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Tallima H, Tadros MM, El Ridi R. Differential protective impact of peptide vaccine formulae targeting the lung- and liver-stage of challenge Schistosoma mansoni infection in mice. Acta Trop 2024; 254:107208. [PMID: 38621620 DOI: 10.1016/j.actatropica.2024.107208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 02/11/2024] [Accepted: 04/05/2024] [Indexed: 04/17/2024]
Abstract
The study aimed to elicit protective immune responses against murine schistosomiasis mansoni at the parasite lung- and liver stage. Two peptides showing amino acid sequence similarity to gut cysteine peptidases, which induce strong memory immune effectors in the liver, were combined with a peptide based on S. mansoni thioredoxin peroxidase (TPX), a prominent lung-stage schistosomula excretory-secretory product, and alum as adjuvant. Only one of the 2 cysteine peptidases-based peptides in a multiple antigenic peptide construct (MAP-3 and MAP-4) appeared to adjuvant protective immune responses induced by the TPX peptide in a MAP form. Production of TPX MAP-specific IgG1 serum antibodies, and increase in lung interleukin-1 (IL-1), uric acid, and reactive oxygen species (ROS) content were associated with significant (P < 0.05) 50 % reduction in recovery of lung-stage larvae. Increase in lung triglycerides and cholesterol levels appeared to provide the surviving worms with nutrients necessary for a stout double lipid bilayer barrier at the parasite-host interface. Surviving worms-released products elicited memory responses to the MAP-3 immunogen, including production of specific IgG1 antibodies and increase in liver IL-33 and ROS. Reduction in challenge worm burden recorded 45 days post infection did not exceed 48 % associated with no differences in parasite egg counts in the host liver and small intestine compared to unimmunized adjuvant control mice. Alum adjuvant assisted the second peptide, MAP-4, in production of IgG1, IgG2a, IgG2b and IgA specific antibodies and increase in liver ROS, but with no protective potential, raising doubt about the necessity of adjuvant addition. Accordingly, different vaccine formulas containing TPX MAP and 1, 2 or 3 cysteine peptidases-derived peptides with or without alum were used to immunize parallel groups of mice. Compared to unimmunized control mice, significant (P < 0.05 to < 0.005) 22 to 54 % reduction in worm burden was recorded in the different groups associated with insignificant changes in parasite egg output. The results together indicated that a schistosomiasis vaccine able to entirely prevent disease and halt its transmission still remains elusive.
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Affiliation(s)
- Hatem Tallima
- Zoology Department, Faculty of Science, Cairo University, Giza 12613, Egypt; Department of Chemistry, School of Sciences and Engineering, American University in Cairo, New Cairo 11835, Cairo, Egypt.
| | - Menerva M Tadros
- Department of Parasitology, Theodore Bilharz Research Institute, Warrak El-Hadar, Imbaba, Giza 12411, Egypt
| | - Rashika El Ridi
- Zoology Department, Faculty of Science, Cairo University, Giza 12613, Egypt
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Human Schistosomiasis Vaccines as Next Generation Control Tools. Trop Med Infect Dis 2023; 8:tropicalmed8030170. [PMID: 36977171 PMCID: PMC10054132 DOI: 10.3390/tropicalmed8030170] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 02/24/2023] [Accepted: 03/06/2023] [Indexed: 03/18/2023] Open
Abstract
Human schistosomiasis remains one of the most important yet neglected tropical diseases, with the latest estimates from the Global Burden of Disease Study indicating that over 140 million people are infected with schistosomes [...]
