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Coffeng LE, Stolk WA, de Vlas SJ. Predicting the risk and speed of drug resistance emerging in soil-transmitted helminths during preventive chemotherapy. Nat Commun 2024; 15:1099. [PMID: 38321011 PMCID: PMC10847116 DOI: 10.1038/s41467-024-45027-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 01/12/2024] [Indexed: 02/08/2024] Open
Abstract
Control of soil-transmitted helminths relies heavily on regular large-scale deworming of high-risk groups (e.g., children) with benzimidazole derivatives. Although drug resistance has not yet been documented in human soil-transmitted helminths, regular deworming of cattle and sheep has led to widespread benzimidazole resistance in veterinary helminths. Here we predict the population dynamics of human soil-transmitted helminth infections and drug resistance during 20 years of regular preventive chemotherapy, using an individual-based model. With the current preventive chemotherapy strategy of mainly targeting children in schools, drug resistance may evolve in soil-transmitted helminths within a decade. More intense preventive chemotherapy strategies increase the prospects of soil-transmitted helminths elimination, but also increase the speed at which drug efficacy declines, especially when implementing community-based preventive chemotherapy (population-wide deworming). If during the last decade, preventive chemotherapy against soil-transmitted helminths has led to resistance, we may not have detected it as drug efficacy has not been structurally monitored, or incorrectly so. These findings highlight the need to develop and implement strategies to monitor and mitigate the evolution of benzimidazole resistance.
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Affiliation(s)
- Luc E Coffeng
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands.
| | - Wilma A Stolk
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Sake J de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Mrimi EC, Welsche S, Ali SM, Hattendorf J, Keiser J. Emodepside for Trichuris trichiura and Hookworm Infection. N Engl J Med 2023; 388:1863-1875. [PMID: 37195942 DOI: 10.1056/nejmoa2212825] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
BACKGROUND Current treatments for soil-transmitted helminth infections in humans have low efficacy against Trichuris trichiura. Emodepside - a drug in veterinary use and under development for the treatment of onchocerciasis in humans - is a leading therapeutic candidate for soil-transmitted helminth infection. METHODS We conducted two phase 2a, dose-ranging, randomized, controlled trials to evaluate the efficacy and safety of emodepside against T. trichiura and hookworm infections. We randomly assigned, in equal numbers, adults 18 to 45 years of age in whom T. trichiura or hookworm eggs had been detected in stool samples to receive emodepside, at a single oral dose of 5, 10, 15, 20, 25, or 30 mg; albendazole, at a single oral dose of 400 mg; or placebo. The primary outcome was the percentage of participants who were cured of T. trichiura or hookworm infection (the cure rate) with emodepside 14 to 21 days after treatment, determined with the use of the Kato-Katz thick-smear technique. Safety was assessed 3, 24, and 48 hours after the receipt of treatment or placebo. RESULTS A total of 266 persons were enrolled in the T. trichiura trial and 176 in the hookworm trial. The predicted cure rate against T. trichiura in the 5-mg emodepside group (85% [95% confidence interval {CI}, 69 to 93]; 25 of 30 participants) was higher than the predicted cure rate in the placebo group (10% [95% CI, 3 to 26]; 3 of 31 participants) and the observed cure rate in the albendazole group (17% [95% CI, 6 to 35]; 5 of 30 participants). A dose-dependent relationship was shown in participants with hookworm: the observed cure rate was 32% (95% CI, 13 to 57; 6 of 19 participants) in the 5-mg emodepside group and 95% (95% CI, 74 to 99.9; 18 of 19 participants) in the 30-mg emodepside group; the observed cure rates were 14% (95% CI, 3 to 36; 3 of 21 participants) in the placebo group and 70% (95% CI, 46 to 88; 14 of 20 participants) in the albendazole group. In the emodepside groups, headache, blurred vision, and dizziness were the most commonly reported adverse events 3 and 24 hours after treatment; the incidence of events generally increased in a dose-dependent fashion. Most adverse events were mild in severity and were self-limited; there were few moderate and no serious adverse events. CONCLUSIONS Emodepside showed activity against T. trichiura and hookworm infections. (Funded by the European Research Council; ClinicalTrials.gov number, NCT05017194.).
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Affiliation(s)
- Emmanuel C Mrimi
- From the Swiss Tropical and Public Health Institute, Allschwil, and the University of Basel, Basel - both in Switzerland (E.C.M., S.W., J.H., J.K.); and Ifakara Health Institute, Ifakara (E.C.M.), and Public Health Laboratory Ivo de Carneri, Chake Chake, Pemba (S.M.A.) - both in Tanzania
| | - Sophie Welsche
- From the Swiss Tropical and Public Health Institute, Allschwil, and the University of Basel, Basel - both in Switzerland (E.C.M., S.W., J.H., J.K.); and Ifakara Health Institute, Ifakara (E.C.M.), and Public Health Laboratory Ivo de Carneri, Chake Chake, Pemba (S.M.A.) - both in Tanzania
| | - Said M Ali
- From the Swiss Tropical and Public Health Institute, Allschwil, and the University of Basel, Basel - both in Switzerland (E.C.M., S.W., J.H., J.K.); and Ifakara Health Institute, Ifakara (E.C.M.), and Public Health Laboratory Ivo de Carneri, Chake Chake, Pemba (S.M.A.) - both in Tanzania
| | - Jan Hattendorf
- From the Swiss Tropical and Public Health Institute, Allschwil, and the University of Basel, Basel - both in Switzerland (E.C.M., S.W., J.H., J.K.); and Ifakara Health Institute, Ifakara (E.C.M.), and Public Health Laboratory Ivo de Carneri, Chake Chake, Pemba (S.M.A.) - both in Tanzania
| | - Jennifer Keiser
- From the Swiss Tropical and Public Health Institute, Allschwil, and the University of Basel, Basel - both in Switzerland (E.C.M., S.W., J.H., J.K.); and Ifakara Health Institute, Ifakara (E.C.M.), and Public Health Laboratory Ivo de Carneri, Chake Chake, Pemba (S.M.A.) - both in Tanzania
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Olliaro PL, Vaillant MT, Diawara A, Speich B, Albonico M, Utzinger J, Keiser J. Egg excretion indicators for the measurement of soil-transmitted helminth response to treatment. PLoS Negl Trop Dis 2022; 16:e0010593. [PMID: 35917364 PMCID: PMC9374261 DOI: 10.1371/journal.pntd.0010593] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Revised: 08/12/2022] [Accepted: 06/18/2022] [Indexed: 11/30/2022] Open
Abstract
Background Periodic administration of anthelmintic drugs is a cost-effective intervention for morbidity control of soil-transmitted helminth (STH) infections. However, with programs expanding, drug pressure potentially selecting for drug-resistant parasites increases. While monitoring anthelmintic drug efficacy is crucial to inform country control program strategies, different factors must be taken into consideration that influence drug efficacy and make it difficult to standardize treatment outcome measures. We aimed to identify suitable approaches to assess and compare the efficacy of different anthelmintic treatments. Methodology We built an individual participant-level database from 11 randomized controlled trials and two observational studies in which subjects received single-agent or combination therapy, or placebo. Eggs per gram of stool were calculated from egg counts at baseline and post-treatment. Egg reduction rates (ERR; based on mean group egg counts) and individual-patient ERR (iERR) were utilized to express drug efficacy and analyzed after log-transformation with a linear mixed effect model. The analyses were separated by follow-up duration (14–21 and 22–45 days) after drug administration. Principal findings The 13 studies enrolled 5,759 STH stool-positive individuals; 5,688 received active medication or placebo contributing a total of 11,103 STH infections (65% had two or three concurrent infections), of whom 3,904 (8,503 infections) and 1,784 (2,550 infections) had efficacy assessed at 14–21 days and 22–45 days post-treatment, respectively. Neither the number of helminth co-infections nor duration of follow-up affected ERR for any helminth species. The number of participants treated with single-dose albendazole was 689 (18%), with single-dose mebendazole 658 (17%), and with albendazole-based co-administrations 775 (23%). The overall mean ERR assessed by day 14–21 for albendazole and mebendazole was 94.5% and 87.4%, respectively on Ascaris lumbricoides, 86.8% and 40.8% on hookworm, and 44.9% and 23.8% on Trichuris trichiura. The World Health Organization (WHO) recommended criteria for efficacy were met in 50%, 62%, and 33% studies of albendazole for A. lumbricoides, T. trichiura, and hookworm, respectively and 25% of mebendazole studies. iERR analyses showed similar results, with cure achieved in 92% of A. lumbricoides-infected subjects treated with albendazole and 93% with mebendazole; corresponding figures for hookworm were 70% and 17%, and for T. trichiura 22% and 20%. Conclusions/significance Combining the traditional efficacy assessment using group averages with individual responses provides a more complete picture of how anthelmintic treatments perform. Most treatments analyzed fail to meet the WHO minimal criteria for efficacy based on group means. Drug combinations (i.e., albendazole-ivermectin and albendazole-oxantel pamoate) are promising treatments for STH infections. To reduce morbidity caused by parasitic worm infections, hundreds of million treatments are given to children every year through repeat cycles of single-dose deworming drugs. This strategy works, and is cost-effective. However, the downside is drug pressure that potentially selects for resistant parasites. Hence, there is a need to monitor treatment efficacy, and do so in a way that allows us to pick up early any deterioration in treatment effects. We analyzed data from 13 trials that enrolled 5,688 infected people who were given deworming drugs or a placebo, by calculating the reduction in worm egg counts in their stools from before to 14–21 and 22–45 days after treatment using different methods. We found that many people harbored more than one species of parasitic worms. Neither multiple infections, nor the intensity of infection, or whether effects were measured earlier or later, appeared to affect treatment efficacy. We also found that the most common treatments are only partially effective. The World Health Organization recommended criteria for efficacy were met in 50%, 62%, and 33% studies of albendazole for roundworm, whipworm, and hookworm, respectively and in 25% of mebendazole studies. In addition, we confirmed that combinations of albendazole-ivermectin and albendazole-oxantel pamoate are promising treatments.
