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Arsevska E, Hengl T, Singleton DA, Noble PJM, Caminade C, Eneanya OA, Jones PH, Medlock JM, Hansford KM, Bonannella C, Radford AD. Risk factors for tick attachment in companion animals in Great Britain: a spatiotemporal analysis covering 2014-2021. Parasit Vectors 2024; 17:29. [PMID: 38254168 PMCID: PMC10804489 DOI: 10.1186/s13071-023-06094-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Accepted: 12/11/2023] [Indexed: 01/24/2024] Open
Abstract
BACKGROUND Ticks are an important driver of veterinary health care, causing irritation and sometimes infection to their hosts. We explored epidemiological and geo-referenced data from > 7 million electronic health records (EHRs) from cats and dogs collected by the Small Animal Veterinary Surveillance Network (SAVSNET) in Great Britain (GB) between 2014 and 2021 to assess the factors affecting tick attachment in an individual and at a spatiotemporal level. METHODS EHRs in which ticks were mentioned were identified by text mining; domain experts confirmed those with ticks on the animal. Tick presence/absence records were overlaid with a spatiotemporal series of climate, environment, anthropogenic and host distribution factors to produce a spatiotemporal regression matrix. An ensemble machine learning spatiotemporal model was used to fine-tune hyperparameters for Random Forest, Gradient-boosted Trees and Generalized Linear Model regression algorithms, which were then used to produce a final ensemble meta-learner to predict the probability of tick attachment across GB at a monthly interval and averaged long-term through 2014-2021 at a spatial resolution of 1 km. Individual host factors associated with tick attachment were also assessed by conditional logistic regression on a matched case-control dataset. RESULTS In total, 11,741 consultations were identified in which a tick was recorded. The frequency of tick records was low (0.16% EHRs), suggesting an underestimation of risk. That said, increased odds for tick attachment in cats and dogs were associated with younger adult ages, longer coat length, crossbreeds and unclassified breeds. In cats, males and entire animals had significantly increased odds of recorded tick attachment. The key variables controlling the spatiotemporal risk for tick attachment were climatic (precipitation and temperature) and vegetation type (Enhanced Vegetation Index). Suitable areas for tick attachment were predicted across GB, especially in forests and grassland areas, mainly during summer, particularly in June. CONCLUSIONS Our results can inform targeted health messages to owners and veterinary practitioners, identifying those animals, seasons and areas of higher risk for tick attachment and allowing for more tailored prophylaxis to reduce tick burden, inappropriate parasiticide treatment and potentially TBDs in companion animals and humans. Sentinel networks like SAVSNET represent a novel complementary data source to improve our understanding of tick attachment risk for companion animals and as a proxy of risk to humans.
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Affiliation(s)
- Elena Arsevska
- Unit for Animals, Health, Territories, Risks and Ecosystems (UMR ASTRE), French Agricultural Research Centre for International Development (CIRAD), 34980, Montferrier-sur-Lez, France.
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, CH64 7TE, Neston, UK.
