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Medley GF, Turner HC, Baggaley RF, Holland C, Hollingsworth TD. The Role of More Sensitive Helminth Diagnostics in Mass Drug Administration Campaigns: Elimination and Health Impacts. Adv Parasitol 2016; 94:343-392. [PMID: 27756457 DOI: 10.1016/bs.apar.2016.08.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Diagnostics play a crucial role in determining treatment protocols and evaluating success of mass drug administration (MDA) programmes used to control soil-transmitted helminths (STHs). The current diagnostic, Kato-Katz, relies on inexpensive, reusable materials and can be used in the field, but only trained microscopists can read slides. This diagnostic always underestimates the true prevalence of infection, and the accuracy worsens as the true prevalence falls. We investigate how more sensitive diagnostics would impact on the management and life cycle of MDA programmes, including number of mass treatment rounds, health impact, number of unnecessary treatments and probability of elimination. We use an individual-based model of STH transmission within the current World Health Organization (WHO) treatment guidelines which records individual disability-adjusted life years (DALY) lost. We focus on Ascaris lumbricoides due to the availability of high-quality data on existing diagnostics. We show that the effect of improving the sensitivity of diagnostics is principally determined by the precontrol prevalence in the community. Communities at low true prevalence (<30%) and high true prevalence (>70%) do not benefit greatly from improved diagnostics. Communities with intermediate prevalence benefit greatly from increased chemotherapy application, both in terms of reduced DALY loss and increased probability of elimination. Our results suggest that programmes should be extended beyond school-age children, especially in high prevalence communities. Finally, we argue against using apparent or measured prevalence as an uncorrected proxy for true prevalence.
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Affiliation(s)
- G F Medley
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - H C Turner
- Imperial College London, London, United Kingdom
| | - R F Baggaley
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - C Holland
- Trinity College Dublin, Dublin, Ireland
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Deori K, Yadav AK. Anthelmintic effects of Oroxylum indicum stem bark extract on juvenile and adult stages of Hymenolepis diminuta (Cestoda), an in vitro and in vivo study. Parasitol Res 2015; 115:1275-85. [PMID: 26660694 DOI: 10.1007/s00436-015-4864-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Accepted: 11/30/2015] [Indexed: 12/25/2022]
Abstract
Worldwide, traditional usage of herbal medicines is a common practice to treat various parasitic infections. In India, bark decoction of Oroxylum indicum (L.) Kurz. (Bignoniaceae) is used as a traditional medicine to cure intestinal-helminthic infections. This study investigated the anthelmintic efficacy of methanolic bark extract of O. indicum on Hymenolepis diminuta (Cestoda), using both in vitro and in vivo methods. Utilizing a mini-questionnaire, first, we collected information about the pattern of anthelmintic use of this plant. Later, in vitro efficacy of extract was tested at 10, 20 and 30 mg/ml on both the artificially excysted juveniles and adult H. diminuta worms. Herein, scanning electron microscopy (SEM) was also utilized to determine the possible effects of extract on tegumental surfaces of juvenile and adult cestode. In vivo, extract was tested at 250, 500 and 1000 mg/kg in H. diminuta albino rat model, against juvenile and adult cestode. Praziquantel (PZQ) served as reference drug in anthelmintic assays. The acute toxicity of extract was determined as per the OECD guidelines. The field questionnaire data revealed that 78 % of people in the area use O. indicum stem bark against intestinal helminths, and of these, 75 % of people also believed it highly efficacious anthelmintic remedy. In vitro testing of extract revealed significant effects on juvenile worms, and 30 mg/ml of extract caused mortality of juveniles at the initial period (0.25 ± 0.00 h). Conversely, PZQ (1 mg/ml) showed paralysis and mortality of juvenile cestodes in 0.44 ± 0.04 and 1.11 ± 0.06 h, respectively. As determined by SEM, in vitro exposure to extract showed substantial effects on both juveniles and adult worms in the form of wrinkled scolex, distorted tegument and eroded microtriches. In vivo study revealed better efficacy of extract against juveniles than adult stages of parasite. Treatment of rats with 1000 mg/kg of extract caused 79.3 % reduction in EPG counts and 70.8 % of reduction in worm counts, which compared well to PZQ efficacy. In acute toxicity study, administration of a single oral dose of 2000 mg/kg of extract to mice did not cause any signs of toxicity or mortality within 2-week observation. Hence, the LD50 of extract was estimated to be greater than 2000 mg/kg. In conclusion, the bark extract of O. indicum possesses concentration-dependent effects against the larval and adult H. diminuta worms, and thus the extract holds promise in the control of intestinal helminthiases. This also supports the common belief of people about the reputation of this plant as anthelmintic in traditional medicine. There is a need to standardize the formulations of this plant for their possible use as standardized herbal anthelmintic agents in the future.