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Kura K, Ayabina D, Hollingsworth TD, Anderson RM. Determining the optimal strategies to achieve elimination of transmission for Schistosoma mansoni. Parasit Vectors 2022; 15:55. [PMID: 35164842 PMCID: PMC8842958 DOI: 10.1186/s13071-022-05178-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 01/25/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND In January 2021, the World Health Organization published the 2021-2030 roadmap for the control of neglected tropical diseases (NTDs). The goal for schistosomiasis is to achieve elimination as a public health problem (EPHP) and elimination of transmission (EOT) in 78 and 25 countries (by 2030), respectively. Mass drug administration (MDA) of praziquantel continues to be the main strategy for control and elimination. However, as there is limited availability of praziquantel, it is important to determine what volume of treatments are required, who should be targeted and how frequently treatment must be administered to eliminate either transmission or morbidity caused by infection in different endemic settings with varied transmission intensities. METHODS AND RESULTS: In this paper, we employ two individual-based stochastic models of schistosomiasis transmission developed independently by the Imperial College London (ICL) and University of Oxford (SCHISTOX) to determine the optimal treatment strategies to achieve EOT. We find that treating school-age children (SAC) only is not sufficient to achieve EOT within a feasible time frame, regardless of the transmission setting and observed age-intensity of infection profile. Both models show that community-wide treatment is necessary to interrupt transmission in all endemic settings with low, medium and high pristine transmission intensities. CONCLUSIONS The required MDA coverage level to achieve either transmission or morbidity elimination depends on the prevalence prior to the start of treatment and the burden of infection in adults. The higher the worm burden in adults, the higher the coverage levels required for this age category through community-wide treatment programmes. Therefore, it is important that intensity and prevalence data are collected in each age category, particularly from SAC and adults, so that the correct coverage level can be calculated and administered.
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Affiliation(s)
- Klodeta Kura
- grid.512598.2London Centre for Neglected Tropical Disease Research, London, UK ,grid.7445.20000 0001 2113 8111Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary’s Campus, Imperial College London, London, UK ,grid.14105.310000000122478951MRC Centre for Global Infectious Disease Analysis, London, UK
| | - Diepreye Ayabina
- grid.4991.50000 0004 1936 8948Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, OX3 7LF UK
| | - T. Deirdre Hollingsworth
- grid.4991.50000 0004 1936 8948Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, OX3 7LF UK
| | - Roy M. Anderson
- grid.512598.2London Centre for Neglected Tropical Disease Research, London, UK ,grid.7445.20000 0001 2113 8111Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary’s Campus, Imperial College London, London, UK ,grid.14105.310000000122478951MRC Centre for Global Infectious Disease Analysis, London, UK ,grid.35937.3b0000 0001 2270 9879The DeWorm3 Project, The Natural History Museum of London, London, UK
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Kura K, Hardwick RJ, Truscott JE, Anderson RM. What is the impact of acquired immunity on the transmission of schistosomiasis and the efficacy of current and planned mass drug administration programmes? PLoS Negl Trop Dis 2021; 15:e0009946. [PMID: 34851952 PMCID: PMC8635407 DOI: 10.1371/journal.pntd.0009946] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 10/23/2021] [Indexed: 11/18/2022] Open
Abstract
Schistosomiasis causes severe morbidity in many countries with endemic infection with the schistosome digenean parasites in Africa and Asia. To control and eliminate the disease resulting from infection, regular mass drug administration (MDA) is used, with a focus on school-aged children (SAC; 5-14 years of age). In some high transmission settings, the World Health Organization (WHO) also recommends the inclusion of at-risk adults in MDA treatment programmes. The question of whether ecology (age-dependant exposure) or immunity (resistance to reinfection), or some combination of both, determines the form of observed convex age-intensity profile is still unresolved, but there is a growing body of evidence that the human hosts acquire some partial level of immunity after a long period of repeated exposure to infection. In the majority of past research modelling schistosome transmission and the impact of MDA programmes, the effect of acquired immunity has not been taken into account. Past work has been based on the assumption that age-related contact rates generate convex horizontal age-intensity profiles. In this paper, we use an individual based stochastic model of transmission and MDA impact to explore the effect of acquired immunity in defined MDA programmes. Compared with scenarios with no immunity, we find that acquired immunity makes the MDA programme less effective with a slower decrease in the prevalence of infection. Therefore, the time to achieve morbidity control and elimination as a public health problem is longer than predicted by models with just age-related exposure and no build-up of immunity. The level of impact depends on the baseline prevalence prior to treatment (the magnitude of the basic reproductive number R0) and the treatment frequency, among other factors. We find that immunity has a larger impact within moderate to high transmission settings such that it is very unlikely to achieve morbidity and transmission control employing current MDA programmes.