| | - Tomislav Hengl
- OpenGeoHub Foundation, 6708 PW, Wageningen, The Netherlands
| | - David A Singleton
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, CH64 7TE, Neston, UK
| | - Peter-John M Noble
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, CH64 7TE, Neston, UK
| | - Cyril Caminade
- Earth System Physics Department, Abdus Salam International Centre for Theoretical Physics (ICTP), 34151, Trieste, Italy
| | - Obiora A Eneanya
- Health Programs, The Carter Center, 30307, Atlanta, Georgia, USA
| | - Philip H Jones
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, CH64 7TE, Neston, UK
| | - Jolyon M Medlock
- Medical Entomology and Zoonoses Ecology, UK Health Security Agency, SP4 0JG, Salisbury, UK
- NIHR Health Protection Research Unit in Environmental Change and Health, WC1E 7HT, London, UK
| | - Kayleigh M Hansford
- Medical Entomology and Zoonoses Ecology, UK Health Security Agency, SP4 0JG, Salisbury, UK
- NIHR Health Protection Research Unit in Environmental Change and Health, WC1E 7HT, London, UK
| | - Carmelo Bonannella
- OpenGeoHub Foundation, 6708 PW, Wageningen, The Netherlands
- Laboratory of Geo-information Science and Remote Sensing, Wageningen University & Research, 6708 PB, Wageningen, The Netherlands
| | - Alan D Radford
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, CH64 7TE, Neston, UK
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Eneanya OA, Reimer LJ, Fischer PU, Weil GJ. Geospatial modelling of lymphatic filariasis and malaria co-endemicity in Nigeria. Int Health 2023; 15:566-572. [PMID: 37096453 PMCID: PMC10472894 DOI: 10.1093/inthealth/ihad029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 04/03/2023] [Accepted: 04/04/2023] [Indexed: 04/26/2023] Open
Abstract
BACKGROUND Lymphatic filariasis (LF) and malaria are important vector-borne diseases that are co-endemic throughout Nigeria. These infections are transmitted by the same mosquito vector species in Nigeria and their transmission is similarly influenced by climate and sociodemographic factors. The goal of this study was to assess the relationship between the geospatial distribution of both infections in Nigeria to better coordinate interventions. METHODS We used national survey data for malaria from the Demographic and Health Survey dataset and site-level LF mapping data from the Nigeria Lymphatic Filariasis Control Programme together with a suite of predictive climate and sociodemographic factors to build geospatial machine learning models. These models were then used to produce continuous gridded maps of both infections throughout Nigeria. RESULTS The R2 values for the LF and malaria models were 0.68 and 0.59, respectively. Also, the correlation between pairs of observed and predicted values for LF and malaria models were 0.69 (95% confidence interval [CI] 0.61 to 0.79; p<0.001) and 0.61 (95% CI 0.52 to 0.71; p<0.001), respectively. However, we observed a very weak positive correlation between overall overlap of LF and malaria distribution in Nigeria. CONCLUSIONS The reasons for this counterintuitive relationship are unclear. Differences in transmission dynamics of these parasites and vector competence may contribute to differences in the distribution of these co-endemic diseases.
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Affiliation(s)
- Obiora A Eneanya
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63108, USA
| | - Lisa J Reimer
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - Peter U Fischer
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63108, USA
| | - Gary J Weil
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63108, USA
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Stolk WA, Coffeng LE, Bolay FK, Eneanya OA, Fischer PU, Hollingsworth TD, Koudou BG, Méité A, Michael E, Prada JM, Caja Rivera RM, Sharma S, Touloupou P, Weil GJ, de Vlas SJ. Comparing antigenaemia- and microfilaraemia as criteria for stopping decisions in lymphatic filariasis elimination programmes in Africa. PLoS Negl Trop Dis 2022; 16:e0010953. [PMID: 36508458 PMCID: PMC9779720 DOI: 10.1371/journal.pntd.0010953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 12/22/2022] [Accepted: 11/14/2022] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Mass drug administration (MDA) is the main strategy towards lymphatic filariasis (LF) elimination. Progress is monitored by assessing microfilaraemia (Mf) or circulating filarial antigenaemia (CFA) prevalence, the latter being more practical for field surveys. The current criterion for stopping MDA requires <2% CFA prevalence in 6- to 7-year olds, but this criterion is not evidence-based. We used mathematical modelling to investigate the validity of different thresholds regarding testing method and age group for African MDA programmes using ivermectin plus albendazole. METHODOLGY/PRINCIPAL FINDINGS We verified that our model captures observed patterns in Mf and CFA prevalence during annual MDA, assuming that CFA tests are positive if at least one adult worm is present. We then assessed how well elimination can be predicted from CFA prevalence in 6-7-year-old children or from Mf or CFA prevalence in the 5+ or 15+ population, and determined safe (>95% positive predictive value) thresholds for stopping MDA. The model captured trends in Mf and CFA prevalences reasonably well. Elimination cannot be predicted with sufficient certainty from CFA prevalence in 6-7-year olds. Resurgence may still occur if all children are antigen-negative, irrespective of the number tested. Mf-based criteria also show unfavourable results (PPV <95% or unpractically low threshold). CFA prevalences in the 5+ or 15+ population are the best predictors, and post-MDA threshold values for stopping MDA can be as high as 10% for 15+. These thresholds are robust for various alternative assumptions regarding baseline endemicity, biological parameters and sampling strategies. CONCLUSIONS/SIGNIFICANCE For African areas with moderate to high pre-treatment Mf prevalence that have had 6 or more rounds of annual ivermectin/albendazole MDA with adequate coverage, we recommend to adopt a CFA threshold prevalence of 10% in adults (15+) for stopping MDA. This could be combined with Mf testing of CFA positives to ensure absence of a significant Mf reservoir for transmission.
