Environmental Factors Associated with High Fly Densities and Diarrhea in Vellore, India

Unraveling diarrheal disease knowledge, understanding, and management practices among climate change vulnerable coastal communities in Ghana

Introduction

Diarrheal disease is a global public health concern, particularly in low-income countries. In Ghana, widespread issues like inadequate sanitation, unsafe drinking water, malnutrition, and poor hygiene practices contribute to the high incidence of diarrhea. Climate change exacerbates these challenges by increasing the frequency and severity of conditions that spread diarrheal diseases. This study explores households' knowledge, understanding, and management practices for diarrhea in climate change-vulnerable coastal communities.

Methods

The study is set in Ghana's central (Mumford, Opetekwei) and eastern (Anyako, Anyanui-Atiteti) coastlines. Using a cross-sectional study design, a structured questionnaire was administered to randomly sampled households (n = 419) to collect quantitative data. The study collected qualitative data from focus group discussions (n = 8), with groups separated into men and women, key informant interviews, and observations of food, water, and sanitation conditions across the studied communities.

Results and discussion

The study found significant variations between the studied communities and socio-demographic variables except for the respondents' gender. Multivariate regression analyses identified significant associations between socio-demographic variables (especially gender and educational status) and perceptions of diarrhea causes. The most used first management action against diarrhea is 'over-the-counter drugs', followed by home-made traditional remedies. Significant differences were observed in the usage of management practices across the studied communities. Trust, affordability, and availability were identified as the main factors influencing households' use of approved pharmaceutical drugs and traditional herbal remedies for managing behavior, with significant differences being observed across communities. The study recommends a multi-sectoral approach, including improved access to regularly flowing, safe water and sanitation facilities, education on preventing diarrhea, and adequate healthcare services. Community-based interventions such as promoting good hygiene practices at homes and community settings such as schools, lorry parks, funeral grounds, and recreational areas can also effectively reduce the burden of diarrhea.

Unveiling the hidden dangers: enteropathogens carried by flies in Pudong New Area

BACKGROUND

Flies are acknowledged as vectors of diseases transmitted through mechanical means and represent a significant risk to human health. The study aimed to determine the prevalence of enteropathogens carried by flies in Pudong New Area to inform strategies for preventing and controlling flies.

METHODS

Samples were collected from various locations in the area using cage trapping techniques between April and November 2021, encompassing various habitats such as parks, residential areas, restaurants, and farmers' markets. The main fly species were identified using cryomicrography and taxonomic enumeration, with 20 samples per tube collected from different habitats. Twenty-five enteropathogens were screened using GI_Trial v3 TaqManTM microbial arrays.

RESULTS

A total of 3,875 flies were collected from 6,400 placements, resulting in an average fly density of 0.61 flies per cage. M. domestica were the most common species at 39.85%, followed by L. sericata at 16.57% and B. peregrina at 13.14%. Out of 189 samples, 93 tested positive for enteropathogens, with nine different pathogens being found. 12.70% of samples exclusively had parasites, a higher percentage than those with only bacteria or viruses. The study found that M. domestica had fewer enteropathogens than L. sericata and B. peregrina, which primarily harbored B. hominis instead of bacteria and viruses such as E. coli, Astrovirus, and Sapovirus. During spring testing, all three fly species exhibited low rates of detecting enteropathogens. M. domestica were found in residential areas with the highest number of pathogen species, totaling six. In contrast, L. sericata and B. peregrina were identified in farmers' markets with the highest number of pathogen species, totaling six and seven, respectively.

CONCLUSIONS

Flies have the potential to serve as vectors for the transmission of enteropathogens, thereby posing a substantial risk to public health.

The global prevalence of parasites in non-biting flies as vectors: a systematic review and meta-analysis

BACKGROUND

Non-biting flies such as the house fly (Musca domestica), the Australian sheep blowfly (Lucilia cuprina) and the oriental latrine fly (Chrysomya megacephala) may carry many parasites. In the present study, we performed a systematic overview of the different species of parasites carried by non-biting flies, as well as of isolation methods, different geographical distribution, seasonality and risk assessment.

METHODS

A meta-analysis was carried out with the aim to review the global prevalence of parasite transmission in non-biting flies. A total sample size of 28,718 non-biting flies reported in studies worldwide satisfied the predetermined selection criteria and was included in the quantitative analysis.

RESULTS

The global prevalence of parasites in non-biting flies was 42.5% (95% confidence interval [CI] 31.9-53.2%; n = 15,888/28,718), with the highest prevalence found for non-biting flies in Africa (58.3%; 95% CI 47.4-69.3%; n = 9144/13,366). A total of 43% (95% CI 32.1-54.4%; n = 7234/15,282) of house flies (M. domestica), the fly species considered to be the most closely associated with humans and animals, were found with parasites. The prevalence of parasites in the intestine of non-biting flies was 37.1% (95% CI 22.7-51.5%; n = 1045/3817), which was significantly higher than the prevalence of parasites isolated from the body surface (35.1%; 95% CI 20.8-49.4%; n = 1199/3649; P < 0.01). Of the 27 reported parasites, a total of 20 known zoonotic parasites were identified, with an infection rate of 38.1% (95% CI 28.2-48.0%; n = 13,572/28,494).

CONCLUSIONS

This study provides a theoretical basis for the public health and ecological significance of parasites transmitted by non-biting flies.

