratory illness and highlight the utility of fecal indicator bacteria as a metric for hand and fomite contamination.

    View details for DOI 10.1016/j.ajic.2012.10.013

    View details for Web of Science ID 000322641100014

    View details for PubMedID 23394857

  • Hands and Water as Vectors of Diarrhea! Pathogens in Bagannoyo, Tanzania ENVIRONMENTAL SCIENCE & TECHNOLOGY Mattioli, M. C., Pickering, A. J., Gilsdorf, R. J., Davis, J., Boehm, A. B. 2013; 47 (1): 355-363


    Diarrheal disease is a leading cause of under-five childhood mortality worldwide, with at least half of these deaths occurring in sub-Saharan Africa. Transmission of diarrheal pathogens occurs through several exposure routes including drinking water and hands, but the relative importance of each route is not well understood. 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. Viruses were most frequently found on hands, suggesting that hands are important vectors for viral illness. The occurrence of E. coli virulence genes (ECVG) was equivalent across all sample types, indicating that both water and hands are important for bacterial pathogen transmission. Fecal indicator bacteria and turbidity were good predictors of ECVG, whereas turbidity and human-specific Bacteroidales were good predictors of viruses. ECVG were more likely found in unimproved water sources, but both ECVG and viral genes were detected in improved water sources. ECVG were more likely found in stored water of households with unimproved sanitation facilities. The results provide insights into the distribution of pathogens in Tanzanian households and offer evidence that hand-washing and improved water management practices could alleviate viral and bacterial diarrhea.

    View details for DOI 10.1021/es303878d

    View details for Web of Science ID 000313220300046

  • 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. BMJ open Arnold, B. F., Null, C., Luby, S. P., Unicomb, L., Stewart, C. P., Dewey, K. G., Ahmed, T., Ashraf, S., Christensen, G., Clasen, T., Dentz, H. N., Fernald, L. C., Haque, R., Hubbard, A. E., Kariger, P., Leontsini, E., Lin, A., Njenga, S. M., Pickering, A. J., Ram, P. K., Tofail, F., Winch, P. J., Colford, J. M. 2013; 3 (8)


    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.WASH Benefits includes two cluster-randomised trials to assess improvements in water quality, sanitation, handwashing and child nutrition-alone and in combination-to rural households with pregnant women in Kenya and Bangladesh. Geographically matched clusters (groups of household compounds in Bangladesh and villages in Kenya) will be randomised to one of six intervention arms or control. Intervention arms include water quality, sanitation, handwashing, nutrition, combined water+sanitation+handwashing (WSH) and WSH+nutrition. The studies will enrol newborn children (N=5760 in Bangladesh and N=8000 in Kenya) and measure outcomes at 12 and 24 months after intervention delivery. Primary outcomes include child length-for-age Z-scores and caregiver-reported diarrhoea. Secondary outcomes include stunting prevalence, markers of environmental enteropathy and child development scores (verbal, motor and personal/social). We will estimate unadjusted and adjusted intention-to-treat effects using semiparametric estimators and permutation tests.Study protocols have been reviewed and approved by human subjects review boards at the University of California, Berkeley, Stanford University, the International Centre for Diarrheal Disease Research, Bangladesh, the Kenya Medical Research Institute, and Innovations for Poverty Action. Independent data safety monitoring boards in each country oversee the trials. This study is funded by a grant from the Bill & Melinda Gates Foundation to the University of California, Berkeley.Trial registration identifiers ( NCT01590095 (Bangladesh), NCT01704105 (Kenya).

    View details for DOI 10.1136/bmjopen-2013-003476

    View details for PubMedID 23996605

  • Fecal Contamination and Diarrheal Pathogens on Surfaces and in Soils among Tanzanian Households with and without Improved Sanitation ENVIRONMENTAL SCIENCE & TECHNOLOGY Pickering, A. J., Julian, T. R., Marks, S. J., Mattioli, M. C., Boehm, A. B., Schwab, K. J., Davis, J. 2012; 46 (11): 5736-5743


    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 of fecal contamination and selected diarrheal pathogens in soil (n = 200), surface (n = 120), and produce samples (n = 24) was conducted in peri-urban Bagamoyo, Tanzania, among 20 households using private pit latrines. All samples were analyzed for E. coli and enterococci. A subset was analyzed for enterovirus, rotavirus, norovirus GI, norovirus GII, diarrheagenic E. coli, and general and human-specific Bacteroidales fecal markers using molecular methods. Soil collected from the house floor had significantly higher concentrations of E. coli and enterococci than soil collected from the latrine floor. There was no significant difference in fecal indicator bacteria levels between households using pit latrines with a concrete slab (improved sanitation) versus those without a slab. These findings imply that the presence of a concrete slab does not affect the level of fecal contamination in the household environment in this setting. Human Bacteroidales, pathogenic E. coli, enterovirus, and rotavirus genes were detected in soil samples, suggesting that soil should be given more attention as a transmission pathway of diarrheal illness in low-income countries.