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Affiliation(s)
- Klodeta Kura
- London Centre for Neglected Tropical Disease Research, London, United Kingdom
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary’s Campus, Imperial College London, London, United Kingdom
- MRC Centre for Global Infectious Disease Analysis, London, United Kingdom
| | - Robert J. Hardwick
- London Centre for Neglected Tropical Disease Research, London, United Kingdom
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary’s Campus, Imperial College London, London, United Kingdom
- MRC Centre for Global Infectious Disease Analysis, London, United Kingdom
- The DeWorm3 Project, The Natural History Museum of London, London, United Kingdom
| | - James E. Truscott
- London Centre for Neglected Tropical Disease Research, London, United Kingdom
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary’s Campus, Imperial College London, London, United Kingdom
- MRC Centre for Global Infectious Disease Analysis, London, United Kingdom
- The DeWorm3 Project, The Natural History Museum of London, London, United Kingdom
| | - Roy M. Anderson
- London Centre for Neglected Tropical Disease Research, London, United Kingdom
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary’s Campus, Imperial College London, London, United Kingdom
- MRC Centre for Global Infectious Disease Analysis, London, United Kingdom
- The DeWorm3 Project, The Natural History Museum of London, London, United Kingdom
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Ayabina D, Kura K, Toor J, Graham M, Anderson RM, Hollingsworth TD. Maintaining Low Prevalence of Schistosoma mansoni: Modeling the Effect of Less Frequent Treatment. Clin Infect Dis 2021; 72:S140-S145. [PMID: 33909064 PMCID: PMC8201569 DOI: 10.1093/cid/ciab246] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND The World Health Organization previously set goals of controlling morbidity due to schistosomiasis by 2020 and attaining elimination as a public health problem (EPHP) by 2025 (now adjusted to 2030 in the new neglected tropical diseases roadmap). As these milestones are reached, it is important that programs reassess their treatment strategies to either maintain these goals or progress from morbidity control to EPHP and ultimately to interruption of transmission. In this study, we consider different mass drug administration (MDA) strategies to maintain the goals. METHODS We used 2 independently developed, individual-based stochastic models of schistosomiasis transmission to assess the optimal treatment strategy of a multiyear program to maintain the morbidity control and the EPHP goals. RESULTS We found that, in moderate-prevalence settings, once the morbidity control and EPHP goals are reached it may be possible to maintain the goals using less frequent MDAs than those that are required to achieve the goals. On the other hand, in some high-transmission settings, if control efforts are reduced after achieving the goals, particularly the morbidity control goal, there is a high chance of recrudescence. CONCLUSIONS To reduce the risk of recrudescence after the goals are achieved, programs have to re-evaluate their strategies and decide to either maintain these goals with reduced efforts where feasible or continue with at least the same efforts required to reach the goals.
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Affiliation(s)
- Diepreye Ayabina
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
| | - Klodeta Kura
- London Centre for Neglected Tropical Disease Research, London, United Kingdom.,Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary's Campus, Imperial College London, London, United Kingdom.,MRC Centre for Global Infectious Disease Analysis, London,United Kingdom
| | - Jaspreet Toor
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom.,MRC Centre for Global Infectious Disease Analysis, London,United Kingdom.,Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA), School of Public Health, Imperial College London, London, United Kingdom
| | - Matt Graham
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom.,Centre for Mathematical Modelling of Infectious Disease, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Roy M Anderson
- London Centre for Neglected Tropical Disease Research, London, United Kingdom.,Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary's Campus, Imperial College London, London, United Kingdom.,MRC Centre for Global Infectious Disease Analysis, London,United Kingdom.,The DeWorm3 Project, The Natural History Museum of London, London, United Kingdom
| | - T Deirdre Hollingsworth
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
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Kura K, Ayabina D, Toor J, Hollingsworth TD, Anderson RM. Disruptions to schistosomiasis programmes due to COVID-19: an analysis of potential impact and mitigation strategies. Trans R Soc Trop Med Hyg 2021; 115:236-244. [PMID: 33515038 PMCID: PMC7928593 DOI: 10.1093/trstmh/traa202] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 10/28/2020] [Accepted: 01/03/2021] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND The 2030 goal for schistosomiasis is elimination as a public health problem (EPHP), with mass drug administration (MDA) of praziquantel to school-age children (SAC) as a central pillar of the strategy. However, due to coronavirus disease 2019, many mass treatment campaigns for schistosomiasis have been halted, with uncertain implications for the programmes. METHODS We use mathematical modelling to explore how postponement of MDA and various mitigation strategies affect achievement of the EPHP goal for Schistosoma mansoni and S. haematobium. RESULTS For both S. mansoni and S. haematobium in moderate- and some high-prevalence settings, the disruption may delay the goal by up to 2 y. In some high-prevalence settings, EPHP is not achievable with current strategies and so the disruption will not impact this. Here, increasing SAC coverage and treating adults can achieve the goal. The impact of MDA disruption and the appropriate mitigation strategy varies according to the baseline prevalence prior to treatment, the burden of infection in adults and the stage of the programme. CONCLUSIONS Schistosomiasis MDA programmes in medium- and high-prevalence areas should restart as soon as is feasible and mitigation strategies may be required in some settings.