Urban Onsite Sanitation Upgrades and Synanthropic Flies in Maputo, Mozambique: Effects on Enteric Pathogen Infection Risks

Synanthropic filth flies transport enteric pathogens from feces to food, which upon consumption poses an infection risk. We evaluated the effect of an onsite sanitation intervention─including fly control measures─in Maputo, Mozambique, on the risk of infection from consuming fly-contaminated food. After enumerating flies at intervention and control sites, we cultured fecal indicator bacteria, quantified gene copies for 22 enteric pathogens via reverse transcription quantitative polymerase chain reaction (RT-qPCR), and developed quantitative microbial risk assessment (QMRA) models to estimate annual risks of infection attributable to fly-contaminated foods. We found that the intervention reduced fly counts at latrine entrances by 69% (aRR = 0.31, [0.13, 0.75]) but not at food preparation areas (aRR = 0.92, [0.33, 2.6]). Half of (23/46) of individual flies were positive for culturable Escherichia coli, and we detected ≥1 pathogen gene from 45% (79/176) of flies, including enteropathogenic E. coli (37/176), adenovirus (25/176), Giardia spp. (13/176), and Trichuris trichiura (12/176). We detected ≥1 pathogen gene from half the flies caught in control (54%, 30/56) and intervention compounds (50%, 17/34) at baseline, which decreased 12 months post-intervention to 43% (23/53) at control compounds and 27% (9/33) for intervention compounds. These data indicate flies as a potentially important mechanical vector for enteric pathogen transmission in this setting. The intervention may have reduced the risk of fly-mediated enteric infection for some pathogens, but infrequent detection resulted in wide confidence intervals; we observed no apparent difference in infection risk between groups in a pooled estimate of all pathogens assessed (aRR = 0.84, [0.61, 1.2]). The infection risks posed by flies suggest that the design of sanitation systems and service delivery should include fly control measures to prevent enteric pathogen transmission.

Prevalence of Antibiotic-Resistant E. coli Strains in a Local Farm and Packing Facilities of Honeydew Melon in Hermosillo, Sonora, Mexico

Pathogenic strains of Escherichia coli threaten public health due to their virulence factors and antibiotic resistance. Additionally, the virulence of this bacterium varies by region depending on environmental conditions, agricultural practices, and the use of antibiotics and disinfectants. However, there is limited research on the prevalence of antibiotic-resistant E. coli in agriculture. Therefore, this research aimed to determine the antibiotic resistance of E. coli isolated from the Honeydew melon production system in Hermosillo, Sonora, Mexico. Thirty-two E. coli strains were isolated from 445 samples obtained from irrigation water, harvested melons, the hands of packaging workers, boxes, and discarded melons. The resistance profile of the E. coli strains was carried out to 12 antibiotics used in antimicrobial therapeutics against this bacterium; a high level of resistance to ertapenem (100%) was detected, followed by meropenem (97%), and ampicillin (94%); 47% of the strains were classified as multidrug-resistant. It was possible to identify the prevalence of the extended-spectrum β-lactamase (ESBLs) gene bla_TEM (15.6%), as well as the non-ESBL genes qepA (3.1%) and aac(6')lb-cr (3.1%). The E. coli strains isolated from irrigation water were significantly associated with resistance to aztreonam, cefuroxime, amikacin, and sulfamethoxazole/trimethoprim. Irrigation water, packing workers' hands, and discarded melons showed a higher prevalence of antibiotic-resistant, ESBL, and non-ESBL genes of E. coli strains in a farm and packing facility of Honeydew melon in Hermosillo, Sonora.

The Burden of Diarrheal Diseases and Its Associated Factors among Under-Five Children in Welkite Town: A Community Based Cross-Sectional Study

Objective: This study assessed the magnitude of diarrhea and associated risk factors among under-five children in Welkite town.

Methods: We used a community-based cross-sectional study design. Data collection period was February to March 2021 and 426 parents/guardians of under-five children were the study participants. A structured questionnaire and observation checklist were used to collect the data.

Results: The 2 weeks prevalence of diarrhea among under-five years old children was 20.7% (88/426); 95% CI (17.1, 24.6). The child’s mother/caregiver being merchant (AOR: 5.34; 95% CI: 2.1, 13.8) compared to housewife, partial immunization status (AOR: 2.67; 95% CI: 1.2, 5.8), disposing child’s stool into the garbage (AOR: 5.05; 95% CI: 1.1, 23.3) compared to putting in a toilet, not covering water storage materials (AOR: 2.4; 95% CI: 1.2, 4.7) and presence of flies in food preparation area (AOR: 2.24; 95% CI: 1.05, 4.8) were associated with increased odds of having diarrhea.

Conclusion: The prevalence of diarrhea among under-five old children is high and it is associated with the occupation of the mothers/caregivers, the immunization status of children, unhygienic water storage condition and non-hygienic household practice.

ERIC-PCR based molecular typing of multidrug resistant Escherichia coli isolated from houseflies (Musca domestica) in the environment of milk and meat shops

The emergence and spread of antimicrobial resistance has become a major global public health concern. A component of this problem is the spread of the antibiotic resistant bacteria. Flies move freely between habitats of food-producing animals and human beings and thus have great potential for dissemination of antimicrobial resistant bacteria from a contaminated environment to milk and meat markets, posing potential hazards for the consumers. During the present study, a total of 150 houseflies were captured from milk and meat shops located in Durg and Raipur city of Chhattisgarh, India. The E. coli were isolated from houseflies and characterized on the basis of cultural and molecular tests. Further, the isolates were subjected to antimicrobial susceptibility testing against frequently used antibiotics using disk diffusion method. The antibiotic resistance genes and int1 gene were detected using polymerase chain reaction (PCR). A total of 45 E. coli isolates were obtained from the fly samples with overall prevalence rate of 30.0%. Antibiogram results confirmed that E. coli isolates were resistant to multiple antibiotics. Out of the (45) isolates of E. coli, 17 (37.8%) isolates were extended spectrum beta-lactamase (ESBL) producer and multi-drug resistant (MDR). Out of the ESBL and MDR E.coli isolates, bla_CTX-M (24.4%), bla_TEM (11.1%), tetA (28.8%), tetB (26.7%), gyrA (26.7%), parC (31. 1%) and int1 genes (15.5%) were detected but none of the isolates were found positive for bla_SHV gene. Findings of the present study confirm that MDR E. coli are widely distributed in houseflies and play an important role in transmission of antibiotic-resistant bacteria from contaminated environment to milk and meat shop environment.