    View details for DOI 10.1021/es300022c

    View details for Web of Science ID 000304783000017

    View details for PubMedID 22545817

  • Freshwater Availability and Water Fetching Distance Affect Child Health in Sub-Saharan Africa ENVIRONMENTAL SCIENCE & TECHNOLOGY Pickering, A. J., Davis, J. 2012; 46 (4): 2391-2397


    Currently, more than two-thirds of the population in Africa must leave their home to fetch water for drinking and domestic use. The time burden of water fetching has been suggested to influence the volume of water collected by households as well as time spent on income generating activities and child care. However, little is known about the potential health benefits of reducing water fetching distances. Data from almost 200,?000 Demographic and Health Surveys carried out in 26 countries were used to assess the relationship between household walk time to water source and child health outcomes. To estimate the causal effect of decreased water fetching time on health, geographic variation in freshwater availability was employed as an instrumental variable for one-way walk time to water source in a two-stage regression model. Time spent walking to a household's main water source was found to be a significant determinant of under-five child health. 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.

    View details for DOI 10.1021/es203177v

    View details for Web of Science ID 000300465900056

    View details for PubMedID 22242546

  • Bacterial hand contamination among Tanzanian mothers varies temporally and following household activities TROPICAL MEDICINE & INTERNATIONAL HEALTH Pickering, A. J., Julian, T. R., Mamuya, S., Boehm, A. B., Davis, J. 2011; 16 (2): 233-239


    To characterize mechanisms of hand contamination with faecal indicator bacteria and to assess the presence of selected pathogens on mothers' hands in Tanzania.A household observational study combined with repeated microbiological hand rinse sampling was conducted among 119 mothers in Dar es Salaam, Tanzania. All hand rinse samples were analysed for enterococci and Escherichia coli, and selected samples were analysed for genetic markers of Bacteroidales, enterovirus and pathogenic E. coli.Using the toilet, cleaning up a child's faeces, sweeping, cleaning dishes, preparing food and bathing were all found to increase faecal indicator bacterial levels on hands. Geometric mean increases in colony forming units per two hands ranged from 50 (cleaning dishes) to 6310 (food preparation). Multivariate modelling of hand faecal indicator bacteria as a function of activities recently performed shows that food handling, exiting the household premises and longer time since last handwashing with soap are positively associated with bacterial levels on hands, while bathing is negatively associated. Genetic markers of Bacteroidales, enterovirus and pathogenic E. coli were each detected on a subset of mothers' hands.Escherichia coli and enterococci on hands can be significantly increased by various household activities, including those involving the use of soap and water. Thus, faecal indicator bacteria should be considered highly variable when used as indicators of handwashing behaviour. This work corroborates hands as important vectors of disease among Tanzanian mothers and highlights the difficulty of good personal hygiene in an environment characterized by the lack of networked sanitation and water supply services.

    View details for DOI 10.1111/j.1365-3156.2010.02677.x

    View details for Web of Science ID 000286116500015

    View details for PubMedID 21091858

  • The Effects of Informational Interventions on Household Water Management, Hygiene Behaviors, Stored Drinking Water Quality, and Hand Contamination in Peri-Urban Tanzania AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE Davis, J., Pickering, A. J., Rogers, K., Mamuya, S., Boehm, A. B. 2011; 84 (2): 184-191


    Safe water storage and hand hygiene have been shown to reduce fecal contamination and improve health in experimental settings; however, triggering and sustaining such behaviors is challenging. This study investigates the extent to which personalized information about Escherichia coli contamination of stored water and hands influenced knowledge, reported behaviors, and subsequent contamination levels among 334 households with less than 5-year-old children in peri-urban Dar es Salaam, Tanzania. One-quarter of the study participants received information about strategies to reduce risk of water- and sanitation-related illness. Respondents in another three study cohorts received this same information, along with their household's water and/or hand-rinse test results. Findings from this study suggest that additional work is needed to elucidate the conditions under which such testing represents a cost-effective strategy to motivate improved household water management and hand hygiene.

    View details for DOI 10.4269/ajtmh.2011.10-0126

    View details for Web of Science ID 000287003900002

    View details for PubMedID 21292883

  • Efficacy of alcohol-based hand sanitizer on hands soiled with dirt and cooking oil JOURNAL OF WATER AND HEALTH Pickering, A. J., Davis, J., Boehm, A. B. 2011; 9 (3): 429-433


    Handwashing education and promotion are well established as effective strategies to reduce diarrhea and respiratory illness in countries around the world. However, access to reliable water supplies has been identified as an important barrier to regular handwashing in low-income countries. Alcohol-based hand sanitizer (ABHS) is an effective hand hygiene method that does not require water, but its use is not currently recommended when hands are visibly soiled. This study evaluated the efficacy of ABHS on volunteers' hands artificially contaminated with Escherichia coli in the presence of dirt (soil from Tanzania) and cooking oil. ABHS reduced levels of E. coli by a mean of 2.33 log colony forming units (CFU) per clean hand, 2.32 log CFU per dirt-covered hand, and 2.13 log CFU per oil-coated hand. No significant difference in efficacy was detected between hands that were clean versus dirty or oily. ABHS may be an appropriate hand hygiene method for hands that are moderately soiled, and an attractive option for field settings in which access to water and soap is limited.

