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Ipa M, Isnani T, Girsang VI, Amila, Harianja ES, Purba Y, Wandra T, Budke CM, Purba IE. Soil-transmitted helminth infections and anemia in children attending government run schools on Samosir Island, Indonesia. Parasite Epidemiol Control 2024; 25:e00344. [PMID: 38463546 PMCID: PMC10920706 DOI: 10.1016/j.parepi.2024.e00344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 01/20/2024] [Accepted: 02/26/2024] [Indexed: 03/12/2024] Open
Abstract
Background Worldwide, >654 million children live in regions where soil-transmitted helminth (STH) infections are endemic. These parasites cause a variety of symptoms, including anemia. Methods In May 2023, fecal and blood samples were collected from children aged 6 to 11 years attending government run (public) elementary schools in the Simanindo and Ronggur Nihuta sub-districts of Samosir Island, Indonesia where a twice a year mass drug administration (MDA) program is currently in place. A questionnaire was administered to students' parents or adult family members on possible risk factors for STH infections. Qualitative data were collected through in-depth interviews and focus group discussions. Results In total, 187 and 221 children in Simanindo and Ronggur Nihuta provided samples, respectively. The STH infection prevalence in Simanindo was 4.8% (9/187) and the infection prevalence in Ronggur Nihuta was 5.9% (13/221). In Simanindo, all infections were caused by Trichuris trichiura (n = 9), and in Ronggur Nihuta infections were caused by Ascaris lumbricoides (n = 6), Trichuris trichiura (n = 5), and A. lumbricoides + T. trichiura (n = 2). Three children had anemia but were negative for STH infections. While the results of the parent/adult questionnaires indicated access to a generally safe water supply and septic system, information from the in-depth interviews and focus groups revealed that the local water supply becomes greatly diminished during the dry season. Conclusions While MDA has been shown to effectively control roundworms and hookworms, additional measures to control trichuriasis are needed. There is also a need for the government to invest in improving the public water supply infrastructure.
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Affiliation(s)
- Mara Ipa
- Research Center for Public Health and Nutrition, National Research and Innovation Agency, Bogor, Republic of Indonesia
| | - Tri Isnani
- Research Center for Public Health and Nutrition, National Research and Innovation Agency, Bogor, Republic of Indonesia
| | | | - Amila
- Faculty of Pharmacy and Health Science, Sari Mutiara Indonesia University, Medan, Indonesia
| | | | - Yunita Purba
- Faculty of Vocational Education, Sari Mutiara Indonesia University, Medan, Indonesia
| | - Toni Wandra
- Directorate of Postgraduate, Sari Mutiara Indonesia University, Medan, Indonesia
| | - Christine M. Budke
- Department of Veterinary Integrative Biosciences, School of Veterinary Medicine & Biomedical Sciences, Texas A & M University, College Station, TX, USA
| | - Ivan Elisabeth Purba
- Directorate of Postgraduate, Sari Mutiara Indonesia University, Medan, Indonesia
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Elson L, Nyawa SM, Matharu A, Fillinger U. Developing low-cost house floors to control tungiasis in Kenya - a feasibility study. BMC Public Health 2023; 23:2483. [PMID: 38087242 PMCID: PMC10714545 DOI: 10.1186/s12889-023-17427-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 12/06/2023] [Indexed: 12/18/2023] Open
Abstract
CONTEXT Tungiasis is a neglected tropical skin disease endemic in resource-poor communities. It is caused by the penetration of the female sand flea, Tunga penetrans, into the skin causing immense pain, itching, difficulty walking, sleeping and concentrating on school or work. Infection is associated with living in a house with unsealed earthen house floors. METHODS This feasibility study used a community-based co-creation approach to develop and test simple, locally appropriate, and affordable flooring solutions to create a sealed, washable floor for the prevention of tungiasis. Locally used techniques were explored and compared in small slab trials. The floor with best strength and lowest cost was pilot trialed in 12 households with tungiasis cases to assess its durability and costs, feasibility of installation in existing local houses using local masons and explore community perceptions. Disease outcomes were measured to estimate potential impact. RESULTS It was feasible to build the capacity of a community-based organization to conduct research, develop a low-cost floor and conduct a pilot trial. The optimal low-cost floor was stabilized local subsoil with cement at a 1:9 ratio, installed as a 5 cm depth slab. A sealed floor was associated with a lower mean infection intensity among infected children than in control households (aIRR 0.53, 95%CI 0.29-0.97) when adjusted for covariates. The cost of the new floor was US$3/m2 compared to $10 for a concrete floor. Beneficiaries reported the floor made their lives much easier, enabled them to keep clean and children to do their schoolwork and eat while sitting on the floor. Challenges encountered indicate future studies would need intensive mentoring of masons to ensure the floor is properly installed and households supervised to ensure the floor is properly cured. CONCLUSION This study provided promising evidence that retrofitting simple cement-stabilised soil floors with locally available materials is a feasible option for tungiasis control and can be implemented through training of community-based organisations. Disease outcome data is promising and suggests that a definitive trial is warranted. Data generated will inform the design of a fully powered randomized trial combined with behaviour change communications. TRIAL REGISTRATION ISRCTN 62801024 (retrospective 07.07.2023).
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Affiliation(s)
- Lynne Elson
- KEMRI-Wellcome Trust, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Dabaso Tujengane CBO, Watamu, Kenya
| | | | - Abneel Matharu
- Human Health Theme, International Centre for Insect Physiology and Ecology, Nairobi, Kenya
| | - Ulrike Fillinger
- Human Health Theme, International Centre for Insect Physiology and Ecology, Nairobi, Kenya.
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Viña C, Salmo R, Pena MV, Palomero AM, Hernández JÁ, Cazapal-Monteiro C, Arias MS, Sánchez-Andrade R, Paz-Silva A. A New Comestible Formulation of Parasiticide Fungi to Reduce the Risk of Soil-Transmitted Helminth Infections in a Canine Shelter. Pathogens 2022; 11:1391. [PMID: 36422641 PMCID: PMC9698839 DOI: 10.3390/pathogens11111391] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 11/17/2022] [Accepted: 11/20/2022] [Indexed: 09/29/2023] Open
Abstract
Dogs cared for in a shelter are dewormed every three-four months, but they all become infected one-two months later by the soil-transmitted helminths (STHs) Toxocara canis, Toxascaris leonina, Trichuris vulpis, and Ancylostoma caninum. For the purpose of reducing their risk of infection by decreasing the survival of helminths' infective stages in soil, chlamydospores of two parasiticide fungi, Mucor circinelloides (ovicide) and Duddingtonia flagrans (larvicide) were formulated as handmade edible gelatins and given three days per week for 17 months to 18 dogs (DRF, dogs receiving fungi); a second group was maintained without fungi (CD, control dogs). All individuals were dewormed at months 0, 3, 7, 10 and 13, and it was observed that the levels of helminths egg-output were reduced by 96-98% fourteen days after each treatment. Fecal egg counts of STHs were similar in both groups until the 6th-8th months, and then remained significantly lower in DRF than in CD (42-100% ascarids; 30-100% trichurids and ancylostomatids). According to the results, and considering that gelatin treats have always been fully accepted, it is concluded that this new formulation offers an efficient solution to decrease the risk of infection among dogs maintained in shelters, and is therefore recommended.
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Affiliation(s)
| | | | | | | | | | - Cristiana Cazapal-Monteiro
- Control of Parasites Group (COPAR, GI-2120), Department of Animal Pathology, Faculty of Veterinary, University of Santiago de Compostela, 27002 Lugo, Spain
| | - María Sol Arias
- Control of Parasites Group (COPAR, GI-2120), Department of Animal Pathology, Faculty of Veterinary, University of Santiago de Compostela, 27002 Lugo, Spain
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4
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Capone D, Barker T, Cumming O, Flemister A, Geason R, Kim E, Knee J, Linden Y, Manga M, Meldrum M, Nala R, Smith S, Brown J. Persistent Ascaris Transmission Is Possible in Urban Areas Even Where Sanitation Coverage Is High. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:15969-15980. [PMID: 36288473 PMCID: PMC9671051 DOI: 10.1021/acs.est.2c04667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 10/13/2022] [Accepted: 10/14/2022] [Indexed: 06/16/2023]
Abstract
In low-income, urban, informal communities lacking sewerage and solid waste services, onsite sanitation (sludges, aqueous effluent) and child feces are potential sources of human fecal contamination in living environments. Working in informal communities of urban Maputo, Mozambique, we developed a quantitative, stochastic, mass-balance approach to evaluate plausible scenarios of localized contamination that could explain why the soil-transmitted helminth Ascaris remains endemic despite nearly universal coverage of latrines that sequester most fecal wastes. We used microscopy to enumerate presumptively viable Ascaris ova in feces, fecal sludges, and soils from compounds (i.e., household clusters) and then constructed a steady-state mass-balance model to evaluate possible contamination scenarios capable of explaining observed ova counts in soils. Observed Ascaris counts (mean = -0.01 log10 ova per wet gram of soil, sd = 0.71 log10) could be explained by deposits of 1.9 grams per day (10th percentile 0.04 grams, 90th percentile 84 grams) of child feces on average, rare fecal sludge contamination events that transport 17 kg every three years (10th percentile 1.0 kg, 90th percentile 260 kg), or a daily discharge of 2.7 kg aqueous effluent from an onsite system (10th percentile 0.09 kg, 90th percentile 82 kg). Results suggest that even limited intermittent flows of fecal wastes in this setting can result in a steady-state density of Ascaris ova in soils capable of sustaining transmission, given the high prevalence of Ascaris shedding by children (prevalence = 25%; mean = 3.7 log10 per wet gram, sd = 1.1 log10), the high Ascaris ova counts in fecal sludges (prevalence = 88%; mean = 1.8 log10 per wet gram, sd = 0.95 log10), and the extended persistence and viability of Ascaris ova in soils. Even near-universal coverage of onsite sanitation may allow for sustained transmission of Ascaris under these conditions.