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Affiliation(s)
- Wilma A. Stolk
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
- * E-mail:
| | - Luc E. Coffeng
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Fatorma K. Bolay
- National Public Health Institute of Liberia (NPHIL), Monrovia, Liberia
| | - Obiora A. Eneanya
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Peter U. Fischer
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - T. Déirdre Hollingsworth
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
| | - Benjamin G. Koudou
- Centre Suisse de Recherches Scientifiques en Côte d’Ivoire, Abidjan, Abidjan, Côte d’Ivoire
- Laboratoire de Cytologie et Biologie Animale, UFR Science de la Nature, Université Nangui Abrogoua Abidjan, Abidjan, Côte d’Ivoire
| | - Aboulaye Méité
- Programme National de Lutte contre les Maladies Tropicales Négligées à Chimiothérapie Préventive, Abidjan, Côte d’Ivoire
| | - Edwin Michael
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, Florida, United States of America
| | - Joaquin M. Prada
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Rocio M. Caja Rivera
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, Florida, United States of America
| | - Swarnali Sharma
- Department of Biological Sciences, University of Notre Dame, South Bend, Indiana, United States of America
- Christian Medical College, IDA Scudder Rd, Vellore, Tamil Nadu, India
| | - Panayiota Touloupou
- Department of Statistics, University of Warwick, Coventry, United Kingdom
- School of Mathematics, University of Birmingham, Birmingham, United Kingdom
| | - Gary J. Weil
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Sake J. de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Ekpo UF, Eneanya OA, Nwankwo EN, Soneye IY, Weil GJ, Fischer PU, Nwaorgu OC. Persistence of onchocerciasis in villages in Enugu and Ogun states in Nigeria following many rounds of mass distribution of ivermectin. BMC Infect Dis 2022; 22:832. [PMID: 36357828 PMCID: PMC9650792 DOI: 10.1186/s12879-022-07811-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 10/27/2022] [Indexed: 11/11/2022] Open
Abstract
Background Onchocerciasis is endemic in most local government areas (LGAs) in Enugu and Ogun states. Most meso- and hyper-endemic LGAs have received many rounds of ivermectin mass drug administration (MDA). This study aimed to determine the current prevalence of onchocerciasis in villages in Enugu and Ogun states that were formerly highly endemic and to assess progress toward elimination of the infection in areas believed to be at high risk for persistence. Methods Cross-sectional community surveys were conducted 8 to 12 months after the last round of MDA in 16 villages (6 in Enugu state and 10 in Ogun state) in individuals aged ≥ 18 years. Study participants were examined for the presence of palpable subcutaneous nodules. Skin snips from the posterior iliac crests were used to assess microfiladermia (Mf) prevalence and density. Results 643 subjects were palpated for nodules and 627 individuals (225 in Enugu state; 402 in Ogun state) provided skin snips. Nodule prevalence in the study villages ranged from 42 to 66.7% in Enugu state and from 0 to 25.0% in Ogun state. Mf prevalence in the Enugu and Ogun study villages ranged from 32 to 51.1% and 0 to 28.6%, respectively. Geometric mean skin Mf density in surveyed Enugu state villages ranged between 1 and 3.1 Mf/mg; these values were < 1 Mf/mg in all but one community in Ogun state villages. Conclusion Results from this study show that onchocerciasis persists in adults in many villages in Enugu and Ogun states despite many prior rounds of ivermectin MDA. Prevalence was higher in villages surveyed in Enugu than in Ogun. Low Mf densities suggest the MDA program is working well to reduce disease, but more time will be required to reach the elimination goal. Supplementary Information The online version contains supplementary material available at 10.1186/s12879-022-07811-7.