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Affiliation(s)
- Khirod Deori
- Department of Zoology, North-Eastern Hill University, Shillong, 793 022, India
| | - Arun K Yadav
- Department of Zoology, North-Eastern Hill University, Shillong, 793 022, India.
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153
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Ferreira FS, Baptista-Fernandes T, Oliveira D, Rodrigues R, Neves E, Lima A, Garrido E, Afonso G, Zaky A, Telles de Freitas P, Atouguia J, Centeno-Lima S. Giardia duodenalis and soil-transmitted helminths infections in children in São Tomé and Príncipe: do we think Giardia when addressing parasite control? J Trop Pediatr 2015; 61:106-12. [PMID: 25604490 DOI: 10.1093/tropej/fmu078] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Giardia duodenalis prevalence is commonly as high as soil-transmitted helminths (STH), nevertheless is not considered for large-scale chemotherapy through mass drug administration (MDA) due to its short incubation period and frequent reinfections, its control being associated to improving access to water and sanitation. A study enrolling 444 children attending preschools was conducted in May 2011 during a deworming campaign. Faecal samples were obtained and analysed through microscopy of wet mounting and after Kato-Katz and formol-ether concentration techniques. The majority of children were infected with at least one pathogenic parasite (86.7%, 385 of 444). Ascaris lumbricoides and Trichuris trichiura (56.3%, 250 of 444 and 52.5%, 233 of 444, respectively) were the most frequent parasites followed by G. duodenalis infecting 41.7% (185 of 444) of the children. The present work aimed at obtaining updated information concerning intestinal parasite infections in children attending preschools in São Tomé and Príncipe and to contribute for the adequate management of the enteric infections.
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Affiliation(s)
- Filipa Santana Ferreira
- Unidade de Clínica Tropical e Centro de Malária e Doenças Tropicais-LA, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, 1349-008 Lisboa, Portugal
| | - Teresa Baptista-Fernandes
- Laboratório de Microbiologia Clínica e Biologia Molecular, Hospital Egas Moniz, Serviço de Patologia Clínica do Centro Hospitalar Lisboa Ocidental, 1349-019 Lisboa, Portugal
| | | | - Rúben Rodrigues
- Unidade de Clínica Tropical e Centro de Malária e Doenças Tropicais-LA, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, 1349-008 Lisboa, Portugal
| | - Edgar Neves
- Instituto Marquês de Valle Flôr, São Tomé Office, 280, São Tomé
| | - António Lima
- Instituto Marquês de Valle Flôr, São Tomé Office, 280, São Tomé
| | - Eduardo Garrido
- Instituto Marquês de Valle Flôr, São Tomé Office, 280, São Tomé
| | | | - Ahmed Zaky
- Instituto Marquês de Valle Flôr, 1100-548 Lisboa, Portugal
| | - Paulo Telles de Freitas
- Instituto Marquês de Valle Flôr, 1100-548 Lisboa, Portugal Serviço de Medicina Intensiva, Hospital Prof. Doutor Fernando Fonseca, 2720-276 Amadora, Portugal
| | - Jorge Atouguia
- Unidade de Clínica Tropical e Centro de Malária e Doenças Tropicais-LA, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, 1349-008 Lisboa, Portugal
| | - Sónia Centeno-Lima
- Unidade de Clínica Tropical e Centro de Malária e Doenças Tropicais-LA, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, 1349-008 Lisboa, Portugal
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154
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Levecke B, Anderson RM, Berkvens D, Charlier J, Devleesschauwer B, Speybroeck N, Vercruysse J, Van Aelst S. Mathematical inference on helminth egg counts in stool and its applications in mass drug administration programmes to control soil-transmitted helminthiasis in public health. Adv Parasitol 2015; 87:193-247. [PMID: 25765196 DOI: 10.1016/bs.apar.2015.01.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the present study, we present a hierarchical model based on faecal egg counts (FECs; expressed in eggs per 1g of stool) in which we first describe the variation in FECs between individuals in a particular population, followed by describing the variance due to counting eggs under a microscope separately for each stool sample. From this general framework, we discuss how to calculate a sample size for assessing a population mean FEC and the impact of an intervention, measured as reduction in FECs, for any scenario of soil-transmitted helminth (STH) epidemiology (the intensity and aggregation of FECs within a population) and diagnostic strategy (amount of stool examined (∼sensitivity of the diagnostic technique) and examination of individual/pooled stool samples) and on how to estimate prevalence of STH in the absence of a gold standard. To give these applications the most wide relevance as possible, we illustrate each of them with hypothetical examples.