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Affiliation(s)
- Drew Capone
- Department
of Environmental and Occupational Health, School of Public Health, Indiana University, Bloomington, Indiana47401, United States
| | - Troy Barker
- Department
of Environmental Sciences and Engineering, Gillings School of Public
Health, University of North Carolina at
Chapel Hill, Chapel
Hill, North Carolina27599, United States
| | - Oliver Cumming
- Department
of Disease Control, London School of Hygiene
and Tropical Medicine, LondonWC1E 7HT, U.K.
| | - Abeoseh Flemister
- Department
of Biology, University of North Carolina
at Chapel Hill, Chapel
Hill, North Carolina27599, United States
| | - Riley Geason
- Department
of Biology, University of North Carolina
at Chapel Hill, Chapel
Hill, North Carolina27599, United States
| | - Elizabeth Kim
- Department
of Biology, University of North Carolina
at Chapel Hill, Chapel
Hill, North Carolina27599, United States
| | - Jackie Knee
- Department
of Disease Control, London School of Hygiene
and Tropical Medicine, LondonWC1E 7HT, U.K.
| | - Yarrow Linden
- Department
of Environmental Sciences and Engineering, Gillings School of Public
Health, University of North Carolina at
Chapel Hill, Chapel
Hill, North Carolina27599, United States
| | - Musa Manga
- Department
of Environmental Sciences and Engineering, Gillings School of Public
Health, University of North Carolina at
Chapel Hill, Chapel
Hill, North Carolina27599, United States
| | - Mackenzie Meldrum
- Department
of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia30332, United States
| | - Rassul Nala
- Ministério
da Saúde, Instituto Nacional de Saúde
Maputo, Maputo1102, Mozambique
| | - Simrill Smith
- Department
of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia30332, United States
| | - Joe Brown
- Department
of Environmental Sciences and Engineering, Gillings School of Public
Health, University of North Carolina at
Chapel Hill, Chapel
Hill, North Carolina27599, United States
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Ellwanger JH, Ziliotto M, Kulmann-Leal B, Chies JAB. Iron deficiency and soil-transmitted helminth infection: classic and neglected connections. Parasitol Res 2022; 121:3381-3392. [PMID: 36258094 DOI: 10.1007/s00436-022-07697-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 10/14/2022] [Indexed: 10/24/2022]
Abstract
Beyond participating in the oxygen transport by red blood cells, iron is an essential micronutrient and contributes to different physiological pathways and processes, such as cell proliferation, DNA repair, and other homeostatic functions. Iron deficiency affects millions of people, especially children and pregnant women. The consequences of iron deficiency are diverse, including inadequate child development, impaired cognition, and reduced productivity. Several factors contribute to iron deficiency, such as iron-poor diet, genetic factors, and infection with soil-transmitted helminths (STHs), especially roundworms (Ascaris lumbricoides), hookworms (Necator americanus and Ancylostoma duodenale), and whipworms (Trichuris trichiura). This review updates and summarizes the role of STHs as drivers of iron deficiency. Also, the poorly explored connections between STH infection, geophagia (a pica manifestation), immune response, and iron deficiency are discussed, highlighting how iron deficiency may act as a risk factor for infections by STHs, in addition to being a consequence of intestinal parasitic infections. Finally, strategies for control and management of iron deficiency and STH infection are described.
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Affiliation(s)
- Joel Henrique Ellwanger
- Laboratory of Immunobiology and Immunogenetics (Prédio 43323, Laboratório 212), Department of Genetics, Postgraduate Program in Genetics and Molecular Biology (PPGBM), Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, Campus do Vale, Rio Grande do Sul, Porto Alegre, Brazil.
| | - Marina Ziliotto
- Laboratory of Immunobiology and Immunogenetics (Prédio 43323, Laboratório 212), Department of Genetics, Postgraduate Program in Genetics and Molecular Biology (PPGBM), Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, Campus do Vale, Rio Grande do Sul, Porto Alegre, Brazil
| | - Bruna Kulmann-Leal
- Laboratory of Immunobiology and Immunogenetics (Prédio 43323, Laboratório 212), Department of Genetics, Postgraduate Program in Genetics and Molecular Biology (PPGBM), Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, Campus do Vale, Rio Grande do Sul, Porto Alegre, Brazil
| | - José Artur Bogo Chies
- Laboratory of Immunobiology and Immunogenetics (Prédio 43323, Laboratório 212), Department of Genetics, Postgraduate Program in Genetics and Molecular Biology (PPGBM), Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves, 9500, Campus do Vale, Rio Grande do Sul, Porto Alegre, Brazil
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6
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do Nascimento Ramos IC, Ramos RAN, de Macedo LO, de Carvalho GA, Alves LC. The application of the FLOTAC technique for detection of helminth eggs of medical and veterinary importance in soil samples. Exp Parasitol 2022; 242:108379. [PMID: 36116521 DOI: 10.1016/j.exppara.2022.108379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 08/19/2022] [Accepted: 09/06/2022] [Indexed: 11/04/2022]
Abstract
The FLOTAC technique was initially developed to detected infective stages of parasites in animal and human feces. Recently, its applicability has been extended by the use in pastures and vegetables for human consumption. However, its use for the detection of parasites in the soil has never been investigated. In this study, we assessed the performance of the FLOTAC and compared with centrifugal flotation (CFT) and spontaneous sedimentation (SST) techniques. A total of 50 soil samples were collected from the Metropolitan region of Recife, Northeastern Brazil. Initially, samples were standardized, and then assessed in duplicate by the FLOTAC, CFT and SST. Cohen's kappa coefficient, sensitivity, specificity, positive and negative predictive values, and accuracy of the FLOTAC, CFT and SST were assessed using the results of the combination of all three techniques as gold standard. Out of all analyses performed, in 96% (48/50), helminth eggs of parasites were detected. In particular, 96% (48/50) of samples analysed through the FLOTAC technique, 76% (38/50) for CFT and 28% (14/50) for SST were positive. Nematode eggs of the Ancylostomatidae and Ascarididae families were those mostly detected in this study. Overall, the FLOTAC presented high values of sensitivity, demonstrating that this method may also be employed for detection of parasites in soil samples. This study opens new possibilities for the use of the FLOTAC technique, highlighting its role as a potential tool for detecting environmental contamination by parasites of medical and veterinary importance.
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Affiliation(s)
- Ingrid Carla do Nascimento Ramos
- Graduate Program of Animal Bioscience, Federal Rural University of Pernambuco, Recife, Brazil; Department of Veterinary Medicine, Federal Rural University of Pernambuco, Recife, Brazil
| | | | - Lucia Oliveira de Macedo
- Graduate Program of Animal Bioscience, Federal Rural University of Pernambuco, Recife, Brazil; Laboratory of Parasitology, Federal University of the Agreste of Pernambuco, Garanhuns, Brazil
| | | | - Leucio Câmara Alves
- Department of Veterinary Medicine, Federal Rural University of Pernambuco, Recife, Brazil
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Potentials and challenges in the isolation and detection of ascarid eggs in complex environmental matrices. Food Waterborne Parasitol 2022; 28:e00174. [PMID: 36017135 PMCID: PMC9396397 DOI: 10.1016/j.fawpar.2022.e00174] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 07/05/2022] [Accepted: 08/01/2022] [Indexed: 11/22/2022] Open
Abstract
Ascarid infections constitute a major concern for both human and animal health risk assessment. Although being effectively transmitted by soil, water and contaminated food, reliable detection of ascarid eggs in environmental media often remains challenging. However, contamination of the environment with ascarid ova has gained more attention as a decisive part of proper risk assessment in recent years. Due to various factors, such as sample matrices, dissociation detergents and flotation solutions, defined and standardised protocols for the isolation of eggs from complex environmental matrices are difficult to establish and therefore limited. Thus, this study reviews common techniques used for the recovery of ascarid eggs from environmental media with special emphasis on sampling strategies, purification procedures and microscopic as well as molecular detection of egg contamination. Despite various advancements, mainly in the field of molecular methods leading to more reliable and sensitive detection, it can be concluded that there is still a need for unified guidelines for sampling and recovery of ascarid eggs derived from complex environmental matrices. Standardised methods to assess environmental ascarid egg contamination are needed. The environmental sampling strategy has to be adapted to the study hypothesis. Egg detection mostly relies on matrix homogenisation, filtration, sedimentation and flotation. Microscopic detection is still frequently applied. Molecular methods enable more reliable and sensitive detection.
