Biology subjects

Cumming, O.

Publications and source records attributed to Cumming, O..

4 recordsLinked to original sources

bioRxiv2021

Impact of an Urban Sanitation Intervention on Enteric Pathogen Detection in Soils

Environmental fecal contamination is common in many low-income cities, contributing to a high burden of enteric infections and associated negative sequelae. To evaluate the impact of a shared onsite sanitation intervention in Maputo, Mozambique on enteric pathogens in the domestic environment, we collected 179 soil samples at shared latrine entrances from intervention (n= 49) and control (n= 51) compounds during baseline (pre-intervention) and after 24 months (post-intervention) as part of the Maputo Sanitation Trial. We tested soils for the presence of nucleic acids associated with 20 enteric pathogens using a multiplex reverse transcription qPCR platform. We detected at least one pathogen-associated target in 91% (163/179) of soils and a median of 3 (IQR=1.5, 5) pathogens. Using a difference-in-difference analysis and adjusting for compound population, visibly wet soil, sun exposure, wealth, temperature, animal presence, and visible feces, we estimate the intervention reduced the probability of [≥]1 pathogen detected by 15% (adjusted prevalence ratio, aPR=0.85; 95% CI: 0.70, 1.0) and the total number of pathogens detected by 35% (aPR =0.65; 0.44, 0.95) in soil 24 months following the intervention. These results suggest that the intervention reduced the presence of some fecal contamination in the domestic environment, but pathogen detection remained prevalent 24-months following the introduction of new latrines.

molecular biology↗

bioRxiv2021

Bayesian analysis of source tracking markers to estimate the effects of an urban sanitation intervention on human fecal contamination in Mozambique

Fecal source tracking (FST) may be useful to assess pathways of fecal contamination in domestic environments and to estimate the impacts of water, sanitation, and hygiene (WASH) interventions in low-income settings. We measured two non-specific and two human-associated fecal indicators in water, soil, and surfaces before and after a shared latrine intervention from low-income households in Maputo, Mozambique participating in the Maputo Sanitation (MapSan) trial. Up to a quarter of households were impacted by human fecal contamination, but trends were unaffected by improvements to shared sanitation facilities. The intervention reduced E. coli gene concentrations in soil but did not impact culturable E. coli or the prevalence of human FST markers in a difference-in-differences analysis. Using a novel Bayesian hierarchical modeling approach to account for human marker diagnostic sensitivity and specificity, we revealed a high amount of uncertainty associated with human FST measurements and intervention effect estimates. The field of microbial source tracking would benefit from adding measures of diagnostic accuracy to better interpret findings, particularly when FST analyses convey insufficient information for robust inference. With improved measures, FST could help identify dominant pathways of human and animal fecal contamination in communities and guide implementation of effective interventions to safeguard health. SYNOPSISAn urban sanitation intervention had minimal and highly uncertain effects on human fecal contamination after accounting for fecal indicator sensitivity and specificity. TOC GRAPHIC/ABSTRACT ART O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=108 SRC="FIGDIR/small/432000v2_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@312d2dorg.highwire.dtl.DTLVardef@8cf2caorg.highwire.dtl.DTLVardef@197b549org.highwire.dtl.DTLVardef@fefeb3_HPS_FORMAT_FIGEXP M_FIG C_FIG

microbiology↗

bioRxiv2018

Enteric Pathogen Diversity in Infant Foods in Low-income Neighborhoods Of Kisumu, Kenya

Pediatric diarrheal disease remains the 2nd most common cause of preventable illness and death among children under the age of five, especially in Low and Middle-Income Countries (LMICs). However, there is limited information regarding the role of food in pathogen transmission due to measuring infant food contaminations in LMICs. For this study, we examined the frequency of enteric pathogen occurrence and co-occurrence in 127 weaning infant foods in Kisumu, Kenya using a multi-pathogen rt-PCR diagnostic tool, and assessed household food hygiene risk factors for contamination. Bacterial, viral, and protozoa enteric pathogen DNA and RNA were detected in 62% of the infant weaning food samples collected, with 37% of foods containing more than one pathogen type. Multivariable generalized linear mixed model analysis indicated type of infant food best explained the presence and diversity of enteric pathogens in infant food, while most household food hygiene risk factors considered in this study were not significantly associated with pathogen contamination. Specifically, cows milk was significantly more likely to contain a pathogen (adjusted Risk Ratio=14.4; 95% Confidence Interval (CI) 1.78-116.1) and contained 2.35 more types of pathogens (adjusted Risk Ratio=2.35; 95% CI 1.67-3.29) than porridge. Our study demonstrates that infants in this low-income urban setting are frequently exposed to diarrhoeagenic pathogens in food and suggests that interventions are needed to prevent foodborne transmission of pathogens to infants.\n\nImportanceFood is acknowledged as an important pathway for enteric pathogen infection in young children. Yet, information on enteric pathogen contamination in food in low-and-middle income settings is lacking, especially with respect to weaning foods given to young infants. This study assessed which food-related risk factors were associated with increased presence of and diversity in twenty-seven types of enteric pathogens in a variety of foods provided to infants between three and nine months of age in a low-income neighborhood of Kisumu, Kenya. Feeding infants cow milk emerged as the most important risk factor for food contamination by one or more enteric pathogens. The results indicate public health interventions should focus on improving cow milk safety to prevent foodborne pathogen transmission to infants. However, more research is needed to determine whether infant milk contamination was caused by caregiver hygiene practices versus food contamination passed from upstream sources.

microbiology↗

bioRxiv2018

The Landscape of Enteric Pathogen Exposure of Young Children in Public Domains of Low-Income, Urban Kenya: The Influence of Exposure Pathway and Spatial Range of Play on Multi-Pathogen Exposure Risks

BackgroundYoung children are infected by a diverse variety of enteric pathogens in low-income, high-burden countries. Little is known about which conditions pose the greatest risk for enteric pathogen exposure and infection. Young children frequently play in residential public areas around their household, including areas contaminated by human and animal feces, suggesting these exposures are particularly hazardous.\n\nObjectivesThe objective of this study was to examine how the dose of six types of common enteric pathogens, and the probability of exposure to one or multiple enteric pathogens for young children playing at public play areas in Kisumu, Kenya is influenced by the type and frequency of child play behaviors that result in ingestion of soil or surface water, as well as by spatial variability in the number of public areas children are exposed to in their neighborhood.\n\nMethodsA Bayesian framework was employed to obtain the posterior distribution of pathogen doses for a certain number of contacts. First, a multivariate random effects tobit model was used to obtain the posterior distribution of pathogen concentrations, and their interdependencies, in soil and surface water, based upon empirical data of enteric pathogen contamination in three neighborhoods of Kisumu. Then, exposure doses were estimated using behavioral contact parameters from previous studies, and contrasted under different exposure conditions.\n\nResultsMulti-pathogen exposure of children at public play areas was common. Pathogen doses and the probability of multi-pathogen ingestion increased with: higher frequency of environmental contact, especially for surface water; larger volume of soil or water ingested; and with play at multiple sites in the neighborhood versus single site play.\n\nDiscussionChild contact with surface water and soil at public play areas in their neighborhood is an important cause of exposure to enteric pathogens in Kisumu, and behavioral, environmental, and spatial conditions are determinants of exposure.

microbiology↗