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Jones BP, Kozel K, Alonte AJI, Llanes KKR, Juhász A, Chaudhry U, Roose S, Geldhof P, Belizario VY, Nejsum P, Stothard JR, LaCourse EJ, van Vliet AHM, Paller VGV, Betson M. Worldwide absence of canonical benzimidazole resistance-associated mutations within β-tubulin genes from Ascaris. Parasit Vectors 2024; 17:225. [PMID: 38755679 PMCID: PMC11098727 DOI: 10.1186/s13071-024-06306-5] [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: 03/08/2024] [Accepted: 04/24/2024] [Indexed: 05/18/2024] Open
Abstract
BACKGROUND The giant roundworm Ascaris is an intestinal nematode, causing ascariasis by infecting humans and pigs worldwide. Recent estimates suggest that Ascaris infects over half a billion people, with chronic infections leading to reduced growth and cognitive ability. Ascariasis affects innumerable pigs worldwide and is known to reduce production yields via decreased growth and condemnation of livers. The predominant anthelminthic drugs used to treat ascariasis are the benzimidazoles. Benzimidazoles interact with β-tubulins and block their function, and several benzimidazole resistance-associated mutations have been described in the β-tubulins of ruminant nematodes. Recent research on ascarids has shown that these canonical benzimidazole resistance-associated mutations are likely not present in the β-tubulins of Ascaris, Ascaridia or Parascaris, even in phenotypically resistant populations. METHODS To further determine the putative absence of key β-tubulin polymorphisms, we screened two β-tubulin isotypes of Ascaris, highly expressed in adult worms. Using adult and egg samples of Ascaris obtained from pigs and humans worldwide, we performed deep amplicon sequencing to look for canonical resistance-associated mutations in Ascaris β-tubulins. Subsequently, we examined these data in closer detail to study the population dynamics of Ascaris and genetic diversity within the two isotypes and tested whether genotypes appeared to partition across human and pig hosts. RESULTS In the 187 isolates, 69 genotypes were found, made up of eight haplotypes of β-tubulin isotype A and 20 haplotypes of isotype B. Single nucleotide polymorphisms were seen at 14 and 37 positions for β-tubulin isotype A and isotype B, respectively. No evidence of any canonical benzimidazole resistance-associated mutations was found in either human- or pig-derived Ascaris isolates. There was, however, a difference in the genetic diversity of each isotype and distribution of β-tubulin genotypes between human- and pig-derived Ascaris. Statistical tests of population differentiation show significant differences (p < 0.001) between pig- and human-derived worms; however, more diversity was seen between worms from different populations than worms from different hosts. CONCLUSIONS Our work suggests an absence of canonical β-tubulin mutations within Ascaris, but alternative modes of anthelminthic resistance may emerge necessitating continued genetic scrutiny alongside monitoring of drug efficacy.
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Affiliation(s)
- Ben P Jones
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, University of Surrey, Guildford, GU2 7AL, UK
| | - Kezia Kozel
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, University of Surrey, Guildford, GU2 7AL, UK
| | - Allen Jethro I Alonte
- Institute of Biological Sciences, University of the Philippines Los Baños, Laguna, Philippines
| | - Kennesa Klariz R Llanes
- Institute of Biological Sciences, University of the Philippines Los Baños, Laguna, Philippines
| | - Alexandra Juhász
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
- Institute of Medical Microbiology, Semmelweis University, Budapest, Hungary
| | - Umer Chaudhry
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, University of Surrey, Guildford, GU2 7AL, UK
- School of Veterinary Medicine, St. George's University, True Blue, West Indies, Grenada
| | - Sara Roose
- Department of Translational Physiology, Infectiology and Public Health, Ghent University, Merelbeke, Belgium
| | - Peter Geldhof
- Department of Translational Physiology, Infectiology and Public Health, Ghent University, Merelbeke, Belgium
| | - Vicente Y Belizario
- Department of Parasitology, College of Public Health, University of the Philippines Manila, Manila, Philippines
| | - Peter Nejsum
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - J Russell Stothard
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - E James LaCourse
- Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Arnoud H M van Vliet
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, University of Surrey, Guildford, GU2 7AL, UK
| | - Vachel Gay V Paller
- Institute of Biological Sciences, University of the Philippines Los Baños, Laguna, Philippines
| | - Martha Betson
- Department of Comparative Biomedical Sciences, School of Veterinary Medicine, University of Surrey, Guildford, GU2 7AL, UK.