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Soil Contamination and Infection of School Children by Soil-Transmitted Helminths and Associated Factors at Kola Diba Primary School, Northwest Ethiopia: An Institution-Based Cross-Sectional Study. J Trop Med 2022; 2022:4561561. [PMID: 35966760 PMCID: PMC9365605 DOI: 10.1155/2022/4561561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 07/06/2022] [Indexed: 11/18/2022] Open
Abstract
Background. Soil-transmitted helminths (STHs) are among the most prevalent parasitic worms infecting humans worldwide. They are still a major public health concern in the developing world, school-age children being the most affected segment of the population. Soil polluted with parasite ova and/or infective larvae is a source of human parasitic infections. There is a substantial shift in the notion of sanitation in many countries, and control of STHs contamination in the environment is becoming an emerging topic of research. However, data are scarce on the extent of soil contamination with STHs in Ethiopia in general and the study area in particular. Objective. This study aimed to determine the prevalence of STHs in soil, and school children and associated factors at Kola Diba primary school, Northwest Ethiopia. Methods. A school-based cross-sectional study was conducted in 2020 at Kola Diba primary school. A systematic random sampling technique was used to select 400 participants. About 150 soil samples were collected. A structured Amharic version questionnaire was used to collect data on sociodemographic variables and the factors associated with STH infection. Two grams of stool specimen was processed using the Kato-Katz technique. Data were entered and analyzed using STATA version 14.1. Binary and multiple logistic regressions were performed, and
was considered statistically significant. Result. The overall prevalence of soil-transmitted helminths was 50.0% with Ascaris lumbricoides (26.2%), hookworm species (16.5%), and Trichuris trichiura (3.5%). The overall soil contamination rate was 13.3% with A. lumbricoides (9.3%) and T. trichiura (4.0%). No habit of handwashing after toilet (AOR; 2.2, 95%CI: 1.3–3.6,
value = 0.002), no habit of regular shoe-wearing (AOR; 3.7, 95%CI: 2.1–6.2,
value <0.001), untrimmed fingernail status (AOR; 4.3, 95%CI: 2.6–7.1,
value <0.001), and playing with soil (AOR; 3.5, 95%CI: 2.2–5.7,
value <0.001) were significantly associated with STHs infection. Conclusion. The prevalence of STHs remains high among primary school children, with a considerable soil contamination rate. No habit of handwashing after defecation, untrimmed fingernail status, and no habit of regular shoe-wearing and playing with soil were significantly associated with the STHs infections.
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Assessment of the nail contamination with soil-transmitted helminths in schoolchildren in Jimma Town, Ethiopia. PLoS One 2022; 17:e0268792. [PMID: 35767573 PMCID: PMC9242460 DOI: 10.1371/journal.pone.0268792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 05/08/2022] [Indexed: 11/19/2022] Open
Abstract
Background
Large-scale deworming programs have been successful in reducing the burden of disease due to soil-transmitted helminth (STH; Ascaris lumbricloides, Trichuris trichiura and hookworm) infections, but re-infection in absence of other measures is unavoidable. We assessed the role of nail contamination as a source of infection with the goal to evaluate the potential of nail clipping as a simple measure to further reduce STH-attributable morbidity.
Methods
A cross-sectional study was conducted in Jimma Town (Ethiopia). Both stool samples and clipped nails were collected from 600 schoolchildren and microscopically screened for the presence of STHs. We also interviewed the children to gain insights into their hygiene practices. Subsequently, we explored any associations between infection, nail contamination and personal hygiene.
Results
Any STH infections were observed in 24.3% of the children (A. lumbricoides: 18.5%; T. trichiura: 9.8%; hookworm: 0.5%). The intensity of the infections was mainly low, only in a few cases a moderate-to-heavy intensity infection was observed (A. lumbricoides: 4.3%; T. trichiura: 0.2%). Other helminth species observed were Schistosoma mansoni (5.0%), Hymenolepis nana (2.7%), Taenia spp. and Enterobius vermicularis (<1.0%). The analysis of the nail material revealed the presence of A. lumbricoides (1.7%), Taenia spp. (1.0%), T. trichiura (0.5%), E. vermicularis (0.5%) and H. nana (0.2%). The odds of infection with any STH increased as the frequency of trimming decreased. The odds of nail contamination with any STH and A. lumbricoides were higher for younger children.
Conclusions
The presence of helminth eggs under the nails of children highlights a poor personal hygiene. The association between any STH infection and frequency of nail trimming needs to be explored in an intervention study. The recent prevalence of any STH infections indicated that scaling down of the frequency of deworming is justified but that STH is still a public health problem.
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Tadege B, Mekonnen Z, Dana D, Sharew B, Dereje E, Loha E, Verweij JJ, Casaert S, Vlaminck J, Ayana M, Levecke B. Assessment of environmental contamination with soil-transmitted helminths life stages at school compounds, households and open markets in Jimma Town, Ethiopia. PLoS Negl Trop Dis 2022; 16:e0010307. [PMID: 35377880 PMCID: PMC9009776 DOI: 10.1371/journal.pntd.0010307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 04/14/2022] [Accepted: 03/07/2022] [Indexed: 11/19/2022] Open
Abstract
Background It remains largely unknown where and how infections with soil-transmitted helminths (STHs; Ascaris, Trichuris, Necator and Ancylostoma) occur. We therefore aimed to identify possible sources of infection by assessing the environmental contamination in an STH-endemic area. Methods We first performed a series of laboratory experiments designed to optimize a soil straining-flotation method to detect and quantify Ascaris and Trichuris eggs in soil, and to validate the diagnostic performance of the optimized method when followed by microscopy and qPCR. In a second phase, we applied this method to assess the level of STH contamination in 399 environmental samples collected from 10 school compounds, 50 households and 9 open markets in Jimma Town (Ethiopia). Subsequently, we explored associations between the environmental contamination and both the corresponding STH epidemiology at the level of the schools and the household characteristics. Finally, we assessed the knowledge, attitude and practice (KAP) towards STHs in school children. Principal findings Our soil straining-flotation method has an analytical sensitivity of 50 eggs per 100 grams of soil and egg recovery rate of 36.0% (Ascaris) and 8.0% (Trichuris). The analysis of field samples with both microscopy and qPCR revealed the presence of 8 different helminth species of medical importance, including but not limited to the human STHs. There was a significant association between the environmental contamination and prevalence of any STH infections at the school level only. The KAP indicated a lack of knowledge and awareness of STHs. Conclusions/Significance Our optimized straining-flotation method has a moderate diagnostic performance and revealed that life stages of helminths are ubiquitous in the environment, which might be due to the poor sanitary facilities at both the schools and the households, and a poor level of KAP towards STHs. Further research is required to gain more insights into the contribution of these life stages to transmission. The recent strategies to control the morbidity caused by intestinal worms have mainly been focusing on large scale deworming programs during which drugs are administered to at-risk populations. Although these large-scale deworming programs have been successful in reducing the disease burden, re-infection in the absence of other intervention measures is unavoidable. Although there is a consensus on how infections with intestinal worms are transmitted, it remains unclear where hot spots of infectious life stages can be found in endemic communities, which in turn impedes both the design and the validation of interventions that prevent (re-)infection. We optimized a laboratory method to detect life stages in soil samples and applied this method to examine soil contamination at school compounds, households and open markets in Jimma Town (Ethiopia). Finally, we assessed the household characteristics, and the knowledge, attitude, and practice towards intestinal worms among school children. Generally, our results indicated (i) a moderate performance of our laboratory method, (ii) the ubiquitous presence of life stages in the environment, (iii) a poor level of sanitary facilities at both the schools and the households and (iv) a poor level of knowledge, attitude and practices towards intestinal worms.
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Affiliation(s)
- Bamlaku Tadege
- School of Medicine, Hawassa University, Hawassa, Ethiopia
- School of Medical Laboratory Sciences, Jimma University, Jimma, Ethiopia
- Department of Translational Physiology, Infectiology and Public Health, Ghent University, Merelbeke, Belgium
- * E-mail: (BT); (BL)
| | - Zeleke Mekonnen
- School of Medical Laboratory Sciences, Jimma University, Jimma, Ethiopia
- Molecular Biology and NTDs Research Center, Jimma University, Jimma, Ethiopia
| | - Daniel Dana
- School of Medical Laboratory Sciences, Jimma University, Jimma, Ethiopia
- Molecular Biology and NTDs Research Center, Jimma University, Jimma, Ethiopia
| | - Bizuwarek Sharew
- School of Medical Laboratory Sciences, Jimma University, Jimma, Ethiopia
| | - Eden Dereje
- Molecular Biology and NTDs Research Center, Jimma University, Jimma, Ethiopia
| | - Eskindir Loha
- Chr. Michelsen Institute, Bergen, Norway
- Centre for International Health, University of Bergen, Bergen, Norway
| | - Jaco J. Verweij
- Microvida, Laboratory for Medical Microbiology and Immunology, Elisabeth-TweeSteden Hospital, Tilburg, The Netherlands
| | - Stijn Casaert
- Department of Translational Physiology, Infectiology and Public Health, Ghent University, Merelbeke, Belgium
| | - Johnny Vlaminck
- Department of Translational Physiology, Infectiology and Public Health, Ghent University, Merelbeke, Belgium
| | - Mio Ayana
- School of Medical Laboratory Sciences, Jimma University, Jimma, Ethiopia
- Department of Translational Physiology, Infectiology and Public Health, Ghent University, Merelbeke, Belgium
- Molecular Biology and NTDs Research Center, Jimma University, Jimma, Ethiopia
| | - Bruno Levecke
- Department of Translational Physiology, Infectiology and Public Health, Ghent University, Merelbeke, Belgium
- * E-mail: (BT); (BL)
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11
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Getachew M, Yeshigeta R, Tiruneh A, Alemu Y, Dereje E, Mekonnen Z. Soil-Transmitted Helminthic Infections and Geophagia among Pregnant Women in Jimma Town Health Institutions, Southwest Ethiopia. Ethiop J Health Sci 2021; 31:1033-1042. [PMID: 35221621 PMCID: PMC8843140 DOI: 10.4314/ejhs.v31i5.16] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Accepted: 07/07/2021] [Indexed: 12/19/2022] Open
Abstract
Background Pregnancy is a key step for human's reproduction and continuity of generation. Pregnant women are among at risk groups for the infection of soil-transmitted helminths (STHs). STHs are highly prevalent in low- and middle-income countries due to the deprived environmental sanitation and personal hygiene. Eating soil (geophagia) is also commonly practiced by pregnant women, particularly in developing countries. The aim of this study was to determine the prevalence of STHs and geophagia, and to assess associated factors among pregnant women in Jimma, Southwest Ethiopia. Methods A cross sectional study was conducted among 407 pregnant women attending antenatal care (ANC) at different health facilities located in Jimma Town. Data related to sociodemographic and geophagia practice was collected using a structured questionnaire and STH infections status was determined by using McMaster technique. Results A total of 407 pregnant women were included in this study. The overall prevalence of any STHs was 19.7% (80/407). Ascaris lumbricoides was the most prevalent 45(56.2%), followed by Trichuris trichiura 19(23.8%) and hookworms 12(15%). There were 4(5%) of double infection with A. lumbricoides and T. trichiura. Overall, 71 (17.4%) of the pregnant women responded to practice geophagia. STHs infection was significantly higher among geophagic pregnant women (p<0.01) and pregnant women who practiced geophagia were 3 times more likely (OR 2.9, 95% CI 1.3–4.2) to have the STHs compared to non-geophagic. Out of those who claimed soil eating habits, 59.1% preferred reddish soil type. Geophagia practice was significantly higher during the third trimester as compared to first and second (p<0.05). Conclusion Geophagia is a risky behavior and this study showed a significant association of geophagia practice with STH infections, although the causal relation could not be established.