Detection of Escherichia coli, rotavirus, and Cryptosporidium spp. from drinking water, kitchenware, and flies in a periurban community of Lusaka, Zambia

Fecal contamination with a poor water, sanitation and hygiene environment in urban informal settlements poses diarrhea risks. Little information is available on the contamination of environmental media with enteric pathogens in such settlements. We investigated the contamination of Escherichia coli, rotavirus, and Cryptosporidium spp. in water, on kitchenware, and on flies in urban informal settlements of Chawama and Kanyama, Lusaka, Zambia. These environmental media were examined by XM-G agar cultivation for E. coli and specific real-time RT-PCR assays to detect rotavirus and Cryptosporidium spp. E. coli; rotavirus, and Cryptosporidium spp. were detected in samples of household stored drinking water (6 of 10 samples, 3 of 10 samples, and 2 of 10 samples, respectively), cups (10 of 20 samples, 2 of 13 samples, 1 of 13 samples, respectively), and flies (35 of 55 samples, 5 of 17 samples, 1 of 17 samples, respectively). The ranges of rotavirus concentrations in household stored drinking water, on cups, and flies were 2.9 × 10²-2.2 × 10⁵ copies/L, 1.2 × 10²-4.3 × 10² copies/cup, and 5.0 × 10¹-2.0 × 10² copies/fly, respectively. These results indicate the contribution of drinking water and kitchenware to enteric pathogen exposure and potential role of flies in microbial transmission.

Rotaviruses: From Pathogenesis to Disease Control—A Critical Review

Since their first recognition in human cases about four decades ago, rotaviruses have remained the leading cause of acute severe dehydrating diarrhea among infants and young children worldwide. The WHO prequalification of oral rotavirus vaccines (ORV) a decade ago and its introduction in many countries have yielded a significant decline in the global burden of the disease, although not without challenges to achieving global effectiveness. Poised by the unending malady of rotavirus diarrhea and the attributable death cases in developing countries, we provide detailed insights into rotavirus biology, exposure pathways, cellular receptors and pathogenesis, host immune response, epidemiology, and vaccination. Additionally, recent developments on the various host, viral and environmental associated factors impacting ORV performance in low-and middle-income countries (LMIC) are reviewed and their significance assessed. In addition, we review the advances in nonvaccine strategies (probiotics, candidate anti-rotaviral drugs, breastfeeding) to disease prevention and management.

Barriers to cleaning of shared latrines in slums of Addis Ababa, Ethiopia

Shared latrines and other shared sanitation facilities are vital for communities that lack private latrines. However, the cleanliness of shared latrines continues to be a problem in sub-Saharan Africa, including slums of Addis Ababa, Ethiopia. Investigating the barriers to cleaning of shared latrines may inform the future strengthening of comprehensive sanitation programs in slums of Addis Ababa, Ethiopia. Thus, a community-based unmatched case–control study was conducted among 100 case and 200 control households that were users of shared latrines from September to November 2017 in a slum district in Addis Ababa. Cases were those who had not cleaned their shared latrines and controls were those who had cleaned their shared latrines at least once during the week prior to data collection. Data were collected using a structured questionnaire and an on-the-spot-observational checklist and analyzed using bivariate (crude odds ratio [COD]) and multivariable (adjusted odds ratio [AOR]) unconditional logistic regression model. Variables having a p-value of less than 0.25 from the bivariate logistic regression analysis were retained into multivariable analysis. From the multivariable analysis, variables with p<0.05 were declared as factors significantly associated with barriers to cleaning of shared latrines. We found that about half 99 (49.5%) of shared latrines used by cases and almost one-third 32 (32.0%) of the shared latrines used by controls had visible cracks and spaces in the floor and slabs. The barriers to cleaning of shared latrines were found to be monthly household income of less than $55.60 USD (AOR = 1.80; 95%CI: 1.2–3.10), users feeling a lack of privacy during latrine use (AOR = 2.95; 95% CI: 1.60–5.43), no locking latch on the latrine door (AOR = 4.60; 95% CI: 2.43–8.79), inadequate ventilation of latrine (AOR: 4.88; 95% CI: 2.44–9.63), lack of regular monitoring of latrine by health extension workers (AOR = 2.86; 95%CI: 1.32–6.21) and a lack of enough water at home for cleaning the latrine (AOR = 4.91; 95% CI: 1.07–9.48). This study found several barriers to cleaning of shared latrines in slums of Addis Ababa. We recommend that stakeholders promote cleaning of shared latrines by designing programs to improve latrine privacy by adding or modifying the superstructure and including a door with locking latch, to make adjustments to the structure for better ventilation, to ensure regular monitoring of latrines by health extension workers and to make enough water consistently available for regular latrine cleaning.

The Effectiveness of Betle Leaf (Piper betle L.) Extract as a Bio-pesticide for Controlled of Houseflies (Musca domestica L.)

BACKGROUND: The housefly, Musca domestica L., spreads disease by contaminating food. However, chemical insecticides used to combat houseflies can pollute the environment and can harm non-target insects and humans; this demands safer alternatives and pest control options. AIM: This study aims to evaluate the effectiveness of Piper betle L. leaf extract as a bio-pesticide against houseflies. METHODS: This study using a factorial design with six variations in concentration (0%, 5%, 10%, 15%, 20%, and 25%), four variations in contact time (15, 30, 60, and 120 minutes), and 5-day-old M. domestica adults that were bred from residential areas. RESULTS: The results show that mortality was affected by concentration (p-value < 0.000), contact time (p-value < 0.000), and the interaction between concentration and contact time (p-value = 0.0007). Of the three, concentration had the greatest effect. CONCLUSION: As such, the use of Piper betle L. extract is a suitable, cheap, and environmentally safe method for controlling M. domestica.

Zoonotic enteric parasites in Mongolian people, animals, and the environment: Using One Health to address shared pathogens

BACKGROUND

Cryptosporidium spp. and Giardia duodenalis are important zoonotic enteric pathogens of One Health concern for humans, animals, and the environment. For this study, we investigated parasite prevalence and risk factors among rural, peri-urban, and urban households and environments of Mongolia.

METHODS

This cross-sectional study implemented a household risk factor survey at 250 home sites along with sample collection from humans, animals, flies, and drinking water. Multiplex real-time PCR analysis was conducted to look for Cryptosporidium spp. and/or Giardia duodenalis within household samples.