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Eneanya OA, Gankpala L, Goss CW, Momolu AT, Nyan ES, Gray EB, Fischer K, Curtis K, Bolay FK, Weil GJ, Fischer PU. Community-based trial assessing the impact of annual versus semiannual mass drug administration with ivermectin plus albendazole and praziquantel on helminth infections in northwestern Liberia. Acta Trop 2022; 231:106437. [PMID: 35405102 PMCID: PMC9168441 DOI: 10.1016/j.actatropica.2022.106437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 03/10/2022] [Accepted: 03/28/2022] [Indexed: 11/30/2022]
Abstract
Mass drug administration (MDA) with ivermectin plus albendazole was more effective for clearing bancroftian filariasis than it was for onchocerciasis or hookworm. Semiannual MDA was no more effective than annual MDA for reducing prevalences of W. bancrofti, O. volvulus, or hookworm infections. Decreases in bancroftian filariasis prevalence were achieved despite unavoidable interruptions in our study related to the 2014 West Africa Ebola epidemic and the 2020 SARS-CoV-2 pandemic. Neglected Tropical Disease elimination programs in areas coendemic for lymphatic filariasis and onchocerciasis should focus on delivering high quality annual MDA with high coverage and compliance and not try to stretch limited resources to deliver semiannual MDA. MDA with praziquantel had little impact on Schistosoma mansoni infection in the heavily infected area.
We assessed the impact of three annual vs five semiannual rounds of mass drug administration (MDA) with ivermectin plus albendazole followed by praziquantel for the control or elimination of lymphatic filariasis (LF), onchocerciasis, soil-transmitted helminth (STH) infections and schistosomiasis in Lofa County, Liberia. The study started in 2012 and was interrupted in 2014 during the Ebola virus outbreak. Repeated cross-sectional surveys were conducted in individuals 5 years and older to measure infection markers. Wuchereria bancrofti antigenemia prevalences decreased from 12.5 to 1.2% (90% reduction) and from 13.6 to 4.2% (69% reduction) one year after three rounds of annual or five rounds of semiannual MDA, respectively. Mixed effects logistic regression models showed decreases in odds of antigenemia positivity were 91 and 74% at that time in the annual and semiannual treatment zones, respectively (p < 0.001). Semiannual MDA was slightly more effective for reducing Onchocerca volvulus microfiladermia prevalence and at follow-up 3 were 74% (from 14.4 to 3.7%) and 83% (from 23.6 to 4.5%) in the annual and semiannual treatment zones, respectively. Both treatment schedules had similar beneficial effects on hookworm prevalence. Thus, annual and semiannual MDA with ivermectin and albendazole had similar beneficial impacts on LF, onchocerciasis, and STH in this setting. In contrast, MDA with praziquantel had little impact on hyperendemic Schistosoma mansoni in the study area. Results from a long-term follow-up survey showed that improvements in infection parameters were sustained by routine annual MDA provided by the Liberian Ministry of Health after our study endpoint.