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Affiliation(s)
| | - Ruth Yeshigeta
- School of Medical Laboratory Sciences, Institute of Health, Jimma University
| | - Abebaw Tiruneh
- School of Medical Laboratory Sciences, Institute of Health, Jimma University
| | - Yonas Alemu
- School of Medical Laboratory Sciences, Institute of Health, Jimma University
| | - Eden Dereje
- Molecular Biology Research Center, Jimma University
| | - Zeleke Mekonnen
- School of Medical Laboratory Sciences, Institute of Health, Jimma University
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12
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Capone D, Berendes D, Cumming O, Holcomb D, Knee J, Konstantinidis KT, Levy K, Nalá R, Risk BB, Stewart J, Brown J. Impact of an Urban Sanitation Intervention on Enteric Pathogen Detection in Soils. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:9989-10000. [PMID: 34236178 PMCID: PMC8327413 DOI: 10.1021/acs.est.1c02168] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
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 (preintervention) and after 24 months (postintervention) as part of the Maputo Sanitation Trial. We tested soils for the presence of nucleic acids associated with 18 enteric pathogens using a multiplex reverse transcription qPCR platform. We detected at least one pathogen-associated gene target in 91% (163/179) of soils and a median of 3 (IQR = 1, 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 detecting ≥1 pathogen gene by 15% (adjusted prevalence ratio, aPR = 0.85; 95% CI: 0.70, 1.0) and the total number of pathogens 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.
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Affiliation(s)
- Drew Capone
- Department of Environmental Sciences and Engineering, Gillings School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - David Berendes
- Waterborne Disease Prevention Branch, Division of Foodborne, Waterborne, and Environmental Diseases, National Center for Emerging Zoonotic and Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Oliver Cumming
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - David Holcomb
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Jackie Knee
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Konstantinos T. Konstantinidis
- Civil and Environmental Engineering, Georgia Institute of Technology, 311 Ferst Drive, Atlanta, Georgia, United States of America
| | - Karen Levy
- Environmental and Occupational Health Sciences, University of Washington, 2980 15th Ave NE, Seattle, Washington, United States of America
| | - Rassul Nalá
- Ministério da Saúde, Instituto Nacional de Saúde Maputo, Maputo, Mozambique
| | - Benjamin B. Risk
- Department of Biostatistics and Bioinformatics, Emory University, Atlanta, Georgia, United States of America
| | - Jill Stewart
- Department of Environmental Sciences and Engineering, Gillings School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Joe Brown
- Department of Environmental Sciences and Engineering, Gillings School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
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13
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Kwong LH, Sen D, Islam S, Shahriar S, Benjamin-Chung J, Arnold BF, Hubbard A, Parvez SM, Islam M, Unicomb L, Rahman MM, Nelson K, Colford JM, Luby SP, Ercumen A. Effect of sanitation improvements on soil-transmitted helminth eggs in courtyard soil from rural Bangladesh: Evidence from a cluster-randomized controlled trial. PLoS Negl Trop Dis 2021; 15:e0008815. [PMID: 34319986 PMCID: PMC8351931 DOI: 10.1371/journal.pntd.0008815] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 08/09/2021] [Accepted: 06/24/2021] [Indexed: 11/19/2022] Open
Abstract
Improved sanitation has been hypothesized to reduce soil-transmitted helminth (STH) infections by reducing the prevalence and concentration of STH eggs/larvae in soil. We evaluated the effect of a randomized sanitation program (providing households with an improved dual-pit latrine, tools for child/animal feces management, and behavioral messaging) on reducing the prevalence and concentration of STH eggs in soil from household courtyards. We collected soil samples from 1405 households enrolled in the sanitation intervention (n = 419) and control (n = 914) groups of a cluster-randomized controlled trial (WASH Benefits) in rural Bangladesh approximately 2 years after the initiation of the interventions. We analyzed samples for Ascaris lumbricoides, Trichuris trichiura, and hookworm eggs by microscopy. We estimated prevalence ratios (PR) and egg count ratio (ECR) to compare the prevalence of STH eggs and arithmetic and geometric mean egg counts for STH eggs per gram of soil in the sanitation and control arms. Among intervention households, latrines achieved high and sustained user uptake by adults while child open defecation remained common and most households did not dispose of child feces hygienically. In courtyard soil from control households, the prevalence of any STH eggs was 75.7% and the prevalence of any larvated STH eggs was 67.3%. A. lumbricoides was detected in 63.0% of control samples and T. trichiura in 55.7% of control samples; hookworm was not detected in any sample. In the control arm, the arithmetic mean egg count for any STH was 3.96 eggs/dry gram, while the geometric mean was 1.58 eggs/dry gram. There was no difference between the intervention and control groups in the prevalence of any STH eggs (PR = 0.98 (95% CI: 0.91, 1.05)) or mean egg counts (ECR = 0.08 (95% CI: -0.10, 0.26) for geometric mean and 0.07 (95% CI: -0.22, 0.37) for arithmetic mean). Adjusted models gave similar results. A compound-level sanitation intervention that provided improved latrines and tools for disposal of child and animal feces did not have an impact on STH eggs in soil. In order to effectively reduce the prevalence and concentration of STH eggs in the environment, sustained, widespread use of sanitation strategies to isolate and hygienically dispose of child and animal feces may need to complement traditional strategies for containment of adult human feces. Trial Registration: NCT01590095.
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Affiliation(s)
- Laura H. Kwong
- Woods Institute for the Environment, Stanford University, Stanford, California, United States of America
| | - Debashis Sen
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Sharmin Islam
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Sunny Shahriar
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Jade Benjamin-Chung
- School of Public Health, University of California, Berkeley, California, United States of America
| | - Benjamin F. Arnold
- Francis I. Proctor Foundation, University of California, San Francisco, San Francisco, California, United States of America
| | - Alan Hubbard
- School of Public Health, University of California, Berkeley, California, United States of America
| | - Sarker Masud Parvez
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Mahfuza Islam
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Leanne Unicomb
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Md. Mahbubur Rahman
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Kara Nelson
- Department of Civil Engineering, University of California, Berkeley, California, United States of America
| | - John M. Colford
- School of Public Health, University of California, Berkeley, California, United States of America
| | - Stephen P. Luby
- Woods Institute for the Environment, Stanford University, Stanford, California, United States of America
| | - Ayse Ercumen
- Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, North Carolina, United States of America
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14
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Sack A, Palanisamy G, Manuel M, Paulsamy C, Rose A, Kaliappan SP, Ward H, Walson JL, Halliday KE, Ajjampur SSR. A One Health Approach to Defining Animal and Human Helminth Exposure Risks in a Tribal Village in Southern India. Am J Trop Med Hyg 2021; 105:196-203. [PMID: 34029209 PMCID: PMC8274781 DOI: 10.4269/ajtmh.20-1476] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 02/11/2021] [Indexed: 11/07/2022] Open
Abstract
The high burden of soil-transmitted helminth infections has been studied in India; however, little data exist on zoonotic helminths, and on animal-associated exposure to soil-transmitted helminths. Our study took place in the Jawadhu Hills, which is a tribal region in Tamil Nadu, India. Using a One Health approach, we included animal and environmental samples and human risk factors to answer questions about the associations among infected household soil, domestic animals, and human risk factors. Helminth eggs were identified by microscopy in animal and soil samples, and a survey about risk factors was administered to the head of the household. Contact with animals was reported in 71% of households. High levels of helminth infections were found across domestic animal species, especially in goats, chickens, and dogs. Helminth eggs were recorded in 44% of household soil (n = 43/97) and separately in 88% of soil near a water source (n = 28/32). Animal contact was associated with 4.05 higher odds of having helminth eggs in the household soil (P = 0.01), and also having a water source at the household was associated with a 0.33 lower odds of having helminth eggs in the household soil (P = 0.04). Soil moisture was a mediator of this association with a significant indirect effect (P < 0.001). The proportion mediated was 0.50. While our work does not examine transmission, these results support consideration of animal-associated exposure to STH and potentially zoonotic helminths in future interventions to reduce helminth burden. Our study provides support for further investigation of the effects of animals and animal fecal matter on human health.