RESULTS

Lab analysis found one or both zoonotic parasites at 20% of the participating households (51/250). Human samples had a parasite prevalence of 6.4% (27/419), domestic animals at 3.3% (19/570), pooled filth flies at 14.8% (17/115), and drinking water samples at 2% (5/250). Parasite presence at the household was significantly associated with a household's use of an improved drinking water source (OR 0.27; CI 0.12-0.61; p = < 0.01), having an indoor handwashing site (OR 0.41; CI 0.19-0.92; p = 0.03), domestic animal ownership (OR 2.40; CI 1.02-5.65; p = 0.05), and rural location (OR 0.50; CI 0.25-0.98; p = 0.04). Household use of an improved drinking water source remained significant in the multivariate model (OR 0.16; CI 0.04-0.68; p = 0.01).

CONCLUSION

In Mongolia, public and veterinary health are intertwined, particularly for rural herding households. Increased access to safe water, sanitation and hygiene infrastructure could help prevent further transmission of zoonotic enteric parasites. Public health interventions, policy and messaging should utilize a One Health framework employing joint leadership from local human and animal health sectors.

A Multi-Sectoral Approach Improves Early Child Development in a Disadvantaged Community in Peru: Role of Community Gardens, Nutrition Workshops and Enhanced Caregiver-Child Interaction: Project "Wawa Illari"

Background: Multi-dimensional monitoring evaluation and learning strategies are needed to address the complex set of factors that affect early child development in marginalized populations, but few studies have explored their effectiveness.

Objective: To compare improvement of health and development of children 0–3 years between intervention communities (IC) and control communities (CC) from peripheral settlements of Lima. Sequential interventions included: (1) home and community gardens, (2) conscious nutrition, and (3) parenting workshops following the International Child Development Program (ICDP).

Methods: Interventions were delivered by community health promoters (CHPs) using a “step-by-step” learning system. Both IC and CC were monitored before the interventions began, at 8 and 12 months (n = 113 IC and 127 CC children). Data were collected on household characteristics, diet, food security, health indicators (history of diarrhea and respiratory infections, hemoglobin, intestinal parasites, anthropometry), caregiver-child interactions and stress, and achievement of Pan-American Health Organization age-specific developmental milestones. Stepwise multiple logistic regressions were used to determine if the interventions affected food insecurity, as well as motor, social/cognitive and language delays.

Results: At baseline, 2.6% were categorized as “suspected developmental delay” and 14.2% were on “alert for development delay.” Food insecurity, diarrhea and respiratory infections were lowered following the interventions. Through the “step-by-step” approach, caregivers in IC gained skills in gardening, conscious nutrition and parenting that reduced the risk of food insecurity [Adjusted Risk Ratio = 0.20 (95% CI: 0.08–0.51)] and language delay [0.39 (0.19–0.82)] but not motor or social/cognitive delay. Use of a multiple micronutrient supplement decreased the risk of motor delay [0.12 (0.03–0.56)], but more pets were associated with higher risk of motor [3.24 (1.47–7.14)] and social/cognitive delay [2.72 (1.33–5.55)], and of food insecurity [1.73 (1.13–2.66)].

Conclusion: The combined interventions delivered by CHPs helped to mitigate the impact of adversity on food insecurity and language delay. Additional improvements may have been detected if the interventions had continued for a longer time. Our results indicate that control of infections and pets may be needed to achieve measurable results for motor and social/cognitive development. Continuous monitoring facilitated adjusting implementation strategies and achieving positive developmental outcomes.

Dynamic Model for the Epidemiology of Diarrhea and Simulation Considering Multiple Disease Carriers

Diarrhea is responsible for killing around 525,000 children every year, even though it is preventable and treatable. This research focuses on both houseflies’ roles and humans’ roles in carrying pathogens causing diarrhea as multiple disease carriers. Both human and fly compartmental models are simulated with five diseases control strategies in order to identify the epidemic dynamics. The framework considers the life cycle of flies modeled into eggs, larvae, pupae, susceptible flies, and carrier flies, while the human system follows a compartment model as susceptible, infected, recovered, and back to susceptible again (SIRS). The relationships are modeled into an ordinary differential equation-based compartmental system. Then, the control parameters of the compartmental framework are analyzed. In order to propose effective control methods, five control strategies are considered: (1) elimination of flies’ breeding site, (2) sanitation, (3) installation of UV light trap, (4) good personal and food hygiene, and (5) water purification. Then, overall, ten control scenarios using the five control strategies are analyzed. Among them, effective control solutions considering various dynamic epidemiology are provided with the simulations and analyses. The proposed framework contributes to an effective control strategy in reducing the number of both flies and infected humans, since it minimizes the spread of the disease and considers cost-effectiveness.

Water, sanitation, and hygiene risk factors of acute diarrhea among children under five years in the Gaza Strip

This cross-sectional community household-based study aims to evaluate the water, sanitation, and hygiene facilities in the Gaza Strip and to investigate their associations with the occurrence of acute diarrhea among children under five years. A survey using a structured questionnaire was conducted on 1,857 households with an child under five years from August 2017 to June 2018. About 69.7% of heads of households reported a diarrheal episode among their children during the two months preceding the survey. Multivariable logistic regression showed that sewage water observed around the households was associated with an increased risk of acute diarrhea (AOR = 2.45; P &lt; 0.001; 95% CI: 1.83–3.27). Nevertheless, the allocation of a special water tank for desalinated drinking water at home (AOR = 0.3; P = 0.02; 95% CI: 0.1–0.8), the connection of households to a closed sewerage system (AOR = 0.56; P &lt; 0.001; 95% CI: 0.43–0.73), and handwashing practices before and after eating (AOR = 0.42; P = 0.003; 95% CI: 0.24–0.74 and AOR = 0.50; P = 0.03; 95% CI: 0.26–0.94, respectively), as well as using desalinated water sources for drinking purposes, were inversely associated with the incidence of acute diarrhea among children under five. Further improvements in the existing sewerage system and the intensification of sanitation and hygiene promotion programs at the household levels may reduce the risk of acute diarrhea among children under five years in the Gaza Strip.