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Affiliation(s)
- Obiora A Eneanya
- Department of Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, MO, United States
| | - Lincoln Gankpala
- Division of Public Health and Medical Research, National Public Health Institute of Liberia, Charlesville, Liberia
| | - Charles W Goss
- Division of Biostatistics, Washington University School of Medicine, St. Louis, MO, United States
| | - Aaron T Momolu
- Division of Public Health and Medical Research, National Public Health Institute of Liberia, Charlesville, Liberia
| | - Enoch S Nyan
- Division of Public Health and Medical Research, National Public Health Institute of Liberia, Charlesville, Liberia
| | - Emmanuel B Gray
- Ministry of Health of Liberia, C.B. Dunbar Hospital, Gbarnga, Liberia
| | - Kerstin Fischer
- Department of Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, MO, United States
| | - Kurt Curtis
- Department of Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, MO, United States
| | - Fatorma K Bolay
- Division of Public Health and Medical Research, National Public Health Institute of Liberia, Charlesville, Liberia
| | - Gary J Weil
- Department of Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, MO, United States
| | - Peter U Fischer
- Department of Medicine, Infectious Diseases Division, Washington University School of Medicine, St. Louis, MO, United States.
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Eneanya OA, Gankpala L, Goss CW, Bolay FK, Weil GJ, Fischer PU. Impact of Annual versus Semiannual Mass Drug Administration with Ivermectin and Albendazole on Helminth Infections in Southeastern Liberia. Am J Trop Med Hyg 2021; 106:700-709. [PMID: 34814104 PMCID: PMC8832944 DOI: 10.4269/ajtmh.21-0768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 09/20/2021] [Indexed: 12/04/2022] Open
Abstract
We compared the impact of three rounds of annual and five rounds of semiannual mass drug administration (MDA) with albendazole plus ivermectin on helminthic infections in Liberia. Repeated annual cross-sectional community surveys were conducted between 2013 and 2019 in individuals of 5 years and older. Primary outcome was the change of infection prevalence estimates from baseline to month 36 (12 months after the last treatment). After three rounds of annual MDA, Wuchereria bancrofti circulating filarial antigen (CFA) and microfilaria (Mf) prevalence estimates decreased from 19.7% to 4.3% and from 8.6% to 0%, respectively; after semiannual MDA, CFA and Mf prevalences decreased from 37.8% to 16.8% and 17.9% to 1%, respectively. Mixed effects logistic regression models indicated that the odds of having Mf decreased by 97% (P < 0.001) at month 36 (similar odds for annual and semiannual MDA zones). A parallel analysis showed that the odds of CFA were reduced by 83% and 69% at 36 months in the annual and semiannual treatment zones, respectively (P < 0.001). Onchocerca volvulus Mf prevalence decreased slightly after multiple MDA rounds in both treatment zones. Reductions in hookworm and Trichuris trichiura prevalences and intensities were slightly greater in the annual treatment zone. Ascaris lumbricoides prevalence rates were relatively unchanged, although infection intensities decreased sharply throughout. Results show that annual and semiannual MDA were equally effective for reducing LF and soil-transmitted helminth infection parameters over a 3-year period, and reductions recorded at month 36 were sustained by routine annual MDA through month 72.
