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Borlase A, Prada JM, Crellen T. Modelling morbidity for neglected tropical diseases: the long and winding road from cumulative exposure to long-term pathology. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220279. [PMID: 37598702 PMCID: PMC10440174 DOI: 10.1098/rstb.2022.0279] [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: 01/14/2023] [Accepted: 07/13/2023] [Indexed: 08/22/2023] Open
Abstract
Reducing the morbidities caused by neglected tropical diseases (NTDs) is a central aim of ongoing disease control programmes. The broad spectrum of pathogens under the umbrella of NTDs lead to a range of negative health outcomes, from malnutrition and anaemia to organ failure, blindness and carcinogenesis. For some NTDs, the most severe clinical manifestations develop over many years of chronic or repeated infection. For these diseases, the association between infection and risk of long-term pathology is generally complex, and the impact of multiple interacting factors, such as age, co-morbidities and host immune response, is often poorly quantified. Mathematical modelling has been used for many years to gain insights into the complex processes underlying the transmission dynamics of infectious diseases; however, long-term morbidities associated with chronic or cumulative exposure are generally not incorporated into dynamic models for NTDs. Here we consider the complexities and challenges for determining the relationship between cumulative pathogen exposure and morbidity at the individual and population levels, drawing on case studies for trachoma, schistosomiasis and foodborne trematodiasis. We explore potential frameworks for explicitly incorporating long-term morbidity into NTD transmission models, and consider the insights such frameworks may bring in terms of policy-relevant projections for the elimination era. 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)
- Anna Borlase
- Department of Biology, University of Oxford, Oxford OX1 3SZ, UK
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford OX3 7LF, UK
| | - Joaquin M. Prada
- Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Thomas Crellen
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford OX3 7LF, UK
- School of Biodiversity, One Health & Veterinary Medicine, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK
- Wellcome Centre for Integrative Parasitology, Sir Graeme Davies Building, University of Glasgow, Glasgow G12 8TA, UK
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Whitson CC, Nute AW, Hailemariam B, Deathe AR, Astale T, Ayele Z, Gessese D, Sata E, Zerihun M, Melak B, Haile M, Zeru T, Getnet B, Wondimteka B, Kabtu E, Getachew H, Shibiru M, Bayecha S, Aragie S, Wittberg DM, Tadesse Z, Callahan EK, Keenan JD, Admassu F, Nash SD. Photographic grading for trachoma diagnosis within trachoma impact surveys in Amhara region, Ethiopia. Trans R Soc Trop Med Hyg 2023; 117:111-117. [PMID: 36162054 PMCID: PMC9890315 DOI: 10.1093/trstmh/trac090] [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: 01/28/2022] [Revised: 05/03/2022] [Accepted: 09/06/2022] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND As countries reach the trachoma elimination threshold and cases of trachomatous inflammation follicular (TF) become rare, it becomes difficult to train survey graders to recognize clinical signs. We assess the use of photography as a grading tool, the efficiency of an in-country grading center and the comparability of field and photographic grading. METHODS During January-February 2017 surveys in Amhara, Ethiopia, field graders assessed TF, trachomatous inflammation intense (TI) and trachomatous scarring (TS). Photographs were taken from each conjunctiva and later graded at the Gondar Grading Center (GGC) at the University of Gondar in Amhara. Two trained ophthalmology residents graded each set of photographs and a third grader provided an adjudicating grade when needed. RESULTS A total of 4953 photographs of 2477 conjunctivae from 1241 participants in 10 communities were graded over 5 d at the GGC. Six examined participants were not photographed. Agreement between field and photographic grades were for TF: percent agreement (PA) 96.7%, κ=0.70 (95% confidence interval [CI] 0.64 to 0.77; for TI: PA 94.7%, κ=0.32 (95% CI 0.20 to 0.43); and for TS: PA 83.5%, κ=0.22 (95% CI 0.15 to 0.29). CONCLUSIONS Conjunctival photography may be a solution for programs near the elimination threshold where there are few available community cases for training field graders.