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Affiliation(s)
- Piero L. Olliaro
- International Severe Acute Respiratory and Emerging Infection Consortium, Pandemic Sciences Institute, University of Oxford, Oxford, United Kingdom
| | - Michel T. Vaillant
- Centre of Competence for Methodology and Statistics, Luxembourg Institute of Health, Strassen, Luxembourg
- * E-mail:
| | - Aïssatou Diawara
- Program in Biology, Division of Science and Mathematics, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
- The Global Institute for Disease Elimination, Abu Dhabi, United Arab Emirates
| | - Benjamin Speich
- Basel Institute for Clinical Epidemiology and Biostatistics, Department of Clinical Research, University Hospital Basel, University of Basel, Basel, Switzerland
| | | | - Jürg Utzinger
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
| | - Jennifer Keiser
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
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Burden and factors associated with schistosomiasis and soil-transmitted helminth infections among school-age children in Huambo, Uige and Zaire provinces, Angola. Infect Dis Poverty 2022; 11:73. [PMID: 35752864 PMCID: PMC9233808 DOI: 10.1186/s40249-022-00975-z] [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: 01/31/2022] [Accepted: 04/17/2022] [Indexed: 12/04/2022] Open
Abstract
Background Schistosomiasis and soil-transmitted helminths (STHs) contribute high disease burdens amongst the neglected tropical diseases (NTDs) and are public health problems in Angola. This study reports the prevalence, intensity and risk factors for schistosomiasis and STH infection in Huambo, Uige and Zaire provinces, Angola, to inform a school-based preventive chemotherapy program. Methods A two-stage cluster design was used to select schools and schoolchildren to participate in parasitological and water, sanitation and hygiene (WASH) surveys across Huambo, Uige, and Zaire provinces. Point-of-care circulating cathodic antigen and urinalysis rapid diagnostic tests (RDTs) were used to determine the prevalence of Schistosoma mansoni and S. haematobium, respectively. Kato-Katz was used to identify and quantify STH species and quantify and compare with RDTs for S. mansoni. Urine filtration was used to quantify and compare with RDTs for S. haematobium. Descriptive statistics were used for prevalence and infection intensity of schistosomiasis and STH infection. Performance of RDTs was assessed through specificity and Cohen’s Kappa agreement with microscopy. A multivariate regression analysis was used to determine demographic and WASH factors associated with schistosomiasis and STH infection. Results A total 575 schools and 17,093 schoolchildren participated in the schistosomiasis survey, of which 121 schools and 3649 schoolchildren participated in the STH survey. Overall prevalence of S. mansoni was 21.2% (municipality range 0.9–74.8%) and S. haematobium 13.6% (range 0–31.2%), with an overall prevalence of schistosomiasis of 31.4% (range 5.9–77.3%). Overall prevalence of Ascaris lumbricoides was 25.1% (range 0–89.7%), hookworm 5.2% (range 0–42.6%), and Trichuris trichiura 3.6% (range 0–24.2%), with an overall prevalence of STH infection of 29.5% (range 0.8–89.7%). Ecological zone and ethnicity were factors associated with schistosomiasis and STH infection, with older age and female sex additional risk factors for S. haematobium. Conclusions Most municipalities met World Health Organization defined prevalence thresholds for a schistosomiasis preventive chemotherapy program. A STH preventive chemotherapy program is indicated for nearly all municipalities in Uige and select municipalities in Huambo and Zaire. The association between ecological zone and ethnicity with schistosomiasis and STH infection necessitates further evaluation of home and school environmental, sociodemographic and behavioural factors to inform targeted control strategies to complement preventive chemotherapy programs. Supplementary Information The online version contains supplementary material available at 10.1186/s40249-022-00975-z.
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Walker M, Cools P, Albonico M, Ame SM, Ayana M, Dana D, Keiser J, Matoso LF, Montresor A, Mekonnen Z, Corrêa-Oliveira R, Pinto SA, Sayasone S, Vercruysse J, Vlaminck J, Levecke B. Individual responses to a single oral dose of albendazole indicate reduced efficacy against soil-transmitted helminths in an area with high drug pressure. PLoS Negl Trop Dis 2021; 15:e0009888. [PMID: 34665810 PMCID: PMC8555840 DOI: 10.1371/journal.pntd.0009888] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 10/29/2021] [Accepted: 10/08/2021] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Albendazole (ALB) is administered annually to millions of children through global deworming programs targeting soil-transmitted helminths (STHs: Ascaris lumbricoides, Trichuris trichiura and hookworms, Necator americanus and Ancylostoma duodenale). However, due to the lack of large individual patient datasets collected using standardized protocols and the application of population-based statistical methods, little is known about factors that may affect individual responses to treatment. METHODOLOGY/PRINCIPAL FINDINGS We re-analyzed 645 individual patient data from three standardized clinical trials designed to assess the efficacy of a single 400 mg oral dose of ALB against STHs in schoolchildren from different study sites, each with varying history of drug pressure based on duration of mass drug administration programs: Ethiopia, low; Lao People's Democratic Republic (PDR), moderate; Pemba Island (Tanzania), high. Using a Bayesian statistical modelling approach to estimate individual responses (individual egg reduction rates, ERRi), we found that efficacy was lower in Pemba Island, particularly for T. trichiura. For this STH, the proportion of participants with a satisfactory response (ERRi ≥50%), was 65% in Ethiopia, 61% in Lao PDR but only 29% in Pemba Island. There was a significant correlation between ERRi and infection intensity prior to drug administration (ERRi decreasing as a function of increasing infection intensity). Individual age and sex also affected the drug response, but these were of negligible clinical significance and not consistent across STHs and study sites. CONCLUSIONS/SIGNIFICANCE We found decreased efficacy of ALB against all the STHs analyzed in Pemba Island (Tanzania), an area with high drug pressure. This does not indicate causality, as this association may also be partially explained by differences in infection intensity prior to drug administration. Notwithstanding, our results indicate that without alternative treatment regimens, program targets will not be achievable on Pemba Island because of inadequate efficacy of ALB. TRIAL REGISTRATION The study was registered on Clinicaltrials.gov (ID: NCT03465488) on March 7, 2018.