Associations between open drain flooding and pediatric enteric infections in the MAL-ED cohort in a low-income, urban neighborhood in Vellore, India

BACKGROUND

Open drains are common methods of transporting solid waste and excreta in low-income urban neighborhoods. Open drains can overflow due to blockages with solid waste and during rainfall, posing exposure risks. The goal of this study was to evaluate whether pediatric enteric infection was associated with open drains and flooding in a dense, low-income, urban neighborhood.

METHODS

As part of the MAL-ED study in Vellore, India, a cohort of 230 children provided stool specimens at 14-17 scheduled home visits and during diarrheal episodes in the first two years of life. All specimens were analyzed for enteric pathogens. Caregivers in 100 households reported on flooding of drains and households and monthly frequency of contact with open drains and flood water. Household GPS points were collected. Monthly rainfall totals for the Vellore district were collected from the Indian Meteorological Department. Clustering of reported drain and house flooding were identified by Kulldorff's Bernoulli Spatial Scan. Differences in enteric infection were assessed for household responses and spatial clusters, with interactions between reported flooding and rainfall to approximate monthly drain flooding retrospectively, using multivariable, mixed-effects logistic regression models.

RESULTS

Coverage of household toilets was low (33%), and most toilets (82%) discharged directly into open drains, suggesting poor neighborhood fecal sludge management. Odds of enteric infection increased significantly with total monthly rainfall for children who lived in households that reported that the nearby drain flooded (4% increase per cm of rain: OR: 1.04, 95% CI: 1.00-1.08) and for children in households in a downstream spatial cluster of reported drain flooding (5% increase per cm of rain: OR: 1.05, 95% CI: 1.01-1.09). There was no association between odds of enteric infection and frequency of reported contact with drain or floodwater.

CONCLUSIONS

Children in areas susceptible to open drain flooding had increased odds of enteric infection as rainfall increased. Results suggested that infection increased with rainfall due to neighborhood infrastructure (including poor fecal sludge management) and not frequency of contact. Thus, these exposures may not be mitigated by changes in personal behaviors alone. These results underscore the importance of improving the neighborhood environment to improve children's health in low-income, urban settings.

Fly control to prevent diarrhoea in children

BACKGROUND

Diarrhoeal disease accounts for millions of child deaths every year. Although the role of flies as vectors of infectious diarrhoea has been established, fly control is not often mentioned as an approach to decrease childhood diarrhoea. Theoretically, fly control for decreasing diarrhoea incidence can be achieved by intervening at four different levels: reduction or elimination of fly breeding sites; reduction of sources that attract houseflies; prevention of contact between flies and disease-causing organisms; and protection of people, food, and food utensils from contact with flies.

OBJECTIVES

To assess the impact of various housefly control measures on the incidence of diarrhoea and its related morbidity and mortality in children under five years of age.

SEARCH METHODS

We searched electronic databases including the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, MEDLINE, Embase, CINAHL, and LILACS, from database inception to 24 May 2018. We also searched trial registries for relevant grey literature and ongoing trials. We checked the references of the identified studies and reviews. We did not apply any filters for language, publication status (published, unpublished, in press, and ongoing), or publication date.

SELECTION CRITERIA

We planned to include randomized controlled trials (RCTs), quasi-RCTs, and controlled before-and-after studies that studied the effect of fly control on diarrhoea in children under five years of age.

DATA COLLECTION AND ANALYSIS

Two review authors extracted the data and independently assessed the risk of bias in the included study. We planned to contact study authors for additional information, where necessary. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included one cluster-RCT (491 participants) conducted in Pakistan that evaluated insecticide spraying in the first two years and baited fly traps in the third year. Insecticide spraying reduced the fly population (house index) in the intervention group during the four months of the year when both flies and cases of diarrhoea were more common, but not at other times. On average, this was associated with a reduction in the incidence of diarrhoea in the first year (illustrative mean episodes per child-year in the intervention group was 6.3 while in the control group was 7.1) and second year of the intervention (illustrative mean episodes per child‒year in the intervention group was 4.4 while in the control group was 6.5; rate ratio (RaR) 0.77, 95% confidence interval (CI) 0.67 to 0.89, low-certainty evidence). In the third year of the intervention, the baited fly traps did not demonstrate an effect on the fly population or on diarrhoea incidence (RaR 1.15, 95% CI 0.90 to 1.47, low-certainty evidence).

AUTHORS' CONCLUSIONS

The trial, conducted in a setting where there were clear seasonal peaks in fly numbers and associated diarrhoea, shows insecticide spraying may reduce diarrhoea in children. Further research on whether this finding is applicable to other setting is required, as well as work on other fly control methods, their effects, feasibility, costs, and acceptability.

The Potential Role of Synanthropic Rodents and Flies in the Transmission of Enterocytozoon bieneusi on a Dairy Cattle farm in China

Enterocytozoon bieneusi causes microsporidiosis, a condition with complex epidemiology involving both direct and indirect transmission routes. To assess the potential role of synanthropic rodents and flies in the transmission of this pathogen, a total of 277 cattle fecal samples, 199 synanthropic rodents, and 50 batches of 20 flies were collected from a cattle farm. These samples were screened for the presence of E. bieneusi by PCR and sequencing of the internal transcribed spacer (ITS) region of the rRNA gene. The positive rates of cattle, synanthropic rodents, and flies were 11.9% (33/277), 4.0% (8/199) and 12.0% (6/50), respectively. Nineteen genotypes were identified, including 11 known genotypes (BEB6, I, COS-I, EbpC, D, J, CHS5, CHG1 to CHG3 and CHG14) and eight novel genotypes (named CHC9 to CHC16). The dominant genotype detected in the present study, BEB6, was found in all three categories of hosts. Moreover, human pathogenic genotypes D and EbpC were also observed in both synanthropic rodents and flies. These results demonstrate that synanthropic rodents and flies may act as biological disseminator or mechanical vector in the transmission of microsporidiosis to humans. Efforts should be made to minimize threats from these commensal animals to public health.