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Affiliation(s)
- Bruno Levecke
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Roy M Anderson
- Imperial College London, Department of Infectious Disease Epidemiology, Faculty of Medicine, School of Public Health St Mary's Campus, Norfolk Place, London, UK
| | - Dirk Berkvens
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Johannes Charlier
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Brecht Devleesschauwer
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium; Institute of Health and Society (IRSS), Université catholique de Louvain, Brussels, Belgium
| | - Niko Speybroeck
- Institute of Health and Society (IRSS), Université catholique de Louvain, Brussels, Belgium
| | - Jozef Vercruysse
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Stefan Van Aelst
- Department of Applied Mathematics, Computer Science and Statistics, Faculty of Sciences, Ghent University, Ghent, Belgium; Department of Mathematics, Faculty of Sciences, KU Leuven University, Leuven, Belgium
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155
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Karagiannis-Voules DA, Odermatt P, Biedermann P, Khieu V, Schär F, Muth S, Utzinger J, Vounatsou P. Geostatistical modelling of soil-transmitted helminth infection in Cambodia: do socioeconomic factors improve predictions? Acta Trop 2015; 141:204-12. [PMID: 25205492 DOI: 10.1016/j.actatropica.2014.09.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 08/19/2014] [Accepted: 09/01/2014] [Indexed: 11/23/2022]
Abstract
Soil-transmitted helminth infections are intimately connected with poverty. Yet, there is a paucity of using socioeconomic proxies in spatially explicit risk profiling. We compiled household-level socioeconomic data pertaining to sanitation, drinking-water, education and nutrition from readily available Demographic and Health Surveys, Multiple Indicator Cluster Surveys and World Health Surveys for Cambodia and aggregated the data at village level. We conducted a systematic review to identify parasitological surveys and made every effort possible to extract, georeference and upload the data in the open source Global Neglected Tropical Diseases database. Bayesian geostatistical models were employed to spatially align the village-aggregated socioeconomic predictors with the soil-transmitted helminth infection data. The risk of soil-transmitted helminth infection was predicted at a grid of 1×1km covering Cambodia. Additionally, two separate individual-level spatial analyses were carried out, for Takeo and Preah Vihear provinces, to assess and quantify the association between soil-transmitted helminth infection and socioeconomic indicators at an individual level. Overall, we obtained socioeconomic proxies from 1624 locations across the country. Surveys focussing on soil-transmitted helminth infections were extracted from 16 sources reporting data from 238 unique locations. We found that the risk of soil-transmitted helminth infection from 2000 onwards was considerably lower than in surveys conducted earlier. Population-adjusted prevalences for school-aged children from 2000 onwards were 28.7% for hookworm, 1.5% for Ascaris lumbricoides and 0.9% for Trichuris trichiura. Surprisingly, at the country-wide analyses, we did not find any significant association between soil-transmitted helminth infection and village-aggregated socioeconomic proxies. Based also on the individual-level analyses we conclude that socioeconomic proxies might not be good predictors at an aggregated large-scale analysis due to their large between- and within-village heterogeneity. Specific information of both the infection risk and potential predictors might be needed to obtain any existing association. The presented soil-transmitted helminth infection risk estimates for Cambodia can be used for guiding and evaluating control and elimination efforts.
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156
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Montresor A, À Porta N, Albonico M, Gabrielli AF, Jankovic D, Fitzpatrick C, Vercruysse J, Levecke B. Soil-transmitted helminthiasis: the relationship between prevalence and classes of intensity of infection. Trans R Soc Trop Med Hyg 2014; 109:262-7. [PMID: 25404186 DOI: 10.1093/trstmh/tru180] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Recently, WHO has developed a predictive model to evaluate the impact of preventive chemotherapy programs to control the morbidity of soil-transmitted helminths (STHs). To make predictions, this model needs baseline information about the proportion of infections classified as low, moderate and high intensity, for each of the three STH species. However, epidemiological data available are often limited to prevalence estimates. METHODS We reanalyzed available data from 19 surveys in 10 countries and parameterized the relationship between prevalence of STH infections and the proportion of moderate and heavy intensity infections. RESULTS The equations derived allow feeding the WHO model with estimates of the proportion of the different classes of infection intensity when only prevalence data is available. CONCLUSIONS The prediction capacities of the STH model using the equations developed in the present study, should be tested by comparing it with the changes on STH epidemiological data observed in control programs operating for several years.