    View details for DOI 10.2166/wh.2011.138

    View details for Web of Science ID 000293624300001

    View details for PubMedID 21976190

  • Understanding household behavioral risk factors for diarrheal disease in Dar es Salaam: a photovoice community assessment. Journal of environmental and public health Badowski, N., Castro, C. M., Montgomery, M., Pickering, A. J., Mamuya, S., Davis, J. 2011; 2011: 130467-?


    Whereas Tanzania has seen considerable improvements in water and sanitation infrastructure over the past 20 years, the country still faces high rates of childhood morbidity from diarrheal diseases. This study utilized a qualitative, cross-sectional, modified Photovoice method to capture daily activities of Dar es Salaam mothers. A total of 127 photographs from 13 households were examined, and 13 interviews were conducted with household mothers. The photographs and interviews revealed insufficient hand washing procedures, unsafe disposal of wastewater, uncovered household drinking water containers, a lack of water treatment prior to consumption, and inappropriate toilets for use by small children. The interviews revealed that mothers were aware and knowledgeable of the risks of certain household practices and understood safer alternatives, yet were restricted by the perceived impracticality and financial constraints to make changes. The results draw attention to the real economic and behavioral challenges faced in reducing the spread of disease.

    View details for DOI 10.1155/2011/130467

    View details for PubMedID 21969836

  • Hands, Water, and Health: Fecal Contamination in Tanzanian Communities with Improved, Non-Networked Water Supplies ENVIRONMENTAL SCIENCE & TECHNOLOGY Pickering, A. J., Davis, J., Walters, S. P., Horak, H. M., Keymer, D. P., Mushi, D., Strickfaden, B., Chynoweth, J. S., Liu, J., Blum, A., Rogers, K., Boehm, A. B. 2010; 44 (9): 3267-3272


    Almost half of the world's population relies on non-networked water supply services, which necessitates in-home water storage. It has been suggested that dirty hands play a role in microbial contamination of drinking water during collection, transport, and storage. However, little work has been done to evaluate quantitatively the association between hand contamination and stored water quality within households. This study measured levels of E. coli, fecal streptococci, and occurrence of the general Bacteroidales fecal DNA marker in source water, in stored water, and on hands in 334 households among communities in Dar es Salaam, Tanzania, where residents use non-networked water sources. Levels of fecal contamination on hands of mothers and children were positively correlated to fecal contamination in stored drinking water within households. Household characteristics associated with hand contamination included mother's educational attainment, use of an improved toilet, an infant in the household, and dissatisfaction with the quantity of water available for hygiene. In addition, fecal contamination on hands was associated with the prevalence of gastrointestinal and respiratory symptoms within a household. The results suggest that reducing fecal contamination on hands should be investigated as a strategy for improving stored drinking water quality and health among households using non-networked water supplies.

    View details for DOI 10.1021/es903524m

    View details for Web of Science ID 000277067000014

    View details for PubMedID 20222746

  • Efficacy of Waterless Hand Hygiene Compared with Handwashing with Soap: A Field Study in Dar es Salaam, Tanzania AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE Pickering, A. J., Boehm, A. B., Mwanjali, M., Davis, J. 2010; 82 (2): 270-278


    Effective handwashing with soap requires reliable access to water supplies. However, more than three billion persons do not have household-level access to piped water. This research addresses the challenge of improving hand hygiene within water-constrained environments. The antimicrobial efficacy of alcohol-based hand sanitizer, a waterless hand hygiene product, was evaluated and compared with handwashing with soap and water in field conditions in Dar es Salaam, Tanzania. Hand sanitizer use by mothers resulted in 0.66 and 0.64 log reductions per hand of Escherichia coli and fecal streptococci, respectively. In comparison, handwashing with soap resulted in 0.50 and 0.25 log reductions per hand of E. coli and fecal streptococci, respectively. Hand sanitizer was significantly better than handwashing with respect to reduction in levels of fecal streptococci (P = 0.01). The feasibility and health impacts of promoting hand sanitizer as an alternative hand hygiene option for water-constrained environments should be assessed.

    View details for DOI 10.4269/ajtmh.2010.09-0220

    View details for Web of Science ID 000274263300018

    View details for PubMedID 20134005