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Affiliation(s)
- Obiora A Eneanya
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Lincoln Gankpala
- Division of Public Health and Medical Research, National Public Health Institute of Liberia, Charlesville, Republic of Liberia
| | - Charles W Goss
- Division of Biostatistics, Washington University School of Medicine, St. Louis, Missouri
| | - Fatorma K Bolay
- Division of Public Health and Medical Research, National Public Health Institute of Liberia, Charlesville, Republic of Liberia
| | - Gary J Weil
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Peter U Fischer
- Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
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Oguoma VM, Anyasodor AE, Adeleye AO, Eneanya OA, Mbanefo EC. Multilevel modelling of the risk of malaria among children aged under five years in Nigeria. Trans R Soc Trop Med Hyg 2021; 115:482-494. [PMID: 32945885 DOI: 10.1093/trstmh/traa092] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 08/11/2020] [Accepted: 08/26/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Malaria is still a major cause of morbidity and mortality among children aged <5 y (U5s). This study assessed individual, household and community risk factors for malaria in Nigerian U5s. METHODS Data from the Nigerian Malaria Health Indicator Survey 2015 were pooled for analyses. This comprised a national survey of 329 clusters. Children aged 6-59 mo who were tested for malaria using microscopy were retained. Multilevel logit model accounting for sampling design was used to assess individual, household and community factors associated with malaria parasitaemia. RESULTS A total of 5742 children were assessed for malaria parasitaemia with an overall prevalence of 27% (95% CI 26 to 28%). Plasmodium falciparum constituted 98% of the Plasmodium species. There was no significant difference in parasitaemia between older children and those aged ≤12 mo. In adjusted analyses, rural living, northwest region, a household size of >7, dependence on river and rainwater as primary water source were associated with higher odds of parasitaemia, while higher wealth index, all U5s who slept under a bed net and dependence on packaged water were associated with lower odds of parasitaemia. CONCLUSION Despite sustained investment in malaria control and prevention, a quarter of the overall study population of U5s have malaria. Across the six geopolitical zones, the highest burden was in children living in the poorest rural households.
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Affiliation(s)
- Victor M Oguoma
- Health Research Institute, University of Canberra, Canberra, ACT, Australia.,Child Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia
| | | | - Adeniyi O Adeleye
- School of Nursing, Midwifery and Social Sciences, Central Queensland University, Mackay, QLD, Australia
| | - Obiora A Eneanya
- Washington University School of Medicine, Department of Medicine, Infectious Diseases Division, St. Louis, MO, USA
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Eneanya OA, Fronterre C, Anagbogu I, Okoronkwo C, Garske T, Cano J, Donnelly CA. Mapping the baseline prevalence of lymphatic filariasis across Nigeria. Parasit Vectors 2019; 12:440. [PMID: 31522689 PMCID: PMC6745770 DOI: 10.1186/s13071-019-3682-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 08/22/2019] [Indexed: 11/30/2022] Open
Abstract
Introduction The baseline endemicity profile of lymphatic filariasis (LF) is a key benchmark for planning control programmes, monitoring their impact on transmission and assessing the feasibility of achieving elimination. Presented in this work is the modelled serological and parasitological prevalence of LF prior to the scale-up of mass drug administration (MDA) in Nigeria using a machine learning based approach. Methods LF prevalence data generated by the Nigeria Lymphatic Filariasis Control Programme during country-wide mapping surveys conducted between 2000 and 2013 were used to build the models. The dataset comprised of 1103 community-level surveys based on the detection of filarial antigenemia using rapid immunochromatographic card tests (ICT) and 184 prevalence surveys testing for the presence of microfilaria (Mf) in blood. Using a suite of climate and environmental continuous gridded variables and compiled site-level prevalence data, a quantile regression forest (QRF) model was fitted for both antigenemia and microfilaraemia LF prevalence. Model predictions were projected across a continuous 5 × 5 km gridded map of Nigeria. The number of individuals potentially infected by LF prior to MDA interventions was subsequently estimated. Results Maps presented predict a heterogeneous distribution of LF antigenemia and microfilaraemia in Nigeria. The North-Central, North-West, and South-East regions displayed the highest predicted LF seroprevalence, whereas predicted Mf prevalence was highest in the southern regions. Overall, 8.7 million and 3.3 million infections were predicted for ICT and Mf, respectively. Conclusions QRF is a machine learning-based algorithm capable of handling high-dimensional data and fitting complex relationships between response and predictor variables. Our models provide a benchmark through which the progress of ongoing LF control efforts can be monitored.