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Affiliation(s)
- Martin Walker
- Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, United Kingdom
- London Centre for Neglected Tropical Disease Research, Imperial College London, London, United Kingdom
- * E-mail: (MW); (BL)
| | - Piet Cools
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
| | - Marco Albonico
- Center for Tropical Diseases, Sacro Cuore Don Calabria Hospital, Negrar, Italy
- Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - Shaali M. Ame
- Laboratory Division, Public Health Laboratory-Ivo de Carneri, Chake Chake, United Republic of Tanzania
| | - Mio Ayana
- Jimma University Institute of Health, Jimma University, Jimma, Ethiopia
| | - Daniel Dana
- Jimma University Institute of Health, Jimma University, Jimma, Ethiopia
| | - Jennifer Keiser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Leonardo F. Matoso
- Laboratory of Molecular and Cellular Immunology, Research Center René Rachou—FIOCRUZ, Belo Horizonte, Brazil
- Nursing school, Federal University of Minas Gerais, Brazil
| | - Antonio Montresor
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Zeleke Mekonnen
- Jimma University Institute of Health, Jimma University, Jimma, Ethiopia
| | - Rodrigo Corrêa-Oliveira
- Laboratory of Molecular and Cellular Immunology, Research Center René Rachou—FIOCRUZ, Belo Horizonte, Brazil
| | - Simone A, Pinto
- Laboratory of Molecular and Cellular Immunology, Research Center René Rachou—FIOCRUZ, Belo Horizonte, Brazil
| | - Somphou Sayasone
- Lao Tropical and Public Health Institute, Ministry of Health, Vientiane, Lao People’s Democratic Republic
| | - Jozef Vercruysse
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
| | - Johnny Vlaminck
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
| | - Bruno Levecke
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
- * E-mail: (MW); (BL)
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Coffeng LE, Levecke B, Hattendorf J, Walker M, Denwood MJ. Survey Design to Monitor Drug Efficacy for the Control of Soil-Transmitted Helminthiasis and Schistosomiasis. Clin Infect Dis 2021; 72:S195-S202. [PMID: 33906226 PMCID: PMC8201552 DOI: 10.1093/cid/ciab196] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Background Control of soil-transmitted helminthiasis and schistosomiasis relies heavily on regular preventive chemotherapy. Monitoring drug efficacy is crucial to provide early warning of treatment failures. The World Health Organization (WHO) recommends a survey design in which only egg-positive individuals are retested after treatment. Although this practice makes more efficient use of resources, it may lead to biased drug efficacy estimates. Methods We performed a simulation study to assess the potential for bias when evaluating drug efficacy using the World Health Organization–recommended survey design, and to identify alternative designs for evaluating drug efficacy that are less affected by bias. These designs were also based on selection of egg-positive individuals, but involve retesting them a second time at baseline and up to 2 times at follow-up. The utility of the different designs was compared fairly by constraining them to the same budget. Results The standard procedure of selecting egg-positive individuals can introduce a substantial positive bias in drug efficacy due to regression toward the mean, particularly when infection levels or drug efficacy are low. This bias was completely eliminated by using a second baseline sample, conditionally on the first sample being excluded from analysis. Precision of estimates can be improved by increasing the number of thick smears and/or samples per person at follow-up, despite fewer individuals being tested within the same budget. Conclusions We present optimized survey designs to monitor drug efficacy in field settings, which are highly relevant for sustained control of soil-transmitted helminths and schistosomiasis, as well as onchocerciasis and lymphatic filariasis.
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Affiliation(s)
- Luc E Coffeng
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Bruno Levecke
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
| | - Jan Hattendorf
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Martin Walker
- Department of Pathobiology and Population Sciences and London Centre for Neglected Tropical Disease Research, Royal Veterinary College , Hatfield, United Kingdom
| | - Matthew J Denwood
- Department of Veterinary and Animal Sciences, University of Copenhagen, Denmark
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Coffeng LE, Malizia V, Vegvari C, Cools P, Halliday KE, Levecke B, Mekonnen Z, Gichuki PM, Sayasone S, Sarkar R, Shaali A, Vlaminck J, Anderson RM, de Vlas SJ. Impact of Different Sampling Schemes for Decision Making in Soil-Transmitted Helminthiasis Control Programs. J Infect Dis 2021; 221:S531-S538. [PMID: 31829425 PMCID: PMC7289558 DOI: 10.1093/infdis/jiz535] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Starting and stopping preventive chemotherapy (PC) for soil-transmitted helminthiasis is typically based on the prevalence of infection as measured by Kato-Katz (KK) fecal smears. Kato-Katz-based egg counts can vary highly over repeated stool samples and smears. Consequentially, the sensitivity of KK-based surveys depends on the number of stool samples per person and the number of smears per sample. Given finite resources, collecting multiple samples and/or smears means screening fewer individuals, thereby lowering the statistical precision of prevalence estimates. Using population-level data from various epidemiological settings, we assessed the performance of different sampling schemes executed within the confines of the same budget. We recommend the use of single-slide KK for determining prevalence of moderate-to-heavy intensity infection and policy decisions for starting and continuing PC; more sensitive sampling schemes may be required for policy decisions involving stopping PC. Our findings highlight that guidelines should include specific guidance on sampling schemes.
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Affiliation(s)
- Luc E Coffeng
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Veronica Malizia
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Carolin Vegvari
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Piet Cools
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Belgium
| | - Katherine E Halliday
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Bruno Levecke
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Belgium
| | - Zeleke Mekonnen
- Jimma University Institute of Health, Jimma University, Jimma, Ethiopia
| | - Paul M Gichuki
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya
| | - Somphou Sayasone
- Lao Tropical and Public Health Institute, Ministry of Health, Vientiane, Lao People's Democratic Republic
| | - Rajiv Sarkar
- Division of Gastrointestinal Sciences, Christian Medical College, Vellore, Tamil Nadu, India
| | - Ame Shaali
- Laboratory Division, Public Health Laboratory-Ivo de Carneri, Chake Chake, United Republic of Tanzania
| | - Johnny Vlaminck
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Belgium
| | - Roy M Anderson
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Sake J de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Insights from quantitative analysis and mathematical modelling on the proposed WHO 2030 goals for soil-transmitted helminths. Gates Open Res 2019; 3:1632. [PMID: 31819925 PMCID: PMC6869437 DOI: 10.12688/gatesopenres.13077.2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2019] [Indexed: 12/20/2022] Open
Abstract
Soil-transmitted helminths (STHs) are a group of parasitic worms that infect humans, causing a wide spectrum of disease, notably anaemia, growth retardation, and delayed cognitive development. The three main STHs are
Ascaris lumbricoides,
Trichuris trichiura and hookworm (
Necator americanus and
Ancylostoma duodenale). Approximately 1.5 billion people are infected with STHs worldwide. The World Health Organization goal for 2030 is morbidity control, defined as reaching <2% prevalence of medium-to-high intensity infections in preschool-age children and school-age children (SAC). Treatment guidelines for achieving this goal have been recommended. The Neglected Tropical Diseases Modelling Consortium has developed mathematical and statistical models to quantify, predict, and evaluate the impact of control measures on STHs. These models show that the morbidity target can be achieved following current guidelines in moderate prevalence settings (20-50% in SAC). In high prevalence settings, semi-annual preventive chemotherapy (PC) ideally including adults, or at least women of reproductive age, is required. For
T. trichiura, dual therapy with albendazole and ivermectin is required. In general, stopping PC is not possible without infection resurgence, unless effective measures for improved access to water, hygiene, and sanitation have been implemented, or elimination of transmission has been achieved. Current diagnostic methods are based on egg counts in stool samples, but these are known to have poor sensitivity at low prevalence levels. A target threshold for novel, more sensitive diagnostics should be defined relative to currently preferred diagnostics (Kato-Katz). Our analyses identify the extent of systematic non-access to treatment and the individual patterns of compliance over multiple rounds of treatment as the biggest unknowns and the main impediment to reaching the target. Moreover, the link between morbidity and infection intensity has not been fully elucidated. By providing more insights on all the above, we aim to inform discussions on the goals and treatment guidelines for STHs.
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Insights from quantitative analysis and mathematical modelling on the proposed WHO 2030 goals for soil-transmitted helminths. Gates Open Res 2019; 3:1632. [DOI: 10.12688/gatesopenres.13077.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/11/2019] [Indexed: 11/20/2022] Open
Abstract
Soil-transmitted helminths (STHs) are a group of parasitic worms that infect humans, causing a wide spectrum of disease, notably anaemia, growth retardation, and delayed cognitive development. The three main STHs are Ascaris lumbricoides, Trichuris trichiura and hookworm (Necator americanus and Ancylostoma duodenale). Approximately 1.5 billion people are infected with STHs worldwide. The World Health Organization goal for 2030 is morbidity control, defined as reaching <2% prevalence of medium-to-high intensity infections in preschool-age children and school-age children (SAC). Treatment guidelines for achieving this goal have been recommended. The Neglected Tropical Diseases Modelling Consortium has developed mathematical and statistical models to quantify, predict, and evaluate the impact of control measures on STHs. These models show that the morbidity target can be achieved following current guidelines in moderate prevalence settings (20-50% in SAC). In high prevalence settings, semi-annual preventive chemotherapy (PC) ideally including adults, or at least women of reproductive age, is required. For T. trichiura, dual therapy with albendazole and ivermectin is required. In general, stopping PC is not possible without infection resurgence, unless effective measures for improved access to water, hygiene, and sanitation have been implemented, or elimination of transmission has been achieved. Current diagnostic methods are based on egg counts in stool samples, but these are known to have poor sensitivity at low prevalence levels. A target threshold for novel, more sensitive diagnostics should be defined relative to currently preferred diagnostics (Kato-Katz). Our analyses identify the extent of systematic non-access to treatment and the individual patterns of compliance over multiple rounds of treatment as the biggest unknowns and the main impediment to reaching the target. Moreover, the link between morbidity and infection intensity has not been fully elucidated. By providing more insights on all the above, we aim to inform discussions on the goals and treatment guidelines for STHs.