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Affiliation(s)
- Antonio Montresor
- Department of Control of Neglected Tropical Diseases, World Health Organization, 20 Av Appia, Geneva 1211, Switzerland
| | - Natacha À Porta
- Department of Control of Neglected Tropical Diseases, World Health Organization, 20 Av Appia, Geneva 1211, Switzerland
| | | | - Albis Francesco Gabrielli
- Department of Control of Neglected Tropical Diseases, World Health Organization, 20 Av Appia, Geneva 1211, Switzerland
| | - Dina Jankovic
- Centre for Health Economics, University of York, York, UK
| | - Christopher Fitzpatrick
- Department of Control of Neglected Tropical Diseases, World Health Organization, 20 Av Appia, Geneva 1211, Switzerland
| | - Jozef Vercruysse
- Department of Virology, Parasitology and Immunology, Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium
| | - Bruno Levecke
- Department of Virology, Parasitology and Immunology, Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium
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157
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Dana D, Mekonnen Z, Emana D, Ayana M, Getachew M, Workneh N, Vercruysse J, Levecke B. Prevalence and intensity of soil-transmitted helminth infections among pre-school age children in 12 kindergartens in Jimma Town, southwest Ethiopia. Trans R Soc Trop Med Hyg 2014; 109:225-7. [PMID: 25371496 DOI: 10.1093/trstmh/tru178] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Pre-school age children (preSAC) remain difficult to reach in mass drug administration (MDA) programmes to control soil-transmitted helminth (STH) infections. Kindergartens provide a unique platform to increase the coverage of MDA in preSAC in Ethiopia, but surveys assessing STHs among preSAC in kindergartens are scarce. METHODS We report the prevalence and intensity of STH infections among 622 preSAC in 12 kindergartens in Jimma, Ethiopia. RESULTS STHs were found in all kindergartens, with prevalence exceeding 50% in 8 kindergartens. The majority of the infections were of low intensity. CONCLUSIONS This study highlights the importance of kindergartens as an additional opportunity for MDA in Ethiopia.
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Affiliation(s)
- Daniel Dana
- Department of Medical Laboratory Sciences and Pathology, College of Public Health and Medical Sciences, Jimma University, Jimma, Ethiopia
| | - Zeleke Mekonnen
- Department of Medical Laboratory Sciences and Pathology, College of Public Health and Medical Sciences, Jimma University, Jimma, Ethiopia
| | - Daniel Emana
- Department of Medical Laboratory Sciences and Pathology, College of Public Health and Medical Sciences, Jimma University, Jimma, Ethiopia
| | - Mio Ayana
- Department of Medical Laboratory Sciences and Pathology, College of Public Health and Medical Sciences, Jimma University, Jimma, Ethiopia
| | - Mestawet Getachew
- Department of Pharmacy, College of Public Health and Medical Sciences, Jimma University, Jimma, Ethiopia
| | - Netsanet Workneh
- Department of Paediatrics, College of Public Health and Medical Sciences, Jimma University, Jimma, Ethiopia
| | - Jozef Vercruysse
- Department of Virology, Parasitology and Immunology, Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium
| | - Bruno Levecke
- Department of Virology, Parasitology and Immunology, Ghent University, Faculty of Veterinary Medicine, Merelbeke, Belgium
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158
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Bardosh K, Inthavong P, Xayaheuang S, Okello AL. Controlling parasites, understanding practices: the biosocial complexity of a One Health intervention for neglected zoonotic helminths in northern Lao PDR. Soc Sci Med 2014; 120:215-23. [PMID: 25261615 DOI: 10.1016/j.socscimed.2014.09.030] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 09/15/2014] [Accepted: 09/16/2014] [Indexed: 11/25/2022]
Abstract
A parasitological survey in northern Lao PDR showed a remote ethnic minority village to be hyper-endemic for Taenia solium, a Neglected Tropical Disease (NTD) that impacts human and pig health. An intervention combining human Mass Drug Administration (MDA) with porcine vaccination and antihelmintic treatment was then implemented, targeting both T. solium and other soil-transmitted helminths. To understand the biosocial complexity of this integrated One Health intervention, we conducted a rapid ethnographic study exploring the transmission dynamics of T. solium and locally acceptable long-term control options. Informed by two years of project work in the village, this included six focus group discussions, 35 semi-structured interviews, a latrine survey, a school-based education meeting, participant observation and many unstructured interviews conducted over two weeks in October 2013. We found that risk behaviours were mediated by various social determinants including limited market access, interrelationships between alcohol, ancestral sacrifices and the consumption of raw pork, seasonal variations and poor latrine coverage. Only sixteen percent of households had latrines, attributed to the unacceptability of dry latrines, lack of water access, poor building techniques and poverty. Whilst women could explain T. solium transmission, most men and children could not, revealing that distributed posters/leaflets relied too heavily on text and ambiguous images. Compliance with MDA was high due to trust between project staff and village leaders. However understandings of pharmacology, minor side effects, human migration and children's fear of worms may lead to resistance in future programmes. Our research highlights the complexities of controlling T. solium and other soil-transmitted helminths in a remote ethnic minority village and the need to integrate biomedical and participatory approaches. Although we showcase the heuristic value of using rapid ethnography to inform intervention strategies as part of a One Health/NTD agenda, we also identify several possible paradoxes and conundrums in embedding locally-grounded biosocial analysis into NTD programmes. These need to be acknowledged and negotiated by multidisciplinary teams.