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Affiliation(s)
- Obiora A Eneanya
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK.
| | - Claudio Fronterre
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | | | | | - Tini Garske
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Jorge Cano
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Christl A Donnelly
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK.,Department of Statistics, University of Oxford, Oxford, UK
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Eneanya OA, Garske T, Donnelly CA. The social, physical and economic impact of lymphedema and hydrocele: a matched cross-sectional study in rural Nigeria. BMC Infect Dis 2019; 19:332. [PMID: 31014256 PMCID: PMC6480436 DOI: 10.1186/s12879-019-3959-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Accepted: 04/08/2019] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Lymphatic filariasis (LF) is a mosquito-borne parasitic disease and a major cause of disability worldwide. To effectively plan morbidity management programmes, it is important to estimate disease burden and evaluate the needs of patients. This study aimed to estimate patient numbers and characterise the physical, social and economic impact of LF in in rural Nigeria. METHODS This is a matched cross-sectional study which identified lymphedema and hydrocele patients with the help of district health officers and community-directed distributors of mass drug administration programmes. A total of 52 cases were identified and matched to 52 apparently disease-free controls, selected from the same communities and matched by age and sex. Questionnaires and narrative interviews were used to characterise the physical, social and economic impact of lymphedema and hydrocele. RESULTS Forty-eight cases with various stages of lower limb lymphedema, and 4 with hydrocele were identified. 40% of all cases reported feeling stigma and were 36 times (95% CI: 5.18-1564.69) more likely to avoid forms of social participation. Although most cases engaged in some form of income-generating activity, these were low paid employment, and on average cases spent significantly less time than controls working. The economic effects of lower income were exacerbated by increased healthcare spending, as cases were 86 times (95% CI: 17.48-874.90) more likely to spend over US $125 on their last healthcare payment. CONCLUSION This study highlights the importance of patient-search as a means of estimating the burden of LF morbidity in rural settings. Findings from this work also confirm that LF causes considerable psychosocial and economic suffering, all of which adversely affect the mental health of patients. It is therefore important to incorporate mental health care as a major component of morbidity management programmes.
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Affiliation(s)
- Obiora A. Eneanya
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, Faculty of Medicine, Norfolk Place, London, W2 1PG UK
| | - Tini Garske
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, Faculty of Medicine, Norfolk Place, London, W2 1PG UK
| | - Christl A. Donnelly
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, Faculty of Medicine, Norfolk Place, London, W2 1PG UK
- Department of Statistics, University of Oxford, Oxford, UK
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Eneanya OA, Cano J, Dorigatti I, Anagbogu I, Okoronkwo C, Garske T, Donnelly CA. Environmental suitability for lymphatic filariasis in Nigeria. Parasit Vectors 2018; 11:513. [PMID: 30223860 PMCID: PMC6142334 DOI: 10.1186/s13071-018-3097-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 09/04/2018] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Lymphatic filariasis (LF) is a mosquito-borne parasitic disease and a major cause of disability worldwide. It is one of the neglected tropical diseases identified by the World Health Organization for elimination as a public health problem by 2020. Maps displaying disease distribution are helpful tools to identify high-risk areas and target scarce control resources. METHODS We used pre-intervention site-level occurrence data from 1192 survey sites collected during extensive mapping surveys by the Nigeria Ministry of Health. Using an ensemble of machine learning modelling algorithms (generalised boosted models and random forest), we mapped the ecological niche of LF at a spatial resolution of 1 km2. By overlaying gridded estimates of population density, we estimated the human population living in LF risk areas on a 100 × 100 m scale. RESULTS Our maps demonstrate that there is a heterogeneous distribution of LF risk areas across Nigeria, with large portions of northern Nigeria having more environmentally suitable conditions for the occurrence of LF. Here we estimated that approximately 110 million individuals live in areas at risk of LF transmission. CONCLUSIONS Machine learning and ensemble modelling are powerful tools to map disease risk and are known to yield more accurate predictive models with less uncertainty than single models. The resulting map provides a geographical framework to target control efforts and assess its potential impacts.
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Affiliation(s)
- Obiora A. Eneanya
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Jorge Cano
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Ilaria Dorigatti
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | | | | | - Tini Garske
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Christl A. Donnelly
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, UK
- Department of Statistics, University of Oxford, Oxford, UK
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