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Vlaminck J, Cools P, Albonico M, Ame S, Ayana M, Cringoli G, Dana D, Keiser J, Maurelli MP, Matoso LF, Montresor A, Mekonnen Z, Mirams G, Corrêa-Oliveira R, Pinto SA, Rinaldi L, Sayasone S, Thomas E, Vercruysse J, Verweij JJ, Levecke B. Therapeutic efficacy of albendazole against soil-transmitted helminthiasis in children measured by five diagnostic methods. PLoS Negl Trop Dis 2019; 13:e0007471. [PMID: 31369562 PMCID: PMC6675043 DOI: 10.1371/journal.pntd.0007471] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 05/16/2019] [Indexed: 01/15/2023] Open
Abstract
Background Preventive chemotherapy (PC) with benzimidazole drugs is the backbone of soil-transmitted helminth (STH) control programs. Over the past decade, drug coverage has increased and with it, the possibility of developing anthelmintic resistance. It is therefore of utmost importance to monitor drug efficacy. Currently, a variety of novel diagnostic methods are available, but it remains unclear whether they can be used to monitor drug efficacy. In this study, we compared the efficacy of albendazole (ALB) measured by different diagnostic methods in a head-to-head comparison to the recommended single Kato-Katz. Methods An ALB efficacy trial was performed in 3 different STH-endemic countries (Ethiopia, Lao PDR and Tanzania), each with a different PC-history. During these trials, stool samples were evaluated with Kato-Katz (single and duplicate), Mini-FLOTAC, FECPAKG2, and qPCR. The reduction rate in mean eggs per gram of stool (ERR) and mean genome equivalents / ml of DNA extract (GERR) were calculated to estimate drug efficacy. Principal findings and conclusions The results of the efficacy trials showed that none of the evaluated diagnostic methods could provide reduction rates that were equivalent to a single Kato-Katz for all STH. However, despite differences in clinical sensitivity and egg counts, they agreed in classifying efficacy according to World Health Organization (WHO) guidelines. This demonstrates that diagnostic methods for assessing drug efficacy should be validated with their intended-use in mind and that other factors like user-friendliness and costs will likely be important factors in driving the choice of diagnostics. In addition, ALB efficacy against STH infections was lower in sites with a longer history of PC. Yet, further research is needed to identify factors that contribute to this finding and to verify whether reduced efficacy can be associated with mutations in the β-tubulin gene that have previously been linked to anthelmintic resistance. Trial registration ClinicalTrials.gov NCT03465488. During the last decade, the scale of deworming programs that aim to eliminate the morbidity caused by intestinal worms has increased to a level that is unprecedented in history. It is therefore of utmost importance to monitor any change in therapeutic efficacy that may arise from emerging drug resistance. Currently, a variety of novel methods have been described, but it remains unclear whether they can be used for monitoring drug efficacy. We applied different diagnostic methods to measure the efficacy of a commonly administered drug in deworming programs in 3 countries with different historical exposure to deworming programs. Compared to the standard diagnostic method, all diagnostic methods revealed good agreement in classifying the therapeutic efficacy according to World Health Organization guidelines, despite clear differences in diagnostic performance. We also noticed that the drug efficacy was lower in countries where drug pressure has been high. However, more research is necessary to identify factors that explain this variation in drug efficacy, including but not limited to the frequency in mutations in genes that are known to be linked with anthelmintic resistance.
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Affiliation(s)
- Johnny Vlaminck
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
| | - Piet Cools
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
| | - Marco Albonico
- Center for Tropical Diseases, Sacro Cuore Don Calabria Hospital, Negrar, Italy
- Department of Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - Shaali Ame
- Laboratory Division, Public Health Laboratory-Ivo de Carneri, Chake Chake, United Republic of Tanzania
| | - Mio Ayana
- Jimma University Institute of Health, Jimma University, Jimma, Ethiopia
| | - Giuseppe Cringoli
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Naples, Italy
| | - Daniel Dana
- Jimma University Institute of Health, Jimma University, Jimma, Ethiopia
| | - Jennifer Keiser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Maria P. Maurelli
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Naples, Italy
| | - Leonardo F. Matoso
- Laboratory of Molecular and Cellular Immunology, Research Center René Rachou—FIOCRUZ, Belo Horizonte, Brazil
- Nursing school, Federal University of Minas Gerais, Brazil
| | - Antonio Montresor
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Zeleke Mekonnen
- Jimma University Institute of Health, Jimma University, Jimma, Ethiopia
| | | | - Rodrigo Corrêa-Oliveira
- Laboratory of Molecular and Cellular Immunology, Research Center René Rachou—FIOCRUZ, Belo Horizonte, Brazil
| | - Simone A. Pinto
- Laboratory of Molecular and Cellular Immunology, Research Center René Rachou—FIOCRUZ, Belo Horizonte, Brazil
| | - Laura Rinaldi
- Department of Veterinary Medicine and Animal Production, University of Naples Federico II, Naples, Italy
| | - Somphou Sayasone
- Lao Tropical and Public Health Institute, Ministry of Health, Vientiane, Lao People's Democratic Republic
| | | | - Jozef Vercruysse
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
| | - Jaco J. Verweij
- Laboratory for Medical Microbiology and Immunology, Elisabeth-TweeSteden Hospital, Tilburg, The Netherlands
| | - Bruno Levecke
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
- * E-mail:
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De Marco Verissimo C, Potriquet J, You H, McManus DP, Mulvenna J, Jones MK. Qualitative and quantitative proteomic analyses of Schistosoma japonicum eggs and egg-derived secretory-excretory proteins. Parasit Vectors 2019; 12:173. [PMID: 30992086 PMCID: PMC6469072 DOI: 10.1186/s13071-019-3403-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 03/20/2019] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Schistosome parasites lay up to a thousand eggs per day inside the veins of their mammalian hosts. The immature eggs deposited by females against endothelia of venules will embryonate within days. Approximately 30% of the eggs will migrate to the lumen of the intestine to continue the parasite life-cycle. Many eggs, however, are trapped in the liver and intestine causing the main pathology associated with schistosomiasis mansoni and japonica, the liver granulomatous response. Excretory-secretory egg proteins drive much of egg-induced pathogenesis of schistosomiasis mansoni, and Schistosoma japonicum induce a markedly distinct granulomatous response to that of S. mansoni. METHODS To explore the basis of variations in this responsiveness, we investigated the proteome of eggs of S. japonicum. Using mass spectrometry qualitative and quantitative (SWATH) analyses, we describe the protein composition of S. japonicum eggs secretory proteins (ESP), and the differential expression of proteins by fully mature and immature eggs, isolated from faeces and ex vivo adults. RESULTS Of 957 egg-related proteins identified, 95 were exclusively found in S. japonicum ESP which imply that they are accessible to host immune system effector elements. An in-silico analysis implies that ESP are able of stimulating the innate and adaptive immune system through several different pathways. While quantitative SWATH analysis revealed 124 proteins that are differentially expressed by mature and immature S. japonicum eggs, illuminating some important aspects of eggs biology and infection, we also show that mature eggs are more likely than immature eggs to stimulate host immune responses. CONCLUSIONS Here we present a list of potential targets that can be used to develop better strategies to avoid severe morbidity during S. japonicum infection, as well as improving diagnosis, treatment and control of schistosomiasis japonica.