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Rayment Gomez S, Maddren R, Liyew EF, Chernet M, Anjulo U, Tamiru A, Tollera G, Tasew G, Mengistu B, Collyer B, Forbes K, Anderson R. Spatial heterogeneity in mass drug administration from a longitudinal epidemiological study assessing transmission interruption of soil transmitted helminths in the Wolaita zone of southern Ethiopia (Geshiyaro Project). PLoS Negl Trop Dis 2024; 18:e0011947. [PMID: 38330143 PMCID: PMC10880954 DOI: 10.1371/journal.pntd.0011947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 02/21/2024] [Accepted: 01/28/2024] [Indexed: 02/10/2024] Open
Abstract
OBJECTIVES Deworming programmes of soil-transmitted helminths are generally monitored and evaluated by aggregating drug coverage and infection levels at a district level. However, heterogeneity in drug coverage at finer spatial scales means indicators may remain above thresholds for elimination as a public health problem or of transmission in some areas. This paper aims to highlight the misleading information that aggregating data at larger spatial scales can have for programme decision making. METHODS Drug coverage data from the Geshiyaro project were compared at two spatial scales with reference to the World Health Organisation's targets. District (woreda) and village (kebele) level were compared. The association between infection levels and drug coverage was analysed by fitting a weighted least-squares function to the mean intensity of infection (eggs per gram of faeces) against drug coverage. RESULTS The data show clearly that when the evaluation of coverage is aggregated to the district level, information on heterogeneity at a finer spatial scale is lost. Infection intensity decreases significantly (p = 0.0023) with increasing drug coverage. CONCLUSION Aggregating data at large spatial scales can result in prematurely ceasing deworming, prompting rapid infection bounce-back. There is a strong need to define context-specific spatial scales for monitoring and evaluating intervention programmes.
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Affiliation(s)
- Santiago Rayment Gomez
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Faculty of Medicine, St Marys Campus, Imperial College London, London, United Kingdom
| | - Rosie Maddren
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Faculty of Medicine, St Marys Campus, Imperial College London, London, United Kingdom
| | - Ewnetu Firdawek Liyew
- Bacterial, Parasitic and Zoonotic Disease Research Directorate, Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Melkie Chernet
- Bacterial, Parasitic and Zoonotic Disease Research Directorate, Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Ufaysa Anjulo
- Disease Prevention and Health Promotion Core Process, Ministry of Health, Wolaita, Ethiopia
| | - Adugna Tamiru
- Disease Prevention and Health Promotion Core Process, Ministry of Health, Wolaita, Ethiopia
| | - Getachew Tollera
- Bacterial, Parasitic and Zoonotic Disease Research Directorate, Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Geremew Tasew
- Bacterial, Parasitic and Zoonotic Disease Research Directorate, Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Birhan Mengistu
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Faculty of Medicine, St Marys Campus, Imperial College London, London, United Kingdom
| | - Benjamin Collyer
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Faculty of Medicine, St Marys Campus, Imperial College London, London, United Kingdom
| | - Kathryn Forbes
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Faculty of Medicine, St Marys Campus, Imperial College London, London, United Kingdom
| | - Roy Anderson
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Faculty of Medicine, St Marys Campus, Imperial College London, London, United Kingdom
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Maddren R, Anderson RM. Measuring heterogeneities in soil-transmitted helminth transmission and control. Trends Parasitol 2024; 40:45-59. [PMID: 38087679 DOI: 10.1016/j.pt.2023.11.003] [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: 09/18/2023] [Revised: 11/08/2023] [Accepted: 11/08/2023] [Indexed: 01/06/2024]
Abstract
The global effort over the past decade to control soil-transmitted helminths (STH) has resulted in communities with endemic infection reaching low prevalence levels suitable for the validation of elimination as a public health problem (EPHP), defined by the World Health Organisation (WHO) as <2% of infections classified as moderate or heavy intensity. The spatial scale in which this is validated is currently undefined. As the burden of STH infection decreases, the degree of aggregation of infection within individuals in a population increases. Identifying these remaining pockets of infection requires fine-scale monitoring and evaluation (M&E) programmes that are rarely implemented within current national neglected tropical disease (NTD) control. This review examines various heterogeneities that characterise the epidemiology of STH infections, and discusses their impact on control policy formulation.
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Affiliation(s)
- Rosie Maddren
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London, UK.
| | - Roy M Anderson
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London, UK
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Forbes K, Basáñez MG, Hollingsworth TD, Anderson RM. Introduction to the special issue: challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220272. [PMID: 37598699 PMCID: PMC10440167 DOI: 10.1098/rstb.2022.0272] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 07/20/2023] [Indexed: 08/22/2023] Open
Abstract
Twenty neglected tropical diseases (NTDs) are currently prioritised by the World Health Organization for eradication, elimination as a public health problem, elimination of transmission or control by 2030. This issue celebrates progress made since the 2012 London Declaration on NTDs and discusses challenges currently faced to achieve these goals. It comprises 14 contributions spanning NTDs tackled by intensified disease management to those addressed by preventive chemotherapy. Although COVID-19 negatively affected NTD programmes, it also served to spur new multisectoral approaches to strengthen school-based health systems. The issue highlights the needs to improve impact survey design, evaluate new diagnostics, understand the consequences of heterogeneous prevalence and human movement, the potential impact of alternative treatment strategies and the importance of zoonotic transmission. This article is part of the theme issue 'Challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.
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Affiliation(s)
- Kathryn Forbes
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London W2 1PG, UK
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London W2 1PG, UK
- MRC Centre for Global Infectious Disease Analysis (MRC GIDA), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London W2 1PG, UK
| | | | - Roy M. Anderson
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London W2 1PG, UK
- MRC Centre for Global Infectious Disease Analysis (MRC GIDA), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, Imperial College London, London W2 1PG, UK
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