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Affiliation(s)
- Alexandra Sack
- Clinical and Translational Science Graduate Program, Tufts University Graduate School of Biomedical Sciences, Boston, Massachusetts
| | - Gokila Palanisamy
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, Tamil Nadu, India
| | - Malathi Manuel
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, Tamil Nadu, India
| | - Chinnaduraipandi Paulsamy
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, Tamil Nadu, India
| | - Anuradha Rose
- Department of Community Medicine, Christian Medical College, Vellore, Tamil Nadu, India
| | | | - Honorine Ward
- Division of Geographic Medicine and Infectious Diseases, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts
| | - Judd L. Walson
- Departments of Global Health, Medicine (Infectious Disease), Pediatrics and Epidemiology, University of Washington, Seattle, Washington
- The DeWorm3 Project, University of Washington, Seattle, Washington
| | - Katherine E. Halliday
- Departments of Global Health, Medicine (Infectious Disease), Pediatrics and Epidemiology, University of Washington, Seattle, Washington
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Sitara Swarna Rao Ajjampur
- The Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, Tamil Nadu, India
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15
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Spatial scales in human movement between reservoirs of infection. J Theor Biol 2021; 524:110726. [PMID: 33895180 PMCID: PMC8204271 DOI: 10.1016/j.jtbi.2021.110726] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 04/09/2021] [Accepted: 04/12/2021] [Indexed: 11/22/2022]
Abstract
Simple, yet flexible, model of human movement patterns. Analytic formalism which can be used to derive important spatial scales. Introduces a novel drift–diffusion approximation for stochastic reservoirs. A new critical spatial scale predicted for helminth reservoirs of infection. The necessary data needed to test these predictions is outlined in detail.
The life cycle of parasitic organisms that are the cause of much morbidity in humans often depend on reservoirs of infection for transmission into their hosts. Understanding the daily, monthly and yearly movement patterns of individuals between reservoirs is therefore of great importance to implementers of control policies seeking to eliminate various parasitic diseases as a public health problem. This is due to the fact that the underlying spatial extent of the reservoir of infection, which drives transmission, can be strongly affected by inputs from external sources, i.e., individuals who are not spatially attributed to the region defined by the reservoir itself can still migrate and contribute to it. In order to study the importance of these effects, we build and examine a novel theoretical model of human movement between spatially-distributed focal points for infection clustered into regions defined as ‘reservoirs of infection’. Using our model, we vary the spatial scale of human moment defined around focal points and explicitly calculate how varying this definition can influence the temporal stability of the effective transmission dynamics – an effect which should strongly influence how control measures, e.g., mass drug administration (MDA), define evaluation units (EUs). Considering the helminth parasites as our main example, by varying the spatial scale of human movement, we demonstrate that a critical scale exists around infectious focal points at which the migration rate into their associated reservoir can be neglected for practical purposes. This scale varies by species and geographic region, but is generalisable as a concept to infectious reservoirs of varying spatial extents and shapes. Our model is designed to be applicable to a very general pattern of infectious disease transmission modified by the migration of infected individuals between clustered communities. In particular, it may be readily used to study the spatial structure of hosts for macroparasites with temporally stationary distributions of infectious focal point locations over the timescales of interest, which is viable for the soil-transmitted helminths and schistosomes. Additional developments will be necessary to consider diseases with moving reservoirs, such as vector-born filarial worm diseases.
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16
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Benjamin-Chung J, Crider YS, Mertens A, Ercumen A, Pickering AJ, Lin A, Steinbaum L, Swarthout J, Rahman M, Parvez SM, Haque R, Njenga SM, Kihara J, Null C, Luby SP, Colford JM, Arnold BF. Household finished flooring and soil-transmitted helminth and Giardia infections among children in rural Bangladesh and Kenya: a prospective cohort study. Lancet Glob Health 2021; 9:e301-e308. [PMID: 33607029 PMCID: PMC7900607 DOI: 10.1016/s2214-109x(20)30523-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 11/20/2020] [Accepted: 11/30/2020] [Indexed: 12/31/2022]
Abstract
BACKGROUND Soil-transmitted helminths and Giardia duodenalis are responsible for a large burden of disease globally. In low-resource settings, household finished floors (eg, concrete floors) might reduce transmission of soil-transmitted helminths and G duodenalis. METHODS In a prospective cohort of children nested within two randomised trials in rural Bangladesh and Kenya, we estimated associations between household finished flooring and soil-transmitted helminths and G duodenalis prevalence. In 2015-16, we collected stool samples from children aged 2-16 years in rural Bangladesh and Kenya. We detected soil-transmitted helminth infection using quantitative PCR (qPCR; Bangladesh n=2800; Kenya n=3094), and G duodenalis using qPCR in Bangladesh (n=6894) and ELISA in Kenya (n=8899). We estimated adjusted prevalence ratios (aPRs) using log-linear models adjusted for potential confounders. FINDINGS 7187 (92·2%) of 7795 children in Bangladesh and 9077 (93·7%) of 9686 children in Kenya provided stool specimens that were analysed by qPCR. At enrolment, 691 (10%) households in Bangladesh and 471 (5%) households in Kenya had finished floors. In both countries, household finished flooring was associated with lower Ascaris lumbricoides prevalence (Bangladesh aPR 0·33, 95% CI 0·14-0·78; Kenya 0·62, 0·39-0·98) and any soil-transmitted helminths (Bangladesh 0·73, 0·52-1·01; Kenya 0·57, 0·37-0·88). Household finished floors were also associated with lower Necator americanus prevalence in Bangladesh (0·52, 0·29-0·94) and G duodenalis prevalence in both countries (Bangladesh 0·78, 0·64-0·95; Kenya 0·82, 0·70-0·97). INTERPRETATION In low-resource settings, living in households with finished floors over a 2-year period was associated with lower prevalence of G duodenalis and some soil-transmitted helminths in children. FUNDING Bill & Melinda Gates Foundation and Task Force for Global Health.
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Affiliation(s)
- Jade Benjamin-Chung
- Division of Epidemiology & Biostatistics, University of California, Berkeley, Berkeley, CA, USA.
| | - Yoshika S Crider
- Division of Epidemiology & Biostatistics, University of California, Berkeley, Berkeley, CA, USA; Energy & Resources Group, University of California, Berkeley, Berkeley, CA, USA
| | - Andrew Mertens
- Division of Epidemiology & Biostatistics, University of California, Berkeley, Berkeley, CA, USA
| | - Ayse Ercumen
- Department of Forestry and Environmental Resources, North Carolina State University, Raleigh, NC, USA
| | - Amy J Pickering
- Civil and Environmental Engineering, Tufts University, Medford, MA, USA
| | - Audrie Lin
- Division of Epidemiology & Biostatistics, University of California, Berkeley, Berkeley, CA, USA
| | | | - Jenna Swarthout
- Civil and Environmental Engineering, Tufts University, Medford, MA, USA
| | - Mahbubur Rahman
- International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
| | - Sarker M Parvez
- International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
| | - Rashidul Haque
- International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
| | - Sammy M Njenga
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya
| | - Jimmy Kihara
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya
| | - Clair Null
- Center for International Policy Research and Evaluation, Mathematica Policy Research, Washington, DC, USA
| | - Stephen P Luby
- Division of Infectious Diseases and Geographic Medicine, Stanford University, Stanford, CA, USA
| | - John M Colford
- Division of Epidemiology & Biostatistics, University of California, Berkeley, Berkeley, CA, USA
| | - Benjamin F Arnold
- Francis I Proctor Foundation, University of California, San Francisco, CA, USA; Department of Ophthalmology, University of California, San Francisco, CA, USA
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17
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Goddard FB, Ban R, Barr DB, Brown J, Cannon J, Colford JM, Eisenberg JNS, Ercumen A, Petach H, Freeman MC, Levy K, Luby SP, Moe C, Pickering AJ, Sarnat JA, Stewart J, Thomas E, Taniuchi M, Clasen T. Measuring Environmental Exposure to Enteric Pathogens in Low-Income Settings: Review and Recommendations of an Interdisciplinary Working Group. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:11673-11691. [PMID: 32813503 PMCID: PMC7547864 DOI: 10.1021/acs.est.0c02421] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 08/18/2020] [Accepted: 08/19/2020] [Indexed: 05/06/2023]
Abstract
Infections with enteric pathogens impose a heavy disease burden, especially among young children in low-income countries. Recent findings from randomized controlled trials of water, sanitation, and hygiene interventions have raised questions about current methods for assessing environmental exposure to enteric pathogens. Approaches for estimating sources and doses of exposure suffer from a number of shortcomings, including reliance on imperfect indicators of fecal contamination instead of actual pathogens and estimating exposure indirectly from imprecise measurements of pathogens in the environment and human interaction therewith. These shortcomings limit the potential for effective surveillance of exposures, identification of important sources and modes of transmission, and evaluation of the effectiveness of interventions. In this review, we summarize current and emerging approaches used to characterize enteric pathogen hazards in different environmental media as well as human interaction with those media (external measures of exposure), and review methods that measure human infection with enteric pathogens as a proxy for past exposure (internal measures of exposure). We draw from lessons learned in other areas of environmental health to highlight how external and internal measures of exposure can be used to more comprehensively assess exposure. We conclude by recommending strategies for advancing enteric pathogen exposure assessments.