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Affiliation(s)
- Carolina De Marco Verissimo
- School of Veterinary Science, The University of Queensland, Brisbane, QLD, Australia. .,Medical Biological Centre, Queen's University Belfast, Belfast, UK.
| | - Jeremy Potriquet
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Hong You
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Donald P McManus
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Jason Mulvenna
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Malcolm K Jones
- School of Veterinary Science, The University of Queensland, Brisbane, QLD, Australia
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Moser W, Bärenbold O, Mirams GJ, Cools P, Vlaminck J, Ali SM, Ame SM, Hattendorf J, Vounatsou P, Levecke B, Keiser J. Diagnostic comparison between FECPAKG2 and the Kato-Katz method for analyzing soil-transmitted helminth eggs in stool. PLoS Negl Trop Dis 2018; 12:e0006562. [PMID: 29864132 PMCID: PMC6002127 DOI: 10.1371/journal.pntd.0006562] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 06/14/2018] [Accepted: 05/25/2018] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Over one billion people are infected with soil-transmitted helminths (STH), i.e. Ascaris lumbricoides, hookworm and Trichuris trichiura. For estimating drug efficacy and monitoring anthelminthic drug resistance, accurate diagnostic methods are critical. FECPAKG2 is a new remote-diagnostic tool used in veterinary medicine, which produces an image of the stool sample that can be stored on an internet cloud. We compared for the first time FECPAKG2 with the recommended Kato-Katz method. METHODOLOGY/PRINCIPAL FINDINGS Two stool samples were collected from adolescent participants (age 15-18 years) at baseline and 14 to 21 days after treatment in the framework of a randomized clinical trial on Pemba Island, Tanzania. Stool samples were analyzed with different diagnostic efforts: i) one or ii) two Kato-Katz thick smears from the first sample, iii) two Kato-Katz thick smears from two samples and iv) FECPAKG2 from the first sample. Parameters were calculated based on a hierarchical Bayesian egg count model. Complete data for all diagnostic efforts were available from 615 participants at baseline and 231 hookworm-positive participants at follow-up. At baseline FECPAKG2 revealed a sensitivity of 75.6% (72.0-77.7) for detecting A. lumbricoides, 71.5% (67.4-95.3) for hookworm and 65.8% (64.9-66.2) for T. trichiura, which was significantly lower (all p<0.05) than any of the Kato-Katz methods and highly dependent on infection intensity. Despite that the egg counts based on FECPAKG2 were relatively lower compared to Kato-Katz by a ratio of 0.38 (0.32-0.43) for A. lumbricoides, 0.36 (0.33-0.40) for hookworm and 0.08 (0.07-0.09) for T. trichiura, the egg reduction rates (ERR) were correctly estimated with FECPAKG2. CONCLUSIONS/SIGNIFICANCE The sensitivity to identify any STH infection was considerably lower for FECPAKG2 compared to Kato-Katz. Following rigorous development, FECPAKG2 might be an interesting tool with unique features for epidemiological and clinical studies.
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Affiliation(s)
- Wendelin Moser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel Switzerland
- University of Basel, Basel, Switzerland
| | - Oliver Bärenbold
- University of Basel, Basel, Switzerland
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
| | | | - Piet Cools
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Johnny Vlaminck
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Said M. Ali
- Laboratory Division, Public Health Laboratory-Ivo de Carneri, Chake Chake, Tanzania
| | - Shaali M. Ame
- Laboratory Division, Public Health Laboratory-Ivo de Carneri, Chake Chake, Tanzania
| | - Jan Hattendorf
- University of Basel, Basel, Switzerland
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Penelope Vounatsou
- University of Basel, Basel, Switzerland
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Bruno Levecke
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Jennifer Keiser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel Switzerland
- University of Basel, Basel, Switzerland
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Lim MD, Brooker SJ, Belizario VY, Gay-Andrieu F, Gilleard J, Levecke B, van Lieshout L, Medley GF, Mekonnen Z, Mirams G, Njenga SM, Odiere MR, Rudge JW, Stuyver L, Vercruysse J, Vlaminck J, Walson JL. Diagnostic tools for soil-transmitted helminths control and elimination programs: A pathway for diagnostic product development. PLoS Negl Trop Dis 2018; 12:e0006213. [PMID: 29494581 PMCID: PMC5832200 DOI: 10.1371/journal.pntd.0006213] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Affiliation(s)
- Mark D. Lim
- Global Health Division, The Bill & Melinda Gates Foundation, Seattle, United States of America
- * E-mail:
| | - Simon J. Brooker
- Global Health Division, The Bill & Melinda Gates Foundation, Seattle, United States of America
| | | | | | - John Gilleard
- Faculty of Veterinary Medicine, University of Calgary, Calgary, Canada
| | - Bruno Levecke
- Faculty of Veterinary Medicine, Gent University, Merelbeke, Belgium
| | - Lisette van Lieshout
- Department of Parasitology, Leiden University Medical Center, Leiden, the Netherlands
| | - Graham F. Medley
- Department of Global Health and Development, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | | | | | - Maurice R. Odiere
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - James W. Rudge
- Department of Global Health and Development, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - Jozef Vercruysse
- Faculty of Veterinary Medicine, Gent University, Merelbeke, Belgium
| | - Johnny Vlaminck
- Faculty of Veterinary Medicine, Gent University, Merelbeke, Belgium
| | - Judd L. Walson
- Departments of Global Health, Medicine (Infectious Disease), Pediatrics and Epidemiology, University of Washington, United States of America
- Natural History Museum, London, United Kingdom
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Favero V, Frasca Candido RR, De Marco Verissimo C, Jones MK, St. Pierre TG, Lindholz CG, Da Silva VD, Morassutti AL, Graeff-Teixeira C. Optimization of the Helmintex method for schistosomiasis diagnosis. Exp Parasitol 2017; 177:28-34. [DOI: 10.1016/j.exppara.2017.04.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 03/30/2017] [Accepted: 04/18/2017] [Indexed: 11/26/2022]
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Easton AV, Oliveira RG, Walker M, O'Connell EM, Njenga SM, Mwandawiro CS, Webster JP, Nutman TB, Anderson RM. Sources of variability in the measurement of Ascaris lumbricoides infection intensity by Kato-Katz and qPCR. Parasit Vectors 2017; 10:256. [PMID: 28545561 PMCID: PMC5445470 DOI: 10.1186/s13071-017-2164-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 05/01/2017] [Indexed: 12/20/2022] Open
Abstract
Background Understanding and quantifying the sources and implications of error in the measurement of helminth egg intensity using Kato-Katz (KK) and the newly emerging “gold standard” quantitative polymerase chain reaction (qPCR) technique is necessary for the appropriate design of epidemiological studies, including impact assessments for deworming programs. Methods Repeated measurements of Ascaris lumbricoides infection intensity were made from samples collected in western Kenya using the qPCR and KK techniques. These data were combined with data on post-treatment worm expulsions. Random effects regression models were used to quantify the variability associated with different technical and biological factors for qPCR and KK diagnosis. The relative precision of these methods was compared, as was the precision of multiple qPCR replicates. Results For both KK and qPCR, intensity measurements were largely determined by the identity of the stool donor. Stool donor explained 92.4% of variability in qPCR measurements and 54.5% of observed measurement variance for KK. An additional 39.1% of variance in KK measurements was attributable to having expelled adult A. lumbricoides worms following anthelmintic treatment. For qPCR, the remaining 7.6% of variability was explained by the efficiency of the DNA extraction (2.4%), plate-to-plate variability (0.2%) and other residual factors (5%). Differences in replicate measurements by qPCR were comparatively small. In addition to KK variability based on stool donor infection levels, the slide reader was highly statistically significant, although it only explained 1.4% of the total variation. In a comparison of qPCR and KK variance to mean ratios under ideal conditions, the coefficient of variation was on average 3.6 times larger for KK highlighting increased precision of qPCR. Conclusions Person-to-person differences explain the majority of variability in egg intensity measurements by qPCR and KK, with very little additional variability explained by the technical factors associated with the practical implementation of these techniques. qPCR provides approximately 3.6 times more precision in estimating A. lumbricoides egg intensity than KK, and could potentially be made more cost-effective by testing each sample only once without diminishing the power of a study to assess population-level intensity and prevalence. Electronic supplementary material The online version of this article (doi:10.1186/s13071-017-2164-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alice V Easton
- Helminth Immunology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD, 20814, USA. .,Department of Infectious Disease Epidemiology and London Centre for Neglected Tropical Disease Research (LCNTDR), Faculty of Medicine, Imperial College London St Mary's Campus, London, W2 1PG, UK.