Salmonella, including antibiotic-resistant Salmonella, from flies captured from cattle farms in Georgia, U.S.A

Flies can be transmission vehicles of Salmonella from cattle to humans. This study determined the prevalence of Salmonella in/on flies captured from 33 cattle farms, including 5 beef and 28 dairy farms, in Georgia, USA, and characterized antibiotic resistance profiles of the isolated Salmonella. Twenty-six out of the 33 cattle farms (79%) and 185 out of the 1650 flies (11%) tested positive for Salmonella in the study. The incidence of Salmonella-positive flies varied from farm to farm, ranging from 0 to 78%. Among the 185 Salmonella isolated from flies, 29% were resistant to ampicillin, 28% to tetracycline, 21% to amoxicillin/clavulanic acid, 20% to cefoxitin, and 12% to streptomycin. Incidences of resistance against other tested antibiotics were low, ranging from 0 to 3%. Furthermore, 28% of the Salmonella isolates were multidrug resistant, demonstrating resistance to 3 or more antibiotics. The minimal inhibitory concentrations of ampicillin, cefoxitin, streptomycin, and tetracycline against the Salmonella isolates ranged from 32 to >2048, 64 to 2048, 128 to 1024, and 32 to 1024μg/mL, respectively. These data suggest that flies could be effective vehicles of transmitting antibiotic resistant Salmonella and disseminating antibiotic resistance genes on cattle farms, posing risks to human and animal health.

Prevalence and Association of Escherichia coli and Diarrheagenic Escherichia coli in Stored Foods for Young Children and Flies Caught in the Same Households in Rural Bangladesh

Consumption of contaminated stored food can cause childhood diarrhea. Flies carry enteropathogens, although their contribution to food contamination remains unclear. We investigated the role of flies in contaminating stored food by collecting food and flies from the same households in rural Bangladesh. We selected 182 households with children ≤ 24 months old that had stored foods for later feeding at room temperature for ≥ 3 hours. We collected food samples and captured flies with fly tapes hung by the kitchen. We used the IDEXX Quanti-Tray System (Colilert-18 media; IDEXX Laboratories, Inc., Westbrook, ME) to enumerate Escherichia coli with the most probable number (MPN) method. Escherichia coli–positive IDEXX wells were analyzed by polymerase chain reaction for pathogenic E. coli genes (eae, ial, bfp, ipaH, st, lt, aat, aaiC, stx₁, and stx₂). Escherichia coli was detected in 61% (111/182) of food samples, with a mean of 1.1 log₁₀ MPN/dry g. Fifteen samples (8%) contained pathogenic E. coli; seven (4%) had enteropathogenic E. coli (EPEC) genes (eae and/or bfp); and 10 (5%) had enteroaggregative E. coli genes (aat and/or aaiC). Of flies captured in 68 (37%) households, E. coli was detected in 41 (60%, mean 2.9 log₁₀ MPN/fly), and one fly (1%) had an EPEC gene (eae). For paired fly-food samples, each log₁₀ MPN E. coli increase in flies was associated with a 0.31 log₁₀ MPN E. coli increase in stored food (95% confidence interval: 0.07, 0.55). In rural Bangladesh, flies possibly a likely route for fecal contamination of stored food. Controlling fly populations may reduce contamination of food stored for young children.

Sanitation facilities, hygienic conditions, and prevalence of acute diarrhea among under-five children in slums of Addis Ababa, Ethiopia: Baseline survey of a longitudinal study

BACKGROUND

In developing countries, children under the age of five years who live in slums are highly vulnerable to diarrhea. However, there is a paucity of information on the relationship between sanitation facilities and hygienic conditions to acute diarrhea among under-five children in slum areas of Addis Ababa, Ethiopia. Therefore, this study examines the sanitation facilities and hygienic conditions in the slums of Addis Ababa and identifies the main factors significantly associated with acute diarrhea among children aged 0-50 months in those slums.

METHODS

A community-based cross-sectional household survey was carried out between September and November 2014, that then served as the baseline survey of a longitudinal study. For this survey, 697 children aged 0-50 months were recruited from two slum districts in Addis Ababa. A pre-tested structured questionnaire and an observational checklist were used for data collection. Multivariable logistic regression analysis was used to identify sanitation facilities and hygiene-related factors that were significantly associated with acute diarrhea by controlling potential confounding effects of selected socio-demographic factors. Adjusted odds ratio (AOR) with corresponding 95% confidence interval (CI) was used to quantify the strength of association.

MAIN FINDINGS

The prevalence of acute diarrhea among children aged 0-50 months in the study area was 11.9% and 94.6% of the sanitation facilities were unimproved. Sharing of a sanitation facility by six or more households (AOR = 4.7; 95% CI: 2.4-9.4), proximity of sanitation facilities within 15 meters of homes (AOR = 6.6; 95% CI: 2.5-17.0), presence of feces (AOR = 3.9; 95% CI: 1.5-10.3) and flies (AOR = 2.5; 95% CI: 1.3-5.0) on the floor of and/or around sanitation facilities, and presence of uncollected garbage inside house compounds (AOR = 3.2; 95% CI: 1.2-8.4) were significantly associated with acute diarrhea.

CONCLUSION

This study reveals the slum environment to be high risk for diarrhea due to close proximity of sanitation facilities to homes, sharing of sanitation facilities, and poor hygiene of the sanitation facilities and housing compounds. We recommend the development of a comprehensive diarrheal disease prevention program that focuses on improving the cleanliness of the sanitation facilities and housing compounds. Increasing the number of improved sanitation facilities at an appropriate distance from houses is also essential in order to reduce the number of households that share one latrine.

The Influence of Household- and Community-Level Sanitation and Fecal Sludge Management on Urban Fecal Contamination in Households and Drains and Enteric Infection in Children

Urban sanitation necessitates management of fecal sludge inside and outside the household. This study examined associations between household sanitation, fecal contamination, and enteric infection in two low-income neighborhoods in Vellore, India. Surveys and spatial analysis assessed the presence and clustering of toilets and fecal sludge management (FSM) practices in 200 households. Fecal contamination was measured in environmental samples from 50 households and household drains. Enteric infection was assessed from stool specimens from children under 5 years of age in these households. The two neighborhoods differed significantly in toilet coverage (78% versus 33%) and spatial clustering. Overall, 49% of toilets discharged directly into open drains (“poor FSM”). Children in households with poor FSM had 3.78 times higher prevalence of enteric infection when compared with children in other households, even those without toilets. In the neighborhood with high coverage of household toilets, children in households with poor FSM had 10 times higher prevalence of enteric infection than other children in the neighborhood and drains in poor FSM clusters who had significantly higher concentrations of genogroup II norovirus. Conversely, children in households with a toilet that contained excreta in a tank onsite had 55% lower prevalence of enteric infection compared with the rest of the study area. Notably, households with a toilet in the neighborhood with low toilet coverage had more fecal contamination on floors where children played compared with those without a toilet. Overall, both toilet coverage levels and FSM were associated with environmental fecal contamination and, subsequently, enteric infection prevalence in this urban setting.