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Affiliation(s)
- Frederick
G. B. Goddard
- Gangarosa
Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, United States
| | - Radu Ban
- Bill and
Melinda Gates Foundation, Seattle, Washington 98109, United States
| | - Dana Boyd Barr
- Gangarosa
Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, United States
| | - Joe Brown
- School of
Civil and Environmental Engineering, Georgia
Institute of Technology, Atlanta, Georgia 30332, United States
| | - Jennifer Cannon
- Centers
for Disease Control and Prevention Foundation, Atlanta, Georgia 30308, United States
| | - John M. Colford
- Division
of Epidemiology and Biostatistics, School of Public Health, University of California−Berkeley, Berkeley, California 94720, United States
| | - Joseph N. S. Eisenberg
- Department
of Epidemiology, University of Michigan
School of Public Health, Ann Arbor, Michigan 48109, United States
| | - Ayse Ercumen
- Department
of Forestry and Environmental Resources, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Helen Petach
- U.S. Agency
for International Development, Washington, DC 20004, United States
| | - Matthew C. Freeman
- Gangarosa
Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, United States
| | - Karen Levy
- Department
of Environmental and Occupational Health Sciences, University of Washington, Seattle, Washington 98105, United States
| | - Stephen P. Luby
- Division
of Infectious Diseases and Geographic Medicine, Stanford University, California 94305, United States
| | - Christine Moe
- Center
for
Global Safe Water, Sanitation and Hygiene, Rollins School of Public
Health, Emory University, Atlanta, Georgia 30322, United States
| | - Amy J. Pickering
- Department
of Civil and Environmental Engineering, School of Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Jeremy A. Sarnat
- Gangarosa
Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, United States
| | - Jill Stewart
- Department
of Environmental Sciences and Engineering, Gillings School of Global
Public Health, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Evan Thomas
- Mortenson
Center in Global Engineering, University
of Colorado Boulder, Boulder, Colorado 80303, United States
| | - Mami Taniuchi
- Division
of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia 22903, United States
| | - Thomas Clasen
- Gangarosa
Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, United States
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18
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Mejia R, Seco-Hidalgo V, Garcia-Ramon D, Calderón E, Lopez A, Cooper PJ. Detection of enteric parasite DNA in household and bed dust samples: potential for infection transmission. Parasit Vectors 2020; 13:141. [PMID: 32188497 PMCID: PMC7079405 DOI: 10.1186/s13071-020-04012-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 03/10/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Enteric parasites are transmitted in households but few studies have sampled inside households for parasites and none have used sensitive molecular methods. METHODS We collected bed and living room dust samples from households of children participating in a clinical trial of anthelmintic treatment in rural coastal Ecuador. Dust was examined for presence of DNA specific for 11 enteric parasites (Ascaris lumbricoides, Trichuris trichiura, Ancylostoma duodenale, Necator americanus, Strongyloides stercoralis, Toxocara canis and T. cati, Giardia lamblia, Blastocystis hominis, Cryptosporidium spp., and Entamoeba histolytica) by quantitative PCR (qPCR). RESULTS Of the 38 households sampled, 37 had positive dust for at least one parasite and up to 8 parasites were detected in single samples. Positivity was greatest for B. hominis (79% of household samples) indicating a high level of environmental fecal contamination. Dust positivity rates for individual pathogens were: S. stercoralis (52%), A. lumbricoides (39%), G. lamblia (39%), Toxocara spp. (42%), hookworm (18%) and T. trichiura (8%). DNA for Cryptosporidium spp. and E. histolytica was not detected. Bed dust was more frequently positive than floor samples for all parasites detected. Positivity for A. lumbricoides DNA in bed (adjusted OR: 10.0, 95% CI: 2.0-50.1) but not floor dust (adjusted OR: 3.6, 95% CI: 0.3-37.9) was significantly associated with active infections in children. CONCLUSIONS To our knowledge, this is the first use of qPCR on environmental samples to detect a wide range of enteric pathogen DNA. Our results indicate widespread contamination of households with parasite DNA and raise the possibility that beds, under conditions of overcrowding in a humid tropical setting, may be a source of transmission.
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Affiliation(s)
- Rojelio Mejia
- National School of Tropical Medicine, Baylor College of Medicine, Texas, USA.,School of Medicine, Universidad Internacional del Ecuador, Quito, Ecuador
| | | | - Diana Garcia-Ramon
- School of Medicine, Universidad Internacional del Ecuador, Quito, Ecuador
| | - Evelyn Calderón
- School of Medicine, Universidad Internacional del Ecuador, Quito, Ecuador
| | - Andrea Lopez
- School of Medicine, Universidad Internacional del Ecuador, Quito, Ecuador
| | - Philip J Cooper
- School of Medicine, Universidad Internacional del Ecuador, Quito, Ecuador. .,Institute of Infection and Immunity, St George's University of London, London, UK.
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Chidziwisano K, Slekiene J, Kumwenda S, Mosler HJ, Morse T. Toward Complementary Food Hygiene Practices among Child Caregivers in Rural Malawi. Am J Trop Med Hyg 2020; 101:294-303. [PMID: 31237230 PMCID: PMC6685574 DOI: 10.4269/ajtmh.18-0639] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Despite being preventable, foodborne diseases remain a global health challenge. Poor food hygiene practices such as improper handling of kitchen utensils are among the major causes of diarrhea transmission. A formative study was conducted in Malawi to inform an intervention design to promote complementary food hygiene practices. An assessment of contextual and psychosocial factors for behavior change was conducted using Risk, Attitude, Norms, Ability, and Self-regulation model. We conducted 323 household surveys with caregivers of children aged 6 to 24 months. Analysis of variance was used to estimate difference between doers and non-doers of three targeted behaviors: washing utensils with soap, keeping utensils on a raised place, and handwashing with soap. Analysis of variance analyses revealed that literacy level, ownership of animals, and presence of handwashing facility and dish racks were contextual factors predicting storage of utensils on an elevated place and handwashing frequencies. Psychosocial factors, such as time spent to wash utensils with soap, distance to the handwashing facility, and cost for soap, had an influence on washing utensils and handwashing practices. Perceived vulnerability determined effective handwashing and storage of utensils. Perceived social norms and ability estimates were favorable for the three targeted behaviors. Promotion of already existing targeted beneficial behaviors should be encouraged among caregivers. Risk perceptions on storage of utensils and handwashing practices should be increased with motivational exercises such as paint games. Caregivers' technical know-how of local dish rack and tippy tap construction is essential.
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Affiliation(s)
- Kondwani Chidziwisano
- Department of Environmental Health and WASHTED Centre, Polytechnic, University of Malawi, Blantyre, Malawi.,Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, Scotland
| | - Jurgita Slekiene
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
| | - Save Kumwenda
- Department of Environmental Health and WASHTED Centre, Polytechnic, University of Malawi, Blantyre, Malawi
| | - Hans-Joachim Mosler
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland
| | - Tracy Morse
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, Scotland.,Department of Environmental Health and WASHTED Centre, Polytechnic, University of Malawi, Blantyre, Malawi
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20
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Isaac C, Turay PN, Inegbenosun CU, Ezekiel SA, Adamu HO, Ohiolei JA. Prevalence of Soil-transmitted Helminths in Primary School Playgrounds in Edo State, Southern Nigeria. Helminthologia 2019; 56:282-295. [PMID: 31708668 PMCID: PMC6818638 DOI: 10.2478/helm-2019-0028] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 07/31/2019] [Indexed: 12/20/2022] Open
Abstract
Schoolchildren in primary schools are mostly at risk of acquiring soil-transmitted helminths (STHs) infections due to their habits (geophagy, onychophagy and playing with barefoot). Profiling soil parasites on school playgrounds is expected to provide an insight to an array of parasites schoolchildren are constantly at risk of acquiring; and this information could guide on intervention programmes. Soil samples from sixteen primary school playgrounds in Edo State (South-South, Nigeria) were collected over a six-month period both in the dry (January, February and March) and wet (May, June and July) seasons in 2018 and early 2019. Samples were processed and analysed following standard parasitological procedures. Of the 576 soil samples collected, 318(55.2 %) were positive with one or more soil parasites. Generally, the predominant parasites recovered from the total number of soil samples collected were: Ascaris 127(22 %), Strongyloides 111(19.27 %) and hookworm 50(8.68 %). Ascaris was most preponderant in the dry season, while Strongyloides was the most occurring in the wet season. The mean differences in the parasite load for Ascaris and hookworm between dry and wet seasons were not significant; while for Strongyloides it was higher in the wet than dry season. These results could be a consequence of observed poor state of toilet/sanitary facilities as well as the lack or poor state of basic infrastructure like proper drainage and waste disposal systems in the host communities. There is therefore urgent need to interrupt the STHs transmission cycles in the environment and possibly in schoolchildren by instituting sustainable intervention programmes within schools located in STHs endemic regions like southern Nigeria.