| | - Rita G Oliveira
- Department of Infectious Disease Epidemiology and London Centre for Neglected Tropical Disease Research (LCNTDR), Faculty of Medicine, Imperial College London St Mary's Campus, London, W2 1PG, UK
| | - Martin Walker
- Department of Infectious Disease Epidemiology and London Centre for Neglected Tropical Disease Research (LCNTDR), Faculty of Medicine, Imperial College London St Mary's Campus, London, W2 1PG, UK.,Department of Pathobiology and Population Science and London Centre for Neglected Tropical Disease Research (LCNTDR), The Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire, AL97TA, UK
| | - Elise M O'Connell
- Helminth Immunology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD, 20814, USA
| | - Sammy M Njenga
- The Eastern and Southern Africa Centre of International Parasite Control (ESACIPAC), Kenya Medical Research Institute, Nairobi, Kenya
| | - Charles S Mwandawiro
- The Eastern and Southern Africa Centre of International Parasite Control (ESACIPAC), Kenya Medical Research Institute, Nairobi, Kenya
| | - Joanne P Webster
- Department of Infectious Disease Epidemiology and London Centre for Neglected Tropical Disease Research (LCNTDR), Faculty of Medicine, Imperial College London St Mary's Campus, London, W2 1PG, UK.,Department of Pathobiology and Population Science and London Centre for Neglected Tropical Disease Research (LCNTDR), The Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire, AL97TA, UK
| | - Thomas B Nutman
- Helminth Immunology Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD, 20814, USA
| | - Roy M Anderson
- Department of Infectious Disease Epidemiology and London Centre for Neglected Tropical Disease Research (LCNTDR), Faculty of Medicine, Imperial College London St Mary's Campus, London, W2 1PG, UK
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Koukounari A, Hollingsworth TD. A strengthening evidence-base for mass deworming, but questions remain. Lancet 2017; 389:231-233. [PMID: 27979384 DOI: 10.1016/s0140-6736(16)32452-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 11/07/2016] [Indexed: 11/24/2022]
Affiliation(s)
- Artemis Koukounari
- Department of Biostatistics and Health Informatics, Institute of Psychiatry, Psychology and Neuroscience, King's College London, De Crespigny Park, London SE5 8AF, UK
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A preface on advances in diagnostics for infectious and parasitic diseases: detecting parasites of medical and veterinary importance. Parasitology 2017; 141:1781-8. [PMID: 25415359 DOI: 10.1017/s0031182014001309] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
There are many reasons why detection of parasites of medical and veterinary importance is vital and where novel diagnostic and surveillance tools are required. From a medical perspective alone, these originate from a desire for better clinical management and rational use of medications. Diagnosis can be at the individual-level, at close to patient settings in testing a clinical suspicion or at the community-level, perhaps in front of a computer screen, in classification of endemic areas and devising appropriate control interventions. Thus diagnostics for parasitic diseases has a broad remit as parasites are not only tied with their definitive hosts but also in some cases with their vectors/intermediate hosts. Application of current diagnostic tools and decision algorithms in sustaining control programmes, or in elimination settings, can be problematic and even ill-fitting. For example in resource-limited settings, are current diagnostic tools sufficiently robust for operational use at scale or are they confounded by on-the-ground realities; are the diagnostic algorithms underlying public health interventions always understood and well-received within communities which are targeted for control? Within this Special Issue (SI) covering a variety of diseases and diagnostic settings some answers are forthcoming. An important theme, however, throughout the SI is to acknowledge that cross-talk and continuous feedback between development and application of diagnostic tests is crucial if they are to be used effectively and appropriately.
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Hoekendijk DJL, Hill PC, Sowerby SJ. Rationale for Quality Assurance in Fecal Egg Monitoring of Soil-Transmitted Helminthiasis. Am J Trop Med Hyg 2016; 95:502-504. [PMID: 27352875 PMCID: PMC5014248 DOI: 10.4269/ajtmh.15-0463] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 05/05/2016] [Indexed: 01/17/2023] Open
Abstract
Substantial investment has been made into the once "neglected" tropical disease, soil-transmitted helminthiasis, and into control programs that operate within a framework of mapping baseline disease distribution, measuring the effectiveness of applied interventions, establishing when to cease drug administration, and for posttreatment evaluations. However, critical to each of these stages is the determination of helminth infection. The limitations of traditional microscope-based fecal egg diagnostics have not provided quality assurance in the monitoring of parasite disease and suboptimal treatment regimes provide for the potential development of parasite resistance to anthelmintic drugs. Improved diagnostic and surveillance tools are required to protect therapeutic effectiveness and to maintain funder confidence. Such tools may be on the horizon with emergent technologies that offer potential for enhanced visualization and quality-assured quantitation of helminth eggs.
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Affiliation(s)
| | - Philip C Hill
- Centre for Bioengineering and Nanomedicine, University of Otago, Dunedin, New Zealand
| | - Stephen J Sowerby
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
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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. ADVANCES IN PARASITOLOGY 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] [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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Albonico M, Levecke B, LoVerde PT, Montresor A, Prichard R, Vercruysse J, Webster JP. Monitoring the efficacy of drugs for neglected tropical diseases controlled by preventive chemotherapy. J Glob Antimicrob Resist 2015; 3:229-236. [PMID: 27842865 DOI: 10.1016/j.jgar.2015.08.004] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Accepted: 08/21/2015] [Indexed: 12/11/2022] Open
Abstract
In the last decade, pharmaceutical companies, governments and global health organisations under the leadership of the World Health Organization (WHO) have pledged large-scale donations of anthelmintic drugs, including ivermectin (IVM), praziquantel (PZQ), albendazole (ALB) and mebendazole (MEB). This worldwide scale-up in drug donations calls for strong monitoring systems to detect any changes in anthelmintic drug efficacy. This review reports on the outcome of the WHO Global Working Group on Monitoring of Neglected Tropical Diseases Drug Efficacy, which consists of three subgroups: (i) soil-transmitted helminthiases (ALB and MEB); (ii) onchocerciasis and lymphatic filariasis (IVM); and (iii) schistosomiasis (PZQ). Progress of ongoing work, challenges and research needs for each of the four main drugs used in helminthic preventive chemotherapy (PC) are reported, laying the ground for appropriate implementation of drug efficacy monitoring programmes under the co-ordination and guidelines of the WHO. Best practices for monitoring drug efficacy should be made available and capacity built as an integral part of neglected tropical disease (NTD) programme monitoring. Development of a disease-specific model to predict the impact of PC programmes, to detect outliers and to solicit responses is essential. Research studies on genetic polymorphisms in relation to low-efficacy phenotypes should be carried out to identify markers of putative resistance against all NTD drugs and ultimately to develop diagnostic assays. Development of combination and co-administration of NTD drugs as well as of new drug entities to boost the armamentarium of the few drugs available for NTD control and elimination should be pursued in parallel.
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Affiliation(s)
- M Albonico
- Fondazione Ivo de Carneri, via IV Marzo 14, 10122 Torino, Italy.
| | - B Levecke
- Laboratory of Parasitology, Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - P T LoVerde
- Departments of Biochemistry and Pathology, University of Texas Health Science Center, 7703 Floyd Curl Dr., MS7760, San Antonio, TX 78229-3900, USA
| | - A Montresor
- Department of Control of Neglected Tropical Diseases, World Health Organization, Avenue Appia 20, CH-1211 Geneva, Switzerland
| | - R Prichard
- Institute of Parasitology, McGill University, Macdonald Campus, 21 111 Lakeshore Road, St Anne-de-Bellevue, QC, Canada H9X 3V9
| | - J Vercruysse
- Laboratory of Parasitology, Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium
| | - J P Webster
- Department of Pathology and Pathogen Biology, Centre for Emerging, Endemic and Exotic Diseases (CEEED), Royal Veterinary College, University of London, Hawkshead Campus, North Mymms AL9 7TA, UK; Department of Infectious Disease Epidemiology, School of Public Health, St Mary's Hospital, Imperial College Faculty of Medicine, London W2 1PG, UK
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Abstract
Soil-transmitted helminths (STHs) infect over one billion people worldwide. Ascariasis may mimic a number of conditions, and individual clinical diagnosis often requires a thorough work-up. Kato-Katz thick smears are the standard detection method for Ascaris and, despite low sensitivity, are often used for mapping and monitoring and evaluation of national control programmes. Although increased sampling (number of stools) and diagnostic (number of examinations per stool) efforts can improve sensitivity, Kato-Katz is less sensitive than other microscopy methods such as FLOTAC®. Antibody-based diagnostics may be a sensitive diagnostic tool; however, their usefulness is limited to assessing transmission in areas aiming for elimination. Molecular diagnostics are highly sensitive and specific, but high costs limit their use to individual diagnosis, drug - efficacy studies and identification of Ascaris suum. Increased investments in research on Ascaris and other STHs are urgently required for the development of diagnostic assays to support efforts to reduce human suffering caused by these infections.