Household sanitation is associated with lower risk of bacterial and protozoal enteric infections, but not viral infections and diarrhoea, in a cohort study in a low-income urban neighbourhood in Vellore, India

Objective

This study examined associations between household sanitation and enteric infection – including diarrhoeal‐specific outcomes – in children 0–2 years of age in a low‐income, dense urban neighbourhood.

Methods

As part of the MAL‐ED study, 230 children in a low‐income, urban, Indian neighbourhood provided stool specimens at 14–17 scheduled time points and during diarrhoeal episodes in the first 2 years of life that were analysed for bacterial, parasitic (protozoa and helminths) and viral pathogens. From interviews with caregivers in 100 households, the relationship between the presence (and discharge) of household sanitation facilities and any, pathogen‐specific, and diarrhoea‐specific enteric infection was tested through mixed‐effects Poisson regression models.

Results

Few study households (33%) reported having toilets, most of which (82%) discharged into open drains. Controlling for season and household socio‐economic status, the presence of a household toilet was associated with lower risks of enteric infection (RR: 0.91, 95% CI: 0.79–1.06), bacterial infection (RR: 0.87, 95% CI: 0.75–1.02) and protozoal infection (RR: 0.64, 95% CI: 0.39–1.04), although not statistically significant, but had no association with diarrhoea (RR: 1.00, 95% CI: 0.68–1.45) or viral infections (RR: 1.12, 95% CI: 0.79–1.60). Models also suggested that the relationship between household toilets discharging to drains and enteric infection risk may vary by season.

Conclusions

The presence of a household toilet was associated with lower risk of bacterial and protozoal enteric infections, but not diarrhoea or viral infections, suggesting the health effects of sanitation may be more accurately estimated using outcome measures that account for aetiologic agents.

Adapting and Evaluating a Rapid, Low-Cost Method to Enumerate Flies in the Household Setting

Diarrhea is a leading cause of death among children under 5 years of age worldwide. Flies are important vectors of diarrheal pathogens in settings lacking networked sanitation services. There is no standardized method for measuring fly density in households; many methods are cumbersome and unvalidated. We adapted a rapid, low-cost fly enumeration technique previously developed for industrial settings, the Scudder fly grill, for field use in household settings. We evaluated its performance in comparison to a sticky tape fly trapping method at latrine and food preparation areas among households in rural Kenya. The grill method was more sensitive; it detected the presence of any flies at 80% (433/543) of sampling locations versus 64% (348/543) of locations by the sticky tape. We found poor concordance between the two methods, suggesting that standardizing protocols is important for comparison of fly densities between studies. Fly species identification was feasible with both methods; however, the sticky tape trap allowed for more nuanced identification. Both methods detected a greater presence of bottle flies near latrines compared with food preparation areas (P < 0.01). The grill method detected more flies at the food preparation area compared with near the latrine (P = 0.014) while the sticky tape method detected no difference. We recommend the Scudder grill as a sensitive fly enumeration tool that is rapid and low cost to implement.

Assessing the feasibility of fly based surveillance of wildlife infectious diseases

Monitoring wildlife infectious agents requires acquiring samples suitable for analyses, which is often logistically demanding. A possible alternative to invasive or non-invasive sampling of wild-living vertebrates is the use of vertebrate material contained in invertebrates feeding on them, their feces, or their remains. Carrion flies have been shown to contain vertebrate DNA; here we investigate whether they might also be suitable for wildlife pathogen detection. We collected 498 flies in Taï National Park, Côte d’Ivoire, a tropical rainforest and examined them for adenoviruses (family Adenoviridae), whose DNA is frequently shed in feces of local mammals. Adenoviral DNA was detected in 6/142 mammal-positive flies. Phylogenetic analyses revealed that five of these sequences were closely related to sequences obtained from local non-human primates, while the sixth sequence was closely related to a murine adenovirus. Next-generation sequencing-based DNA-profiling of the meals of the respective flies identified putative hosts that were a good fit to those suggested by adenoviral sequence affinities. We conclude that, while characterizing the genetic diversity of wildlife infectious agents through fly-based monitoring may not be cost-efficient, this method could probably be used to detect the genetic material of wildlife infectious agents causing wildlife mass mortality in pristine areas.

Quantifying tap-to-household water quality deterioration in urban communities in Vellore, India: The impact of spatial assumptions

Municipal water sources in India have been found to be highly contaminated, with further water quality deterioration occurring during household storage. Quantifying water quality deterioration requires knowledge about the exact source tap and length of water storage at the household, which is not usually known. This study presents a methodology to link source and household stored water, and explores the effects of spatial assumptions on the association between tap-to-household water quality deterioration and enteric infections in two semi-urban slums of Vellore, India. To determine a possible water source for each household sample, we paired household and tap samples collected on the same day using three spatial approaches implemented in GIS: minimum Euclidean distance; minimum network distance; and inverse network-distance weighted average. Logistic and Poisson regression models were used to determine associations between water quality deterioration and household-level characteristics, and between diarrheal cases and water quality deterioration. On average, 60% of households had higher fecal coliform concentrations in household samples than at source taps. Only the weighted average approach detected a higher risk of water quality deterioration for households that do not purify water and that have animals in the home (RR=1.50 [1.03, 2.18], p=0.033); and showed that households with water quality deterioration were more likely to report diarrheal cases (OR=3.08 [1.21, 8.18], p=0.02). Studies to assess contamination between source and household are rare due to methodological challenges and high costs associated with collecting paired samples. Our study demonstrated it is possible to derive useful spatial links between samples post hoc; and that the pairing approach affects the conclusions related to associations between enteric infections and water quality deterioration.