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Affiliation(s)
- Kevin Bardosh
- School of Social and Political Science, The University of Edinburgh, 58 George Square, Edinburgh, United Kingdom; Division of Pathway Medicine and Centre for Infectious Diseases, School of Biomedical Sciences, College of Medicine and Veterinary Medicine, The University of Edinburgh, Edinburgh, United Kingdom.
| | - Phouth Inthavong
- National Animal Health Laboratory, Ministry of Agriculture and Forestry, Department of Livestock and Fisheries, Luang Prabang Road, Ban Huanmouang, Vientiane Capital, Lao Democratic People's Republic
| | - Sivilai Xayaheuang
- CSIRO Animal, Food and Health Sciences, Australian Animal Health Laboratory (AAHL) Regional Programme, 5 Portarlington Road, East Geelong, Victoria, Australia
| | - Anna L Okello
- National Animal Health Laboratory, Ministry of Agriculture and Forestry, Department of Livestock and Fisheries, Luang Prabang Road, Ban Huanmouang, Vientiane Capital, Lao Democratic People's Republic; CSIRO Animal, Food and Health Sciences, Australian Animal Health Laboratory (AAHL) Regional Programme, 5 Portarlington Road, East Geelong, Victoria, Australia
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159
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Kaminsky RG, Ault SK, Castillo P, Serrano K, Troya G. High prevalence of soil-transmitted helminths in Southern Belize-highlighting opportunity for control interventions. Asian Pac J Trop Biomed 2014; 4:345-53. [PMID: 25182717 DOI: 10.12980/apjtb.4.201414b3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 03/25/2014] [Indexed: 10/25/2022] Open
Abstract
OBJECTIVE To assess prevalence and intensity of soil-transmitted helminths (STH) in school age children of two southern districts as baseline information prior to implement a deworming program against intestinal parasites as part of an integrated country development plan. METHODS Children randomly selected from urban and rural schools in Southern Belize provided one stool sample each, analysed by the Kato-Katz method to assess prevalence and intensity of STH infections. Epi Info software was used for data analysis; Chi-square test and Fischer exact test were applied to compare group proportions; P<0.05 was considered of statistical significance; descriptive statistics were expressed as percentages. RESULTS A total of 500 children from 10 schools participated in the study from May to December 2005. Prevalence of STH ranged between 40% and 82% among schools, with a median of 59.2%; the majority of light intensity, and with 2.2% high intensity infection. Trichuris and Ascaris infections presented similar frequency in children aged from 6 to 9 years old; hookworm infections tended to be more frequent in the older group 10 to 12 years old. Statistical significances (P≤0.01) were found in children in rural schools infected with any species of STH, in moderate Trichuris infections, in hookworm infections in rural areas with strong Mayan presence and in Ascaris infections in children of Mayan origin. CONCLUSIONS High prevalence of STH in Southern Belize provided sound ground for implementing an integrated deworming control program.
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Affiliation(s)
- Rina Girard Kaminsky
- Department of Paediatrics, School of Medicine, National Autonomous University of Honduras and Parasitology Service, Department of Clinical Laboratory, University Hospital, Honduras
| | - Steven K Ault
- Department of Communicable Diseases and Health Analysis, Pan American Health Organization, Washington D.C., United States of America
| | - Phillip Castillo
- Southern Regional Hospital, Stann Creek District, Ministry of Health, Belize
| | - Kenton Serrano
- Southern Regional Hospital, Stann Creek District, Ministry of Health, Belize
| | - Guillermo Troya
- Head of PAHO/WHO in Suriname, former Services of Health Systems Consultant, PAHO/WHO, Belize
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160
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Panic G, Duthaler U, Speich B, Keiser J. Repurposing drugs for the treatment and control of helminth infections. Int J Parasitol Drugs Drug Resist 2014; 4:185-200. [PMID: 25516827 PMCID: PMC4266803 DOI: 10.1016/j.ijpddr.2014.07.002] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Revised: 07/04/2014] [Accepted: 07/13/2014] [Indexed: 01/01/2023]
Abstract
Drug repurposing continues to be the central drug discovery strategy for helminths. Most repurposed drugs come from veterinary medicine and known drug classes. Only a handful of drugs have advanced clinically. More collaborations and funding are needed to advance discoveries to the market.