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Affiliation(s)
- Klodeta Kura
- London Centre for Neglected Tropical Disease Research, London, UK.,Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary's Campus, Imperial College London, London, UK.,MRC Centre for Global Infectious Disease Analysis
| | - Diepreye Ayabina
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford OX3 7LF, UK
| | - Jaspreet Toor
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford OX3 7LF, UK
| | - T Deirdre Hollingsworth
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford OX3 7LF, UK
| | - Roy M Anderson
- London Centre for Neglected Tropical Disease Research, London, UK.,Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary's Campus, Imperial College London, London, UK.,MRC Centre for Global Infectious Disease Analysis.,DeWorm3 Project, Natural History Museum of London, London, UK
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7
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Kura K, Hardwick RJ, Truscott JE, Toor J, Hollingsworth TD, Anderson RM. The impact of mass drug administration on Schistosoma haematobium infection: what is required to achieve morbidity control and elimination? Parasit Vectors 2020; 13:554. [PMID: 33203467 PMCID: PMC7672840 DOI: 10.1186/s13071-020-04409-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 10/21/2020] [Indexed: 12/01/2022] Open
Abstract
Background Schistosomiasis remains an endemic parasitic disease causing much morbidity and, in some cases, mortality. The World Health Organization (WHO) has outlined strategies and goals to combat the burden of disease caused by schistosomiasis. The first goal is morbidity control, which is defined by achieving less than 5% prevalence of heavy intensity infection in school-aged children (SAC). The second goal is elimination as a public health problem (EPHP), achieved when the prevalence of heavy intensity infection in SAC is reduced to less than 1%. Mass drug administration (MDA) of praziquantel is the main strategy for control. However, there is limited availability of praziquantel, particularly in Africa where there is high prevalence of infection. It is therefore important to explore whether the WHO goals can be achieved using the current guidelines for treatment based on targeting SAC and, in some cases, adults. Previous modelling work has largely focused on Schistosoma mansoni, which in advance cases can cause liver and spleen enlargement. There has been much less modelling of the transmission of Schistosoma haematobium, which in severe cases can cause kidney damage and bladder cancer. This lack of modelling has largely been driven by limited data availability and challenges in interpreting these data. Results In this paper, using an individual-based stochastic model and age-intensity profiles of S. haematobium from two different communities, we calculate the probability of achieving the morbidity and EPHP goals within 15 years of treatment under the current WHO treatment guidelines. We find that targeting SAC only can achieve the morbidity goal for all transmission settings, regardless of the burden of infection in adults. The EPHP goal can be achieved in low transmission settings, but in some moderate to high settings community-wide treatment is needed. Conclusions We show that the key determinants of achieving the WHO goals are the precise form of the age-intensity of infection profile and the baseline SAC prevalence. Additionally, we find that the higher the burden of infection in adults, the higher the chances that adults need to be included in the treatment programme to achieve EPHP.
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Affiliation(s)
- Klodeta Kura
- London Centre for Neglected Tropical Disease Research, London, UK. .,Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary's Campus, Imperial College London, London, UK. .,MRC Centre for Global Infectious Disease Analysis, London, UK.
| | - Robert J Hardwick
- London Centre for Neglected Tropical Disease Research, London, UK.,Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary's Campus, Imperial College London, London, UK.,MRC Centre for Global Infectious Disease Analysis, London, UK.,The DeWorm3 Project, The Natural History Museum of London, London, UK
| | - James E Truscott
- London Centre for Neglected Tropical Disease Research, London, UK.,Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary's Campus, Imperial College London, London, UK.,MRC Centre for Global Infectious Disease Analysis, London, UK.,The DeWorm3 Project, The Natural History Museum of London, London, UK
| | - Jaspreet Toor
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, OX3 7LF, UK
| | - T Deirdre Hollingsworth
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, OX3 7LF, UK
| | - Roy M Anderson
- London Centre for Neglected Tropical Disease Research, London, UK.,Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine, St Mary's Campus, Imperial College London, London, UK.,MRC Centre for Global Infectious Disease Analysis, London, UK.,The DeWorm3 Project, The Natural History Museum of London, London, UK
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