Assessing the impact of sanitation on indicators of fecal exposure along principal transmission pathways: A systematic review

OBJECTIVE

Fecal-oral transmission of enteric and other pathogens due to poor sanitation is a major cause of morbidity and mortality, especially in low- or middle-income settings. Few studies have investigated the impact of sanitation on indicators of transmission, a prerequisite to achieving health gains. This review attempts to summarize the literature to date.

METHODS

We searched leading databases to identify studies that address the effect of sanitation on various transmission pathways including fecal pathogens or indicator bacteria in drinking water, hand contamination, sentinel toys, food, household and latrine surfaces and soil, as well as flies and observations of human feces. This also included studies that assessed the impact of fecal contamination of water supplies based on distance from sanitation facilities. We identified 29 studies that met the review's eligibility criteria.

RESULTS AND CONCLUSION

Overall, the studies found little to no effect from sanitation interventions on these transmission pathways. There was no evidence of effects on water quality (source or household), hand or sentinel toy contamination, food contamination, or contamination of surfaces or soil. There is some evidence that sanitation was associated with reductions in flies and a small effect on observations of feces (Risk Difference -0.03, 95%CI -0.06 to 0.01). Studies show an inverse relationship between the distance of a water supply from a latrine and level of fecal contamination of such water supply. Future evaluations of sanitation interventions should include assessments of effects along transmission pathways in order to better understand the circumstances under which interventions may be effective at preventing disease.

Environmental transmission of diarrheal pathogens in low and middle income countries

Every year, more than half a million children die due to diarrheal diseases. Recent studies have identified the most important etiologies of diarrheal disease are enterotoxigenic and enteropathogenic E. coli, Shigella spp., rotavirus, norovirus and Cryptosporidium spp. These etiologies are unsurprisingly characterized by a combination of high shedding, high infectivity, and transmissibility through multiple environmental reservoirs. The relative importance of the transmission routes is likely site-specific. So the impact of interventions, which typically target only one or two environmental reservoirs, is likely also site-specific. The factors influencing the transmission routes most important for diarrheal disease are complex, including - at a minimum - etiology of endemic disease; and water, sanitation, and hygiene infrastructure and practices. The site-specific nature - and complexity of transmission - helps explain the observed variation in impacts of water, sanitation, and hygiene interventions. It may also render efforts to estimate or quantify global means for interventions' impacts irrelevant. The theme of this Perspective is that greater reductions in diarrheal disease transmission in LMICs can be achieved by designing interventions to interrupt the most important environmental transmission pathways. Intervention choice should be informed by site-specific conditions, most notably: diarrheal etiology and existing water, sanitation, and hygiene infrastructure and practices. The theme is discussed through the lens of the characteristics of the most important diarrheal diseases (shedding, infectivity, growth, and persistence) and the general characteristics of environmental reservoirs (exposure pathways and fecal contamination). The discussion highlights when interventions - and combinations of interventions - will be most effective at reducing diarrheal disease burden.

Planning for climate change: The need for mechanistic systems-based approaches to study climate change impacts on diarrheal diseases

Increased precipitation and temperature variability as well as extreme events related to climate change are predicted to affect the availability and quality of water globally. Already heavily burdened with diarrheal diseases due to poor access to water, sanitation and hygiene facilities, communities throughout the developing world lack the adaptive capacity to sufficiently respond to the additional adversity caused by climate change. Studies suggest that diarrhea rates are positively correlated with increased temperature, and show a complex relationship with precipitation. Although climate change will likely increase rates of diarrheal diseases on average, there is a poor mechanistic understanding of the underlying disease transmission processes and substantial uncertainty surrounding current estimates. This makes it difficult to recommend appropriate adaptation strategies. We review the relevant climate-related mechanisms behind transmission of diarrheal disease pathogens and argue that systems-based mechanistic approaches incorporating human, engineered and environmental components are urgently needed. We then review successful systems-based approaches used in other environmental health fields and detail one modeling framework to predict climate change impacts on diarrheal diseases and design adaptation strategies.

Prevalence of Cryptosporidium in small ruminants from Veracruz, Mexico

BACKGROUND

Cryptosporidiosis is a zoonotic disease caused by the protozoan parasite Cryptosporidium spp. that can affect domestic animal and human populations. In newborn ruminants, cryptosporidiosis is characterized by outbreaks of diarrhea, which can result in high morbidity and economic impact. The aim of the present study was to determine the prevalence of Cryptosporidium spp. in small ruminants from the Perote municipality in Veracruz State, Mexico. One hundred and sixty small ruminants (80 sheep and 80 goats) from eight farms located in four towns of the Perote municipality were examined following a cross-sectional study design. Stool samples were analyzed by a modification of the Faust centrifugation method, and the presence of Cryptosporidium spp. oocysts was examined using a modification of the Ziehl-Neelsen staining procedure. Bivariate and multivariate analyses were used to assess the association of Cryptosporidium infection and the general characteristics of the animals studied.

RESULTS

Overall, 112 (70%, 95% CI: 62.3-76.9) of the 160 small ruminants sampled were infected with Cryptosporidium spp. The prevalence of Cryptosporidium spp. infection in goats was 72.5% (95% CI: 61.4-81.9) and in sheep 67.5% (95% CI: 56.1-77.6). Small ruminants aged 1 month old had the highest (88.2%; 95% CI: 63.6-98.5) prevalence of infection. Prevalence varied from 60% to 85% among herds. Animal species, age, sex, breed, farm, town or cohabitation with cattle did not influence the prevalence of Cryptosporidium infection.

CONCLUSIONS

A high prevalence of infection with Cryptosporidium spp. was observed in small ruminants from the Perote municipality in Veracruz, Mexico. Infection was widely distributed among sheep and goats regardless of their age, breed or farm location. Further research is required to identify risk factors for, and to assess the veterinary public health significance of Cryptosporidium infection among sheep and goats in the Mexican state of Veracruz.