Helminth infections are responsible for a considerable public health burden, yet the current drug armamentarium is small. Given the high cost of drug discovery and development, the high failure rates and the long duration to develop novel treatments, drug repurposing circumvents these obstacles by finding new uses for compounds other than those they were initially intended to treat. In the present review, we summarize in vivo and clinical trial findings testing clinical candidates and marketed drugs against schistosomes, food-borne trematodes, soil-transmitted helminths, Strongyloides stercoralis, the major human filariases lymphatic filariasis and onchocerciasis, taeniasis, neurocysticercosis and echinococcosis. While expanding the applications of broad-spectrum or veterinary anthelmintics continues to fuel alternative treatment options, antimalarials, antibiotics, antiprotozoals and anticancer agents appear to be producing fruitful results as well. The trematodes and nematodes continue to be most investigated, while cestodal drug discovery will need to be accelerated. The most clinically advanced drug candidates include the artemisinins and mefloquine against schistosomiasis, tribendimidine against liver flukes, oxantel pamoate against trichuriasis, and doxycycline against filariasis. Preclinical studies indicate a handful of promising future candidates, and are beginning to elucidate the broad-spectrum activity of some currently used anthelmintics. Challenges and opportunities are further discussed.
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Affiliation(s)
| | | | | | - Jennifer Keiser
- Corresponding author. Address: Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, P.O. Box, CH-4002 Basel, Switzerland. Tel.: +41 61 284 8218; fax: +41 61 284 8105.
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161
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Albonico M, Rinaldi L, Sciascia S, Morgoglione ME, Piemonte M, Maurelli MP, Musella V, Utzinger J, Ali SM, Ame SM, Cringoli G. Comparison of three copromicroscopic methods to assess albendazole efficacy against soil-transmitted helminth infections in school-aged children on Pemba Island. Trans R Soc Trop Med Hyg 2014; 107:493-501. [PMID: 23843559 DOI: 10.1093/trstmh/trt051] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The diagnostic accuracy of three faecal egg count techniques (Kato-Katz, McMaster and FLOTAC) to assess albendazole efficacy against soil-transmitted helminth (STH) infections was compared. METHODS The study is registered with Current Controlled Trials [identifier: ISRCTN90088840]. During September-November 2009, 304 school-aged children on Pemba Island, Tanzania, were screened and those infected with Ascaris lumbricoides, hookworm or Trichuris trichiura were treated with a single dose of albendazole (400 mg). Twenty-one days post-treatment, children provided a single stool sample which was examined using the same diagnostic methods. All stool samples were divided into two aliquots and one was fixed in 5% formalin and examined using FLOTAC and McMaster approximately 6 months after collection. RESULTS Using fresh stool samples, comparable prevalences were demonstrated for the three methods at baseline (90-92.2% for T. trichiura, 41.1-52.8% for hookworm, 32.9-37.2% for A. lumbricoides); FLOTAC was the most sensitive method at baseline and follow-up. Albendazole showed high cure rate (CR) against A. lumbricoides (90-97%), moderate CR against hookworm (63-72%) and very low CR against T. trichiura (6-9%), regardless of the technique used. Egg counts (eggs per gram) at baseline were similar for A. lumbricoides and for hookworm among the three methods, and higher using McMaster and Kato-Katz compared with FLOTAC for T. trichiura. All methods were similar for hookworm and A. lumbricoides egg reduction rate (ERR) estimation, but Kato-Katz indicated a significantly higher ERR than McMaster and FLOTAC for T. trichiura. Preserved stool samples revealed consistently lower FECs at baseline and follow-up for all STHs. CONCLUSION Further development and validation of standard protocols for anthelminthic drug efficacy evaluation must be pursued.