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Olliaro PL, Vaillant M, Diawara A, Coulibaly JT, Garba A, Keiser J, King CH, Knopp S, Landouré A, N’Goran EK, Raso G, Scherrer AU, Sousa-Figueiredo JC, Stete K, Zhou XN, Utzinger J. Toward Measuring Schistosoma Response to Praziquantel Treatment with Appropriate Descriptors of Egg Excretion. PLoS Negl Trop Dis 2015; 9:e0003821. [PMID: 26086551 PMCID: PMC4473103 DOI: 10.1371/journal.pntd.0003821] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2014] [Accepted: 05/10/2015] [Indexed: 01/05/2023] Open
Abstract
Background The control of schistosomiasis emphasizes preventive chemotherapy with praziquantel, which aims at decreasing infection intensity and thus morbidity in individuals, as well as transmission in communities. Standardizing methods to assess treatment efficacy is important to compare trial outcomes across settings, and to monitor program effectiveness consistently. We compared customary methods and looked at possible complementary approaches in order to derive suggestions for standardizing outcome measures. Methodology/Principal Findings We analyzed data from 24 studies conducted at African, Asian, and Latin American sites, enrolling overall 4,740 individuals infected with Schistosoma mansoni, S. haematobium, or S. japonicum, and treated with praziquantel at doses of 40–80 mg/kg. We found that group-based arithmetic and geometric means can be used interchangeably to express egg reduction rates (ERR) only if treatment efficacy is high (>95%). For lower levels of efficacy, ERR estimates are higher with geometric than arithmetic means. Using the distribution of individual responses in egg excretion, 6.3%, 1.7% and 4.3% of the subjects treated for S. haematobium, S. japonicum and S. mansoni infection, respectively, had no reduction in their egg counts (ERR = 0). The 5th, 10th, and 25th centiles of the subjects treated for S. haematobium had individual ERRs of 0%, 49.3%, and 96.5%; the corresponding values for S. japonicum were 75%, 99%, and 99%; and for S. mansoni 18.2%, 65.3%, and 99.8%. Using a single rather than quadruplicate Kato-Katz thick smear excluded 19% of S. mansoni-infected individuals. Whilst the effect on estimating ERR was negligible by individual studies, ERR estimates by arithmetic means were 8% lower with a single measurement. Conclusions/Significance Arithmetic mean calculations of Schistosoma ERR are more sensitive and therefore more appropriate to monitor drug performance than geometric means. However, neither are satisfactory to identify poor responders. Group-based response estimated by arithmetic mean and the distribution of individual ERRs are correlated, but the latter appears to be more apt to detect the presence and to quantitate the magnitude of suboptimal responses to praziquantel. To identify whether a person is infected with parasitic worms, stool or urine samples are examined for worm eggs. The drug praziquantel is used against the parasitic disease schistosomiasis. However, there is no definitive agreement as to how the efficacy of praziquantel is best expressed. We put together a database from various studies of the efficacy of praziquantel against schistosomiasis. Efficacy was measured using customary methods: cure rate (CR: percentage of people with eggs in their stool/urine before treatment who became egg-negative after treatment); and egg reduction rate (ERR; percentage reduction in the number of eggs in the stool/urine after treatment, where the mean number of eggs from all people treated is calculated using either geometric or arithmetic means). We found that arithmetic and geometric means can be used interchangeably only if treatment efficacy is very high; arithmetic means are more sensitive to capture drops in efficacy expressed by ERR. A valid complement for drug efficacy monitoring is to study the distribution of individual responses in egg excretion that allows identifying in a single measure both those who had an adequate response to treatment and those who respond less well; e.g., the 5% of the patients with the lowest ERRs.
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Affiliation(s)
- Piero L. Olliaro
- UNICEF/UNDP/World Bank/WHO Special Programme on Research and Training in Tropical Diseases (TDR), World Health Organization, Geneva, Switzerland
- Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- * E-mail:
| | - Michel Vaillant
- Centre of Competence for Methodology and Statistics (CCMS), Luxembourg Institute of Health (LIH), Strassen, Luxembourg
| | - Aïssatou Diawara
- Department of Biology, Division of Science and Mathematics, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
| | - Jean T. Coulibaly
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Abidjan, Côte d’Ivoire
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Amadou Garba
- University of Basel, Basel, Switzerland
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
- Réseau International Schistosomoses, Environnement, Aménagement et Lutte (RISEAL-Niger), Niamey, Niger
| | - Jennifer Keiser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Charles H. King
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, United States of America
- Schistosomiasis Consortium for Operational Research and Evaluation, University of Georgia, Athens, Georgia, United States of America
| | - Stefanie Knopp
- University of Basel, Basel, Switzerland
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
- Wolfson Wellcome Biomedical Laboratories, Department of Life Sciences, Natural History Museum, London, United Kingdom
| | - Aly Landouré
- Institut National de Recherche en Santé Publique, Bamako, Mali
| | - Eliézer K. N’Goran
- Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, Abidjan, Côte d’Ivoire
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Abidjan, Côte d’Ivoire
| | - Giovanna Raso
- University of Basel, Basel, Switzerland
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Alexandra U. Scherrer
- Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - José Carlos Sousa-Figueiredo
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Katarina Stete
- University of Basel, Basel, Switzerland
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
- Center for Infectious Diseases and Travel Medicine, Department of Medicine, University Hospital Freiburg, Freiburg im Breisgau, Germany
| | - Xiao-Nong Zhou
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, People’s Republic of China
- Key Laboratory of Parasite and Vector Biology of the Chinese Ministry of Health, WHO Collaborating Center for Malaria, Schistosomiasis and Filariasis, Shanghai, People’s Republic of China
| | - Jürg Utzinger
- University of Basel, Basel, Switzerland
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland
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Olsen A, Kinung'hi S, Magnussen P. Schistosoma mansoni infection along the coast of Lake Victoria in Mwanza region, Tanzania. Am J Trop Med Hyg 2015; 92:1240-4. [PMID: 25825388 DOI: 10.4269/ajtmh.14-0676] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 02/23/2015] [Indexed: 01/17/2023] Open
Abstract
Prevalence and intensity of Schistosoma mansoni infection according to age, sex, and occupation were investigated in 100 first-year students (aged 7-8 years), 100 schoolchildren (aged 9-12 years), and 50 adults (aged 20-55 years) from 149 villages. The schoolchildren provided three stool specimens while the rest provided only one specimen. A total of 31,865 individuals provided at least one specimen with an overall prevalence of 38.5% and geometric mean intensity of positives of 107.0 eggs per gram of feces. With the exception of first-year students, males had higher prevalence than females (P < 0.0005). Schoolchildren had higher prevalence than first-year students that again had higher prevalence than adults. There was no sex difference in intensities among the children, but adult males had higher intensities than adult females. Intensity among the children was higher than that of the adults (P < 0.0005). Prevalence was significantly higher in those having fishing as their main occupation. Three stools samples were obtained from 13,119 schoolchildren, resulting in a prevalence of 38.1% if only one sample was included, 47.5% including two samples, and 52.6% if all three samples were included.
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Affiliation(s)
- Annette Olsen
- Parasitology and Aquatic Diseases, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; National Institute for Medical Research, Mwanza Research Centre, Mwanza, Tanzania
| | - Safari Kinung'hi
- Parasitology and Aquatic Diseases, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; National Institute for Medical Research, Mwanza Research Centre, Mwanza, Tanzania
| | - Pascal Magnussen
- Parasitology and Aquatic Diseases, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; National Institute for Medical Research, Mwanza Research Centre, Mwanza, Tanzania
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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. ADVANCES IN PARASITOLOGY 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] [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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Smith JL, Sturrock HJW, Assefa L, Nikolay B, Njenga SM, Kihara J, Mwandawiro CS, Brooker SJ. Factors associated with the performance and cost-effectiveness of using lymphatic filariasis transmission assessment surveys for monitoring soil-transmitted helminths: a case study in Kenya. Am J Trop Med Hyg 2015; 92:342-353. [PMID: 25487730 PMCID: PMC4347340 DOI: 10.4269/ajtmh.14-0435] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 10/06/2014] [Indexed: 01/24/2023] Open
Abstract
Transmission assessment surveys (TAS) for lymphatic filariasis have been proposed as a platform to assess the impact of mass drug administration (MDA) on soil-transmitted helminths (STHs). This study used computer simulation and field data from pre- and post-MDA settings across Kenya to evaluate the performance and cost-effectiveness of the TAS design for STH assessment compared with alternative survey designs. Variations in the TAS design and different sample sizes and diagnostic methods were also evaluated. The district-level TAS design correctly classified more districts compared with standard STH designs in pre-MDA settings. Aggregating districts into larger evaluation units in a TAS design decreased performance, whereas age group sampled and sample size had minimal impact. The low diagnostic sensitivity of Kato-Katz and mini-FLOTAC methods was found to increase misclassification. We recommend using a district-level TAS among children 8-10 years of age to assess STH but suggest that key consideration is given to evaluation unit size.