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Affiliation(s)
- C. Isaac
- Department of Zoology, Faculty of Life Sciences, Ambrose Alli University, Ekpoma, Nigeria
| | - P. N. Turay
- Department of Zoology, Faculty of Life Sciences, Ambrose Alli University, Ekpoma, Nigeria
| | - C. U. Inegbenosun
- Department of Zoology, Faculty of Life Sciences, Ambrose Alli University, Ekpoma, Nigeria
| | - S. A. Ezekiel
- Department of Zoology, Faculty of Life Sciences, Ambrose Alli University, Ekpoma, Nigeria
| | - H. O. Adamu
- Department of Zoology, Faculty of Life Sciences, Ambrose Alli University, Ekpoma, Nigeria
| | - J. A. Ohiolei
- Department of Zoology, Faculty of Life Sciences, Ambrose Alli University, Ekpoma, Nigeria
- State Key Laboratory of Veterinary Etiological Biology/Key Laboratory of Veterinary Parasitology of Gansu Province/Key Laboratory of Zoonoses of Agriculture Ministry/Lanzhou Veterinary Research Institute, CAAS, Lanzhou730046, P. R. China
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Targeting a highly repeated germline DNA sequence for improved real-time PCR-based detection of Ascaris infection in human stool. PLoS Negl Trop Dis 2019; 13:e0007593. [PMID: 31329586 PMCID: PMC6675119 DOI: 10.1371/journal.pntd.0007593] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 08/01/2019] [Accepted: 07/01/2019] [Indexed: 12/13/2022] Open
Abstract
Background With the expansion of soil transmitted helminth (STH) intervention efforts and the corresponding decline in infection prevalence, there is an increased need for sensitive and specific STH diagnostic assays. Previously, through next generation sequencing (NGS)-based identification and targeting of non-coding, high copy-number repetitive DNA sequences, we described the development of a panel of improved quantitative real-time PCR (qPCR)-based assays for the detection of Necator americanus, Ancylostoma duodenale, Ancylostoma ceylanicum, Trichuris trichiura, and Strongyloides stercoralis. However, due to the phenomenon of chromosome diminution, a similar assay based on high copy-number repetitive DNA was not developed for the detection of Ascaris lumbricoides. Recently, the publication of a reference-level germline genome sequence for A. lumbricoides has facilitated our development of an improved assay for this human pathogen of vast global importance. Methodology/Principal findings Repurposing raw DNA sequence reads from a previously published Illumina-generated, NGS-based A. lumbricoides germline genome sequencing project, we performed a cluster-based repeat analysis utilizing RepeatExplorer2 software. This analysis identified the most prevalent repetitive DNA element of the A. lumbricoides germline genome (AGR, Ascaris germline repeat), which was then used to develop an improved qPCR assay. During experimental validation, this assay demonstrated a fold increase in sensitivity of ~3,100, as determined by relative Cq values, when compared with an assay utilizing a previously published, frequently employed, ribosomal internal transcribed spacer (ITS) DNA target. A comparative analysis of 2,784 field-collected samples was then performed, successfully verifying this improved sensitivity. Conclusions/Significance Through analysis of the germline genome sequence of A. lumbricoides, a vastly improved qPCR assay has been developed. This assay, utilizing a high copy-number repeat target found in eggs and embryos (the AGR repeat), will improve prevalence estimates that are fundamental to the programmatic decision-making process, while simultaneously strengthening mathematical models used to examine STH infection rates. Furthermore, through the identification of an optimal target for PCR, future assay development efforts will also benefit, as the identity of the optimized repeat DNA target is likely to remain unchanged despite continued improvement in PCR-based diagnostic technologies. With an at-risk population in the billions, Ascaris lumbricoides is a pathogen of great global importance. In recent years, efforts to control the spread of this parasitic helminth have expanded, resulting in declining infection rates and worm burdens in some regions. While immeasurably important for global health, these declines have also served to expose the shortcomings of traditional diagnostic methods, as low-levels of pathogen generate a need for more sensitive tools, and microscopy-based techniques are proving ill-suited to the task at hand. Thankfully, improved sensitivity can be achieved through the careful selection of optimal repetitive DNA targets for PCR. However, previous attempts to identify such targets in A. lumbricoides were unsuccessful, largely due to chromosome diminution, an unusual phenomenon occurring in the Ascaridida, whereby large portions of the germline genome are reproducibly eliminated during early development, resulting in their absence in larvae or adult worms. As the stool-based molecular diagnosis of A. lumbricoides infection is primarily dependent upon the identification of egg-derived DNA, utilizing genomic DNA from adult worms for molecular target selection eliminates germline candidates and results in suboptimal target sequence choices. Recently, the publication of a pre-diminution germline genome of A. lumbricoides has provided us with an opportunity to re-evaluate target selection, facilitating the development of a novel quantitative real-time PCR assay with greatly improved sensitivity (~3100-fold as determined by relative Cq value) over previously developed assays that were based on ribosomal repeat DNA sequences with lower copy numbers.
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Effects of single and integrated water, sanitation, handwashing, and nutrition interventions on child soil-transmitted helminth and Giardia infections: A cluster-randomized controlled trial in rural Kenya. PLoS Med 2019; 16:e1002841. [PMID: 31242190 PMCID: PMC6594579 DOI: 10.1371/journal.pmed.1002841] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 05/28/2019] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Helminth and protozoan infections affect more than 1 billion children globally. Improving water quality, sanitation, handwashing, and nutrition could be more sustainable control strategies for parasite infections than mass drug administration, while providing other quality of life benefits. METHODS AND FINDINGS We enrolled geographic clusters of pregnant women in rural western Kenya into a cluster-randomized controlled trial (ClinicalTrials.gov NCT01704105) that tested 6 interventions: water treatment, improved sanitation, handwashing with soap, combined water treatment, sanitation, and handwashing (WSH), improved nutrition, and combined WSH and nutrition (WSHN). We assessed intervention effects on parasite infections by measuring Ascaris lumbricoides, Trichuris trichiura, hookworm, and Giardia duodenalis among children born to the enrolled pregnant women (index children) and their older siblings. After 2 years of intervention exposure, we collected stool specimens from 9,077 total children aged 2 to 15 years in 622 clusters, including 2,346 children in an active control group (received household visits but no interventions), 1,117 in the water treatment arm, 1,160 in the sanitation arm, 1,141 in the handwashing arm, 1,064 in the WSH arm, 1,072 in the nutrition arm, and 1,177 in the WSHN arm. In the control group, 23% of children were infected with A. lumbricoides, 1% with T. trichiura, 2% with hookworm, and 39% with G. duodenalis. The analysis included 4,928 index children (median age in years: 2) and 4,149 older siblings (median age in years: 5); study households had an average of 5 people, <10% had electricity access, and >90% had dirt floors. Compared to the control group, Ascaris infection prevalence was lower in the water treatment arm (prevalence ratio [PR]: 0.82 [95% CI 0.67, 1.00], p = 0.056), the WSH arm (PR: 0.78 [95% CI 0.63, 0.96], p = 0.021), and the WSHN arm (PR: 0.78 [95% CI 0.64, 0.96], p = 0.017). We did not observe differences in Ascaris infection prevalence between the control group and the arms with the individual interventions sanitation (PR: 0.89 [95% CI 0.73, 1.08], p = 0.228), handwashing (PR: 0.89 [95% CI 0.73, 1.09], p = 0.277), or nutrition (PR: 86 [95% CI 0.71, 1.05], p = 0.148). Integrating nutrition with WSH did not provide additional benefit. Trichuris and hookworm were rarely detected, resulting in imprecise effect estimates. No intervention reduced Giardia. Reanalysis of stool samples by quantitative polymerase chain reaction confirmed the reductions in Ascaris infections measured by microscopy in the WSH and WSHN groups. Trial limitations included imperfect uptake of targeted intervention behaviors, limited power to detect effects on rare parasite infections, and that it was not feasible to blind participants and sample collectors to treatment status. However, lab technicians and data analysts were blinded to treatment status. The trial was funded by the Bill & Melinda Gates Foundation and the United States Agency for International Development. CONCLUSIONS Integration of improved water quality, sanitation, and handwashing could contribute to sustainable control strategies for Ascaris infections, particularly in similar settings with recent or ongoing deworming programs. Combining nutrition with WSH did not provide further benefits, and water treatment alone was similarly effective to integrated WSH. Our findings provide new evidence that drinking water should be given increased attention as a transmission pathway for Ascaris. TRIAL REGISTRATION ClinicalTrials.gov NCT01704105.
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Steinbaum L, Mboya J, Mahoney R, Njenga SM, Null C, Pickering AJ. Effect of a sanitation intervention on soil-transmitted helminth prevalence and concentration in household soil: A cluster-randomized controlled trial and risk factor analysis. PLoS Negl Trop Dis 2019; 13:e0007180. [PMID: 30742614 PMCID: PMC6386409 DOI: 10.1371/journal.pntd.0007180] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 02/22/2019] [Accepted: 01/22/2019] [Indexed: 12/19/2022] Open
Abstract
Improved sanitation has been associated with a reduced prevalence of soil-transmitted helminth (STH) infection and has been hypothesized to prevent fecal contamination from spreading throughout the household environment. We evaluated the effect of providing households with a pit latrine with a plastic slab and drophole cover, child feces management tools, and associated behavioral messaging on reducing STH eggs in household soil. We collected soil samples from 2107 households (898 control and 1209 improved sanitation intervention households) that were enrolled in the WASH Benefits cluster randomized controlled trial in rural Kenya and performed a post-intervention analysis after two years of intervention exposure. Following a pre-specified analysis plan, we combined all households that received the sanitation intervention into one group for comparison to control households. The prevalence of STH eggs in soil was 18.9% in control households and 17.0% in intervention households. The unadjusted prevalence ratio of total STH eggs in the intervention groups compared to the control group was 0.94 (95% CI: 0.78-1.13). The geometric mean concentration was 0.05 eggs/g dry soil in control households and intervention households. Unadjusted and adjusted models gave similar results. We found use of a shared latrine, presence of a roof over the sampling area, and the number of dogs owned at baseline was associated with an increased prevalence of STH eggs in soil; the presence of a latrine that was at least 2 years old and a latrine with a covered drophole was associated with a reduction in the prevalence of STH eggs in soil. Soil moisture content was also associated with an increased prevalence of STH eggs in soil. Our results indicate that an intervention designed to increase access to improved latrines and child feces management tools may not be enough to impact environmental occurrence of STH in endemic areas where latrine coverage is already high.