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Affiliation(s)
- Marco Albonico
- Department of Biology, University of Torino, 10122 Torino, Italy
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Staudacher O, Heimer J, Steiner F, Kayonga Y, Havugimana JM, Ignatius R, Musemakweri A, Ngabo F, Harms G, Gahutu JB, Mockenhaupt FP. Soil-transmitted helminths in southern highland Rwanda: associated factors and effectiveness of school-based preventive chemotherapy. Trop Med Int Health 2014; 19:812-24. [PMID: 24750543 DOI: 10.1111/tmi.12321] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVES Preventive chemotherapy of schoolchildren against soil-transmitted helminths (STHs) is widely implemented in Rwanda. However, data on its actual efficacy are lacking. We assessed prevalence, associated factors and manifestation of STH infection among schoolchildren in southern highland Rwanda as well as cure and reinfection rates. METHODS Six hundred and twenty-two children (rural, 301; urban, 321) were included preceding the administration of a single dose of 500 mg mebendazole. Before treatment, and after 2 and 15 weeks, STH infection was determined by Kato-Katz smears and by PCR assays for Ascaris lumbricoides. Clinical and anthropometric data, socio-economic status and factors potentially associated with STH infection were assessed. RESULTS Soil-transmitted helminth (STH) infection was present in 38% of rural and in 13% of urban schoolchildren. Ascaris lumbricoides accounted for 96% of infections. Of these, one-third was detected by PCR exclusively. Factors associated with STH infection differed greatly between rural and urban children. Likewise, STH infection was associated with stunting and anaemia only among urban children. The cure rate after 2 weeks was 92%. Among eight non-cleared A. lumbricoides infections, seven were submicroscopic. Reinfection within 3 months occurred in 7%, but the rate was higher among rural children, and with initially present infection, particularly at comparatively high intensity. CONCLUSIONS The rural-urban difference in factors associated with STH infection and in reinfection rates highlights the need for targeted interventions to reduce transmission. PCR assays may help in detecting low-level infections persisting after treatment. In southern Rwanda, mebendazole is highly effective against the STH infections predominated by A. lumbricoides.
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Affiliation(s)
- Olga Staudacher
- Institute of Tropical Medicine and International Health, Charité - Universitätsmedizin Berlin, Berlin, Germany
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Somvanshi VS, Ellis BL, Hu Y, Aroian RV. Nitazoxanide: nematicidal mode of action and drug combination studies. Mol Biochem Parasitol 2014; 193:1-8. [PMID: 24412397 DOI: 10.1016/j.molbiopara.2013.12.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 12/03/2013] [Accepted: 12/17/2013] [Indexed: 11/18/2022]
Abstract
Intestinal nematodes or roundworms (aka soil-transmitted helminths or STHs) cause great disease. They infect upwards of two billion people, leading to high morbidity and a range of health problems, especially in infected children and pregnant women. Development of resistance to the two main classes of drugs used to treat intestinal nematode infections of humans has been reported. To fight STH infections, we need new and more effective drugs and ways to improve the efficacy of the old drugs. One promising alternative drug is nitazoxanide (NTZ). NTZ, approved for treating human protozoan infections, was serendipitously shown to have therapeutic activity against STHs. However, its mechanism of action against nematodes is not known. Using the laboratory nematode Caenorhabditis elegans, we show that NTZ acts on the nematodes through avr-14, an alpha-type subunit of a glutamate-gated chloride ion channel known for its role in ivermectin susceptibility. In addition, a forward genetic screen to select C. elegans mutants resistant to NTZ resulted in isolation of two NTZ resistant mutants that are not in avr-14, suggesting that additional mechanisms are involved in resistance to NTZ. We found that NTZ combines synergistically with other classes of anthelmintic drugs, i.e. albendazole and pyrantel, making it a good candidate for further studies on its use in drug combination therapy of STH infections. Given NTZ acts against a wide range of nematode parasites, our findings also validate avr-14 as an excellent target for pan-STH therapy.
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Affiliation(s)
- Vishal S Somvanshi
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Brian L Ellis
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Yan Hu
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Raffi V Aroian
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California San Diego, La Jolla, CA, USA.
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164
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Ranjan S, Passi SJ, Singh SN. Prevalence and risk factors associated with the presence of Soil-Transmitted Helminths in children studying in Municipal Corporation of Delhi Schools of Delhi, India. J Parasit Dis 2013; 39:377-84. [PMID: 26345038 DOI: 10.1007/s12639-013-0378-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Accepted: 10/18/2013] [Indexed: 11/29/2022] Open
Abstract
To determine the type, prevalence, intensity and the potential risk factors for helminths infection harboured by primary school aged children from selected schools of Delhi, India. Stool samples collected from 347 boys and girls studying in grades I-IV (aged 5-15 years) were examined by the semi-quantitative Kato-Katz method for presence of eggs of soil-transmitted helminths. Questionnaire data on the potential risk factors, associated variables and consequences of infection were categorized as individual, household, hygiene/sanitation related and behavioural factors. Associations between infection and these factors were assessed by multiple logistic regressions. The overall prevalence of infection with any of the helminths was 29.7 %. The prevalence of single infection with Ascaris lumbricoides was 8.1 % while that of hookworm and Trichuris trichiura was 3.7 % each. Strongest predictors for the helminths presence were never deworming (OR = 1.76; 95 % CI: 1.05, 2.95), no facility for defection (OR = 4.31; 95 % CI: 1.22, 15.22), using left hand for cleaning anal region (OR = 2.01; 95 % CI: 1.18, 3.43) and not reporting pain in stomach (OR = 1.93; 95 % CI: 1.14, 3.26). Though the infection intensities were low, we highlighted some of the potential risk factors that increase the susceptibility to these infections. Periodic deworming along with improvement in hygiene and sanitation practices through concerted efforts, not only from the school infrastructure but also the community at large, will help prevent helminths transmission and reinfection.