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Affiliation(s)
- Jennifer L. Smith
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom; Global Health Group, University of California San Francisco, San Francisco, California; Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute (KEMRI), Nairobi, Kenya
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Levecke B, Montresor A, Albonico M, Ame SM, Behnke JM, Bethony JM, Noumedem CD, Engels D, Guillard B, Kotze AC, Krolewiecki AJ, McCarthy JS, Mekonnen Z, Periago MV, Sopheak H, Tchuem-Tchuenté LA, Duong TT, Huong NT, Zeynudin A, Vercruysse J. Assessment of anthelmintic efficacy of mebendazole in school children in six countries where soil-transmitted helminths are endemic. PLoS Negl Trop Dis 2014; 8:e3204. [PMID: 25299391 PMCID: PMC4191962 DOI: 10.1371/journal.pntd.0003204] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Accepted: 08/20/2014] [Indexed: 12/26/2022] Open
Abstract
Background Robust reference values for fecal egg count reduction (FECR) rates of the most widely used anthelmintic drugs in preventive chemotherapy (PC) programs for controlling soil-transmitted helminths (STHs; Ascaris lumbricoides, Trichuris trichiura, and hookworm) are still lacking. However, they are urgently needed to ensure detection of reduced efficacies that are predicted to occur due to growing drug pressure. Here, using a standardized methodology, we assessed the FECR rate of a single oral dose of mebendazole (MEB; 500 mg) against STHs in six trials in school children in different locations around the world. Our results are compared with those previously obtained for similarly conducted trials of a single oral dose of albendazole (ALB; 400 mg). Methodology The efficacy of MEB, as assessed by FECR, was determined in six trials involving 5,830 school children in Brazil, Cambodia, Cameroon, Ethiopia, United Republic of Tanzania, and Vietnam. The efficacy of MEB was compared to that of ALB as previously assessed in 8,841 school children in India and all the above-mentioned study sites, using identical methodologies. Principal Findings The estimated FECR rate [95% confidence interval] of MEB was highest for A. lumbricoides (97.6% [95.8; 99.5]), followed by hookworm (79.6% [71.0; 88.3]). For T. trichiura, the estimated FECR rate was 63.1% [51.6; 74.6]. Compared to MEB, ALB was significantly more efficacious against hookworm (96.2% [91.1; 100], p<0.001) and only marginally, although significantly, better against A. lumbricoides infections (99.9% [99.0; 100], p = 0.012), but equally efficacious for T. trichiura infections (64.5% [44.4; 84.7], p = 0.906). Conclusions/Significance A minimum FECR rate of 95% for A. lumbricoides, 70% for hookworm, and 50% for T. trichiura is expected in MEB-dependent PC programs. Lower FECR results may indicate the development of potential drug resistance. Soil-transmitted helminths (STHs; roundworms, whipworms, and hookworms) infect millions of children in sub-tropical and tropical countries, resulting in malnutrition, growth stunting, intellectual retardation, and cognitive deficits. To fight against STH, large-scale deworming programs are implemented in which anthelmintic drugs (either albendazole (ALB) or mebendazole (MEB)) are administered. Currently, these large-scale programs are intensifying, highlighting the need to closely monitor the efficacy of anthelmintic drugs to detect changes in drug efficacy that may arise through the evolution of anthelmintic drug resistance in the parasites. We have previously defined the minimum expected efficacy of ALB based on the fecal egg count reduction (FECR) rate, but these reference values are lacking for MEB. Therefore, we therefore evaluated the FECR rate of MEB against STHs in six STH endemic countries. In addition, we compared the results of the FECR rate for MEB with those we obtained previously for ALB. The results confirm that MEB treatment was highly efficacious against roundworms, and to a lesser extend against hookworms, but not against whipworms. Compared to ALB, MEB is less efficacious against hookworm, but equally efficacious against roundworms and whipworms. Based on this study we propose the minimum expected FECR rate for MEB-dependent large-scale deworming programs.
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Affiliation(s)
- Bruno Levecke
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
- * E-mail:
| | - Antonio Montresor
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | | | - Shaali M. Ame
- Public Health Laboratory-Ivo de Carneri, Chake Chake, United Republic of Tanzania
| | - Jerzy M. Behnke
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Jeffrey M. Bethony
- Microbiology, Immunology, and Tropical Medicine, George Washington University Medical Center, Washington, D.C., United States of America
| | - Calvine D. Noumedem
- Centre for Schistosomiasis and Parasitology, University of Yaoundé I, Yaoundé, Cameroon
| | - Dirk Engels
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | | | - Andrew C. Kotze
- Division of Animal, Food and Health Sciences, Commonwealth Scientific and Industrial Research Organisation, St. Lucia, Australia
| | - Alejandro J. Krolewiecki
- Instituto de Investigaciones en Enfermedades Tropicales, Universidad Nacional de Salta/CONICET, Oran, Argentina
| | - James S. McCarthy
- Queensland Institute for Medical Research, University of Queensland, Brisbane, Australia
| | - Zeleke Mekonnen
- Department of Medical Laboratory Sciences and Pathology, Jimma University, Jimma, Ethiopia
| | - Maria V. Periago
- Instituto René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Brazil
| | - Hem Sopheak
- Clinical Laboratory, Pasteur Institute, Phnom Penh, Cambodia
| | | | - Tran Thanh Duong
- Department of Parasitology, National Institute of Malariology, Parasitology and Entomology, Ha Noi, Vietnam
| | - Nguyen Thu Huong
- Department of Parasitology, National Institute of Malariology, Parasitology and Entomology, Ha Noi, Vietnam
| | - Ahmed Zeynudin
- Department of Medical Laboratory Sciences and Pathology, Jimma University, Jimma, Ethiopia
| | - Jozef Vercruysse
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
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Diagnostics for schistosomiasis in Africa and Arabia: a review of present options in control and future needs for elimination. Parasitology 2014; 141:1947-61. [PMID: 25158604 DOI: 10.1017/s0031182014001152] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Within the World Health Organization 2012-2020 roadmap for control and elimination of schistosomiasis, the scale-up of mass drug administration with praziquantel is set to change the epidemiological landscape across Africa and Arabia. Central in measuring progress is renewed emphasis upon diagnostics which operate at individual, community and environmental levels by assessing reductions in disease, infections and parasite transmission. However, a fundamental tension is revealed between levels for present diagnostic tools, and methods applied in control settings are not necessarily adequate for application in elimination scenarios. Indeed navigating the transition from control to elimination needs careful consideration and planning. In the present context of control, we review current options for diagnosis of schistosomiasis at different levels, highlighting several strengths and weaknesses therein. Future challenges in elimination are raised and we propose that more cost-effective diagnostics and clinical staging algorithms are needed. Using the Kingdom of Saudi Arabia as a contemporary example, embedding new diagnostic methods within the primary care health system is discussed with reference to both urogenital and intestinal schistosomiasis.
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Nikolay B, Brooker SJ, Pullan RL. Sensitivity of diagnostic tests for human soil-transmitted helminth infections: a meta-analysis in the absence of a true gold standard. Int J Parasitol 2014; 44:765-74. [PMID: 24992655 PMCID: PMC4186778 DOI: 10.1016/j.ijpara.2014.05.009] [Citation(s) in RCA: 176] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 05/19/2014] [Accepted: 05/20/2014] [Indexed: 01/19/2023]
Abstract
A Bayesian latent class meta-analysis of diagnostic tests for soil-transmitted helminths was performed. Overall sensitivity of evaluated diagnostic tests was low. Test performance was strongly influenced by intensity of infection. FLOTAC method sensitivity was highest overall and in both intensity groups. The performance of the Kato-Katz method in high intensity settings was acceptable.
Reliable, sensitive and practical diagnostic tests are an essential tool in disease control programmes for mapping, impact evaluation and surveillance. To provide a robust global assessment of the relative performance of available diagnostic tools for the detection of soil-transmitted helminths, we conducted a meta-analysis comparing the sensitivities and the quantitative performance of the most commonly used copro-microscopic diagnostic methods for soil-transmitted helminths, namely Kato-Katz, direct microscopy, formol-ether concentration, McMaster, FLOTAC and Mini-FLOTAC. In the absence of a perfect reference standard, we employed a Bayesian latent class analysis to estimate the true, unobserved sensitivity of compared diagnostic tests for each of the soil-transmitted helminth species Ascaris lumbricoides, Trichuris trichiura and the hookworms. To investigate the influence of varying transmission settings we subsequently stratified the analysis by intensity of infection. Overall, sensitivity estimates varied between the different methods, ranging from 42.8% for direct microscopy to 92.7% for FLOTAC. The widely used double slide Kato-Katz method had a sensitivity of 74–95% for the three soil-transmitted helminth species at high infection intensity, however sensitivity dropped to 53–80% in low intensity settings, being lowest for hookworm and A. lumbricoides. The highest sensitivity, overall and in both intensity groups, was observed for the FLOTAC method, whereas the sensitivity of the Mini-FLOTAC method was comparable with the Kato-Katz method. FLOTAC average egg count estimates were significantly lower compared with Kato-Katz, while the compared McMaster counts varied. In conclusion, we demonstrate that the Kato-Katz and Mini-FLOTAC methods had comparable sensitivities. We further show that test sensitivity of the Kato-Katz method is reduced in low transmission settings.
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Affiliation(s)
- Birgit Nikolay
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, WC1E 7HT London, United Kingdom.
| | - Simon J Brooker
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, WC1E 7HT London, United Kingdom
| | - Rachel L Pullan
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, WC1E 7HT London, United Kingdom
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