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Affiliation(s)
| | - Andrew W Nute
- Trachoma Control Program, The Carter Center, Atlanta, GA, USA
| | | | - Andrew R Deathe
- Trachoma Control Program, The Carter Center, Atlanta, GA, USA
| | - Tigist Astale
- Trachoma Control Program, The Carter Center, Addis Ababa, Ethiopia
| | - Zebene Ayele
- Trachoma Control Program, The Carter Center, Addis Ababa, Ethiopia
| | - Demelash Gessese
- Trachoma Control Program, The Carter Center, Addis Ababa, Ethiopia
| | - Eshetu Sata
- Trachoma Control Program, The Carter Center, Addis Ababa, Ethiopia
| | - Mulat Zerihun
- Trachoma Control Program, The Carter Center, Addis Ababa, Ethiopia
| | - Berhanu Melak
- Trachoma Control Program, The Carter Center, Addis Ababa, Ethiopia
| | - Mahteme Haile
- Research and Technology Transfer Directorate, Amhara Public Health Institute, Bahir Dar, Ethiopia
| | - Taye Zeru
- Research and Technology Transfer Directorate, Amhara Public Health Institute, Bahir Dar, Ethiopia
| | - Banchalem Getnet
- Department of Ophthalmology, University of Gondar, Gondar, Ethiopia
| | - Bilen Wondimteka
- Department of Ophthalmology, University of Gondar, Gondar, Ethiopia
| | - Endale Kabtu
- Department of Ophthalmology, University of Gondar, Gondar, Ethiopia
| | - Habib Getachew
- Department of Ophthalmology, University of Gondar, Gondar, Ethiopia
| | - Meskerem Shibiru
- Department of Ophthalmology, University of Gondar, Gondar, Ethiopia
| | - Social Bayecha
- Department of Ophthalmology, University of Gondar, Gondar, Ethiopia
| | - Solomon Aragie
- Trachoma Control Program, The Carter Center, Addis Ababa, Ethiopia
| | - Dionna M Wittberg
- Francis I. Proctor Foundation, University of California, San Francisco, San Francisco, CA, USA
| | - Zerihun Tadesse
- Trachoma Control Program, The Carter Center, Addis Ababa, Ethiopia
| | | | - Jeremy D Keenan
- Francis I. Proctor Foundation, University of California, San Francisco, San Francisco, CA, USA
| | - Fisseha Admassu
- Department of Ophthalmology, University of Gondar, Gondar, Ethiopia
| | - Scott D Nash
- Trachoma Control Program, The Carter Center, Atlanta, GA, USA
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Lynch KD, Apadinuwe SC, Lambert SB, Hillgrove T, Starr M, Catlett B, Ware RS, Cama A, Webster S, Harding-Esch EM, Bakhtiari A, Butcher R, Cunningham P, Martin D, Gwyn S, Solomon AW, Garabwan C, Kaldor JM, Vaz Nery S. A national survey integrating clinical, laboratory, and WASH data to determine the typology of trachoma in Nauru. PLoS Negl Trop Dis 2022; 16:e0010275. [PMID: 35439248 PMCID: PMC9017947 DOI: 10.1371/journal.pntd.0010275] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 02/24/2022] [Indexed: 11/23/2022] Open
Abstract
Background The epidemiology of trachoma in several Pacific Islands differs from other endemic settings, in that there is a high prevalence of clinical signs of trachoma, particularly trachomatous inflammation—follicular (TF), but few cases of trichiasis and limited evidence of ocular chlamydial infection. This so-called “Pacific enigma” has led to uncertainty regarding the appropriate public health response. In 2019 alongside Nauru’s national trachoma population survey, we performed bacteriological and serological assessments of children to better understand the typology of trachoma and to determine whether there is a need for trachoma interventions. Methods We used two-stage cluster sampling, examining residents aged ≥1 year and collecting household-level water, sanitation, and hygiene (WASH) variables. Children aged 1–9 years provided conjunctival swabs and finger-prick dried blood spots to investigate the presence of Chlamydia trachomatis nucleic acid and anti-Pgp3 antibodies, respectively. Principal Findings In 818 participants aged 1–9 years, the age-adjusted TF prevalence was 21.8% (95% CI 15.2–26.2%); ocular C. trachomatis prevalence was 34.5% (95% CI 30.6–38.9), and anti-Pgp3 antibody prevalence was 32.1% (95% CI 28.4%–36.3%). The age- and gender-adjusted prevalence of trichiasis in ≥15-year-olds was 0.3% (95% CI 0.00–0.85), but no individual with trichiasis had trachomatous scarring (TS). Multivariable analysis showed an association between age and both TF (OR per year of age 1.3 [95% CI 1.2–1.4]) and anti-Pgp3 positivity (OR 1.2 [95% CI 1.2–1.3]). There were high rates of access to water and sanitation and no WASH variable was associated with the presence of TF. Conclusions TF, nucleic acid, and age-specific antibody prevalence collectively indicate that high levels of C. trachomatis transmission among children present a high risk of ocular damage due to trachoma. The absence of trichiasis with trachomatous scarring suggest a relatively recent increase in transmission intensity. In contrast to several neighbouring Pacific Island nations, Nauruan children are heavily affected by active trachoma and the cause is ocular infection with C. trachomatis. Comprehensive public health intervention to control trachoma in Nauru is required. The use of laboratory markers for current and previous C. trachomatis infection should be considered in baseline trachoma prevalence surveys as we approach global elimination of trachoma, and in settings with inconsistent findings during previous screening exercises.
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Affiliation(s)
- Kathleen D. Lynch
- UQ Centre for Clinical Research, University of Queensland, Brisbane, Australia
- * E-mail:
| | | | - Stephen B. Lambert
- UQ Centre for Clinical Research, University of Queensland, Brisbane, Australia
- National Centre for Immunisation Research and Surveillance, Westmead, New South Wales, Australia
| | | | - Mitchell Starr
- NSW State Reference Laboratory for HIV, St Vincent’s Centre for Applied Medical Research, St Vincent’s Hospital, Sydney, Australia
| | - Beth Catlett
- NSW State Reference Laboratory for HIV, St Vincent’s Centre for Applied Medical Research, St Vincent’s Hospital, Sydney, Australia
| | - Robert S. Ware
- Menzies Health Institute Queensland and School of Medicine, Griffith University, Brisbane, Australia
| | | | - Sara Webster
- The Fred Hollows Foundation, Melbourne, Australia
| | - Emma M. Harding-Esch
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Ana Bakhtiari
- International Trachoma Initiative, Task Force for Global Health, Decatur, Georgia, United States of America
| | - Robert Butcher
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Philip Cunningham
- NSW State Reference Laboratory for HIV, St Vincent’s Centre for Applied Medical Research, St Vincent’s Hospital, Sydney, Australia
| | - Diana Martin
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Sarah Gwyn
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Anthony W. Solomon
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | | | - John M. Kaldor
- The Kirby Institute, University of New South Wales, Sydney, Australia
| | - Susana Vaz Nery
- The Kirby Institute, University of New South Wales, Sydney, Australia
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