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Affiliation(s)
- Sobhana Ranjan
- Department of Food and Nutrition, Institute of Home Economics, University of Delhi, F-4, Chaitanya Mahaprabhu Marg, Hauz Khas, New Delhi, 110 016 India ; Department of Nutrition Sciences, College of Nursing and Health Professions, Drexel University, 245 N. 15th Street, Bellet Building, Philadelphia, PA 19102 USA
| | - Santosh Jain Passi
- Department of Food and Nutrition, Institute of Home Economics, University of Delhi, F-4, Chaitanya Mahaprabhu Marg, Hauz Khas, New Delhi, 110 016 India ; NIHFW/ European Union/ Futures Group, National Institute of Health and Family Welfare, Baba Gang Nath Marg, Munirka, New Delhi, 110067 India
| | - Som Nath Singh
- Nutrition Division, Defence Institute of Physiology and Allied Sciences, DRDO, Lucknow Road, Timarpur, Delhi, 110054 India
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Vercruysse J, Albonico M, Behnke JM, Kotze AC, Prichard RK, McCarthy JS, Montresor A, Levecke B. Is anthelmintic resistance a concern for the control of human soil-transmitted helminths? Int J Parasitol Drugs Drug Resist 2011; 1:14-27. [PMID: 24533260 DOI: 10.1016/j.ijpddr.2011.09.002] [Citation(s) in RCA: 171] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2011] [Revised: 09/13/2011] [Accepted: 09/16/2011] [Indexed: 11/16/2022]
Abstract
The major human soil-transmitted helminths (STH), Ascaris lumbricoides, hookworms (Necator americanus and Ancylostoma duodenale) and Trichuris trichiura have a marked impact on human health in many parts of the world. Current efforts to control these parasites rely predominantly on periodic mass administration of anthelmintic drugs to school age children and other at-risk groups. After many years of use of these same drugs for controlling roundworms in livestock, high levels of resistance have developed, threatening the sustainability of these livestock industries in some locations. Hence, the question arises as to whether this is likely to also occur in the human STH, thereby threatening our ability to control these parasites. This is particularly important because of the recent increase in mass control programmes, relying almost exclusively on benzimidazole anthelmintics. It will be important to ensure that resistance is detected as it emerges in order to allow the implementation of mitigation strategies, such as use of drug combinations, to ensure that the effectiveness of the few existing anthelmintic drugs is preserved. In this review we address these issues by firstly examining the efficacy of anthelmintics against the human STH, and assessing whether there are any indications to date that resistance has emerged. We then consider the factors that influence the effect of current drug-use patterns in selecting for resistant parasite populations. We describe the tools currently available for resistance monitoring (field-based coprological methods), and those under development (in vitro bioassays and molecular tests), and highlight confounding factors that need to be taken into account when interpreting such resistance-monitoring data. We then highlight means to ensure that the currently available tools are used correctly, particularly with regard to study design, and we set appropriate drug-efficacy thresholds. Finally, we make recommendations for monitoring drug efficacy in the field, as components of control programmes, in order to maximise the ability to detect drug resistance, and if it arises to change control strategy and prevent the spread of resistance.
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Affiliation(s)
- Jozef Vercruysse
- Ghent University, Faculty of Veterinary Medicine, Department of Virology, Parasitology and Immunology, Laboratory of Parasitology, Merelbeke, Belgium
| | | | - Jerzy M Behnke
- School of Biology, University of Nottingham, Nottingham, United Kingdom
| | - Andrew C Kotze
- Division of Livestock Industries, Commonwealth Scientific and Industrial Research Organisation, Brisbane, Australia
| | | | - James S McCarthy
- Queensland Institute for Medical Research, University of Queensland, Herston, Australia
| | - Antonio Montresor
- Department of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Bruno Levecke
- Ghent University, Faculty of Veterinary Medicine, Department of Virology, Parasitology and Immunology, Laboratory of Parasitology, Merelbeke, Belgium
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