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Affiliation(s)
- Lauren Steinbaum
- Civil and Environmental Engineering, Stanford University, Stanford, California, United States of America
- Epidemiology and Biostatistics, University of Georgia, Athens, Georgia, United States of America
| | - John Mboya
- Innovations for Poverty Action, Nairobi, Kenya
| | - Ryan Mahoney
- Innovations for Poverty Action, New Haven, Connecticut, United States of America
| | - Sammy M. Njenga
- Eastern and Southern Africa Center of International Parasite Control, Kenya Medical Research Institute (KEMRI), Nairobi, Kenya
| | - Clair Null
- Innovations for Poverty Action, New Haven, Connecticut, United States of America
- Mathematica, Washington, D.C., United States of America
| | - Amy J. Pickering
- Civil and Environmental Engineering, Stanford University, Stanford, California, United States of America
- Civil and Environmental Engineering, Tufts University, Medford, Massachusetts, United States of America
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Abraham D, Kaliappan SP, Walson JL, Rao Ajjampur SS. Intervention strategies to reduce the burden of soil-transmitted helminths in India. Indian J Med Res 2018; 147:533-544. [PMID: 30168484 PMCID: PMC6118140 DOI: 10.4103/ijmr.ijmr_881_18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Soil-transmitted helminth (STH) infections continue to be a major global cause of morbidity, with a large proportion of the burden of STH infections occurring in India. In addition to direct health impacts of these infections, including anaemia and nutritional deficiencies in children, these infections also significantly impact economic development, as a result of delays in early childhood cognitive development and future income earning potential. The current World Health Organization strategy for STH is focused on morbidity control through the application of mass drug administration to all pre-school-aged and school-aged children. In India, the control of STH-related morbidity requires mobilization of significant human and financial resources, placing additional burdens on limited public resources. Infected adults and untreated children in the community act as a reservoir of infection by which treated children get rapidly reinfected. As a result, deworming programmes will need to be sustained indefinitely in the absence of other strategies to reduce reinfection, including water, hygiene and sanitation interventions (WASH). However, WASH interventions require sustained effort by the government or other agencies to build infrastructure and to promote healthy behavioural modifications, and their effectiveness is often limited by deeply entrenched cultural norms and behaviours. Novel strategies must be explored to provide a lasting solution to the problem of STH infections in India other than the indefinite provision of deworming for morbidity control.
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Affiliation(s)
- Dilip Abraham
- Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
| | | | - Judd L Walson
- Department of Global Health, Medicine (Infectious Disease), Paediatrics & Epidemiology, University of Washington, Seattle, USA; DeWorm3, Division of Life Sciences, Natural History Museum, London, UK
| | - Sitara Swarna Rao Ajjampur
- Wellcome Trust Research Laboratory, Division of Gastrointestinal Sciences, Christian Medical College, Vellore, India
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25
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Mpairwe H, Amoah AS. Parasites and allergy: Observations from Africa. Parasite Immunol 2018; 41:e12589. [PMID: 30216486 PMCID: PMC6587767 DOI: 10.1111/pim.12589] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 08/15/2018] [Accepted: 09/10/2018] [Indexed: 12/17/2022]
Abstract
Population studies from the African continent have observed a marked increase in the prevalence of allergy‐related diseases over the past few decades, but the cause of this rise is not fully understood. The most investigated potential risk factor has been the relationship between exposure to helminths and allergy‐related outcomes. Immunologically, parallels exist between responses to helminths and to allergens as both are associated with elevated levels of immunoglobulin E, increased numbers of T helper 2 cells and other immune cells. However, epidemiological studies from the African continent have found inconsistent results. In this review, observations from population studies carried out in Africa over the last decade that focus on the relationship between helminth infections and allergy‐related outcomes are examined. How these findings advance our understanding of the complex interactions between helminths and allergies at the population level is also explored as well as some of the underlying immune mechanisms involved. This knowledge is important for better diagnosis, treatment and prevention of allergy‐related diseases and has wider global significance.
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Affiliation(s)
- Harriet Mpairwe
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Abena S Amoah
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
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Abstract
Climate change is expected to impact across every domain of society, including health. The majority of the world's population is susceptible to pathological, infectious disease whose life cycles are sensitive to environmental factors across different physical phases including air, water and soil. Nearly all so-called neglected tropical diseases (NTDs) fall into this category, meaning that future geographic patterns of transmission of dozens of infections are likely to be affected by climate change over the short (seasonal), medium (annual) and long (decadal) term. This review offers an introduction into the terms and processes deployed in modelling climate change and reviews the state of the art in terms of research into how climate change may affect future transmission of NTDs. The 34 infections included in this chapter are drawn from the WHO NTD list and the WHO blueprint list of priority diseases. For the majority of infections, some evidence is available of which environmental factors contribute to the population biology of parasites, vectors and zoonotic hosts. There is a general paucity of published research on the potential effects of decadal climate change, with some exceptions, mainly in vector-borne diseases.
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Affiliation(s)
- Mark Booth
- Newcastle University, Institute of Health and Society, Newcastle upon Tyne, United Kingdom.
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Steinbaum L, Swarthout J, Mboya J, Pickering AJ. Following the Worms: Detection of Soil-Transmitted Helminth Eggs on Mothers' Hands and Household Produce in Rural Kenya. Am J Trop Med Hyg 2017; 97:1616-1618. [PMID: 28820692 PMCID: PMC5817747 DOI: 10.4269/ajtmh.17-0072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Approximately one-quarter of the world’s population is infected with at least one species of soil-transmitted helminth (STH). The role of produce and hands in STH transmission is not well understood. We collected and processed mother hand rinse and garden-grown produce rinse samples from 116 rural households in Kakamega, Kenya, in an area previously identified to have high STH egg contamination in household soil. Ascaris was the only STH species detected; 0.9% of hand rinse, 3.5% of leafy produce, and 1.8% of root produce samples had Ascaris eggs. Our results indicate produce and hands can carry Ascaris eggs. However, due to the low detected prevalence of eggs on hands and produce, and a high prevalence of cooking the produce items tested, these pathways might have a minor contribution to STH exposure in this setting.
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Affiliation(s)
- Lauren Steinbaum
- Civil and Environmental Engineering, Stanford University, Stanford, California
| | | | - John Mboya
- Innovations for Poverty Action, Nairobi, Kenya
| | - Amy J Pickering
- Civil and Environmental Engineering, Tufts University, Medford, Massachusetts.,Civil and Environmental Engineering, Stanford University, Stanford, California
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Steinbaum L, Kwong LH, Ercumen A, Negash MS, Lovely AJ, Njenga SM, Boehm AB, Pickering AJ, Nelson KL. Detecting and enumerating soil-transmitted helminth eggs in soil: New method development and results from field testing in Kenya and Bangladesh. PLoS Negl Trop Dis 2017; 11:e0005522. [PMID: 28379956 PMCID: PMC5393894 DOI: 10.1371/journal.pntd.0005522] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 04/17/2017] [Accepted: 03/23/2017] [Indexed: 12/17/2022] Open
Abstract
Globally, about 1.5 billion people are infected with at least one species of soil-transmitted helminth (STH). Soil is a critical environmental reservoir of STH, yet there is no standard method for detecting STH eggs in soil. We developed a field method for enumerating STH eggs in soil and tested the method in Bangladesh and Kenya. The US Environmental Protection Agency (EPA) method for enumerating Ascaris eggs in biosolids was modified through a series of recovery efficiency experiments; we seeded soil samples with a known number of Ascaris suum eggs and assessed the effect of protocol modifications on egg recovery. We found the use of 1% 7X as a surfactant compared to 0.1% Tween 80 significantly improved recovery efficiency (two-sided t-test, t = 5.03, p = 0.007) while other protocol modifications—including different agitation and flotation methods—did not have a significant impact. Soil texture affected the egg recovery efficiency; sandy samples resulted in higher recovery compared to loamy samples processed using the same method (two-sided t-test, t = 2.56, p = 0.083). We documented a recovery efficiency of 73% for the final improved method using loamy soil in the lab. To field test the improved method, we processed soil samples from 100 households in Bangladesh and 100 households in Kenya from June to November 2015. The prevalence of any STH (Ascaris, Trichuris or hookworm) egg in soil was 78% in Bangladesh and 37% in Kenya. The median concentration of STH eggs in soil in positive samples was 0.59 eggs/g dry soil in Bangladesh and 0.15 eggs/g dry soil in Kenya. The prevalence of STH eggs in soil was significantly higher in Bangladesh than Kenya (chi-square, χ2 = 34.39, p < 0.001) as was the concentration (Mann-Whitney, z = 7.10, p < 0.001). This new method allows for detecting STH eggs in soil in low-resource settings and could be used for standardizing soil STH detection globally. Intestinal worm infections are common in populations living in tropical, low-income countries. People primarily become infected when they consume intestinal worm eggs from contaminated water, hands, and food. Intestinal worm eggs are transmitted from infected people and spread through the environment, particularly via soil. There is no standard laboratory method for counting intestinal worm eggs in soil, which is a major barrier to comprehensive research on the transmission of infection. We tested different laboratory protocol steps to extract soil-transmitted helminth eggs, which is one type of intestinal worm, from soil and propose a new, fast, and efficient field method. We tested the method in Kenya and Bangladesh and found that soil contamination with helminth eggs was prevalent in both study areas. We propose that environmental contamination be included in discussions about intestinal worm transmission, control, and elimination, especially in areas with low infection prevalence. The method we propose will help researchers assess soil contamination, which can be used to examine the effectiveness of intestinal worm transmission control measures.
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Affiliation(s)
- Lauren Steinbaum
- Civil and Environmental Engineering, Stanford University, Stanford, California, United States of America
| | - Laura H. Kwong
- Civil and Environmental Engineering, Stanford University, Stanford, California, United States of America
| | - Ayse Ercumen
- School of Public Health, University of California, Berkeley, Berkeley, California, United States of America
| | - Makeda S. Negash
- Integrative Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - Amira J. Lovely
- School of Public Health, University of California, Berkeley, Berkeley, California, United States of America
| | - Sammy M. Njenga
- Eastern and Southern Africa Center of International Parasite Control, Kenya Medical Research Institute (KEMRI), Nairobi, Kenya
| | - Alexandria B. Boehm
- Civil and Environmental Engineering, Stanford University, Stanford, California, United States of America
| | - Amy J. Pickering
- Civil and Environmental Engineering, Stanford University, Stanford, California, United States of America
| | - Kara L. Nelson
- Civil and Environmental Engineering, University of California, Berkeley, Berkeley, California, United States of America
- * E-mail:
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