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Barichello T, Rocha Catalão CH, Rohlwink UK, van der Kuip M, Zaharie D, Solomons RS, van Toorn R, Tutu van Furth M, Hasbun R, Iovino F, Namale VS. Bacterial meningitis in Africa. Front Neurol 2023; 14:822575. [PMID: 36864913 PMCID: PMC9972001 DOI: 10.3389/fneur.2023.822575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 01/18/2023] [Indexed: 02/16/2023] Open
Abstract
Bacterial meningitis differs globally, and the incidence and case fatality rates vary by region, country, pathogen, and age group; being a life-threatening disease with a high case fatality rate and long-term complications in low-income countries. Africa has the most significant prevalence of bacterial meningitis illness, and the outbreaks typically vary with the season and the geographic location, with a high incidence in the meningitis belt of the sub-Saharan area from Senegal to Ethiopia. Streptococcus pneumoniae (pneumococcus) and Neisseria meningitidis (meningococcus) are the main etiological agents of bacterial meningitis in adults and children above the age of one. Streptococcus agalactiae (group B Streptococcus), Escherichia coli, and Staphylococcus aureus are neonatal meningitis's most common causal agents. Despite efforts to vaccinate against the most common causes of bacterial neuro-infections, bacterial meningitis remains a significant cause of mortality and morbidity in Africa, with children below 5 years bearing the heaviest disease burden. The factors attributed to this continued high disease burden include poor infrastructure, continued war, instability, and difficulty in diagnosis of bacterial neuro-infections leading to delay in treatment and hence high morbidity. Despite having the highest disease burden, there is a paucity of African data on bacterial meningitis. In this article, we discuss the common etiologies of bacterial neuroinfectious diseases, diagnosis and the interplay between microorganisms and the immune system, and the value of neuroimmune changes in diagnostics and therapeutics.
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Affiliation(s)
- Tatiana Barichello
- Graduate Program in Health Sciences, University of Southern Santa Catarina (UNESC), Criciúma, SC, Brazil
- Faillace Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
| | - Carlos Henrique Rocha Catalão
- Faillace Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, United States
- Department of Neuroscience and Behavioral Science, Ribeirao Preto Medical School, University of São Paulo (USP), Ribeirao Preto, SP, Brazil
| | - Ursula K. Rohlwink
- Pediatric Neurosurgery Unit, Red Cross War Memorial Children's Hospital, Cape Town, South Africa
- Division of Neurosurgery, University of Cape Town, Cape Town, South Africa
- Neuroscience Institute, University of Cape Town, Cape Town, South Africa
| | - Martijn van der Kuip
- Department of Pediatric Infectious Diseases and Immunology, Amsterdam Infection and Immunity Institute, Amsterdam University Medical Centers, Vrije Universiteit, Amsterdam, Netherlands
| | - Dan Zaharie
- Department of Anatomical Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
- National Health Laboratory Services, Tygerberg Hospital, Cape Town, South Africa
| | - Regan S. Solomons
- Department of Pediatric and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Ronald van Toorn
- Department of Pediatric and Child Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Marceline Tutu van Furth
- Department of Pediatric Infectious Diseases and Immunology, Amsterdam Infection and Immunity Institute, Amsterdam University Medical Centers, Vrije Universiteit, Amsterdam, Netherlands
| | - Rodrigo Hasbun
- Division of Infectious Diseases, Department of Internal Medicine, UT Health, McGovern Medical School, Houston, TX, United States
| | - Federico Iovino
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Vivian Ssonko Namale
- Columbia University Irving Medical Center and New York Presbyterian Hospital, New York, NY, United States
- Department of Paediatrics and Child Health, Makerere University College of Health Sciences, Kampala, Uganda
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Bonell A, Contamin L, Thai PQ, Thuy HTT, van Doorn HR, White R, Nadjm B, Choisy M. Does sunlight drive seasonality of TB in Vietnam? A retrospective environmental ecological study of tuberculosis seasonality in Vietnam from 2010 to 2015. BMC Infect Dis 2020; 20:184. [PMID: 32111195 PMCID: PMC7048025 DOI: 10.1186/s12879-020-4908-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 02/19/2020] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Tuberculosis (TB) is a major global health burden, with an estimated quarter of the world's population being infected. The World Health Organization (WHO) launched the "End TB Strategy" in 2014 emphasising knowing the epidemic. WHO ranks Vietnam 12th in the world of high burden countries. TB spatial and temporal patterns have been observed globally with evidence of Vitamin D playing a role in seasonality. We explored the presence of temporal and spatial clustering of TB in Vietnam and their determinants to aid public health measures. METHODS Data were collected by the National TB program of Vietnam from 2010 to 2015 and linked to the following datasets: socio-demographic characteristics; climatic variables; influenza-like-illness (ILI) incidence; geospatial data. The TB dataset was aggregated by province and quarter. Descriptive time series analyses using LOESS regression were completed per province to determine seasonality and trend. Harmonic regression was used to determine the amplitude of seasonality by province. A mixed-effect linear model was used with province and year as random effects and all other variables as fixed effects. RESULTS There were 610,676 cases of TB notified between 2010 and 2015 in Vietnam. Heat maps of TB incidence per quarter per province showed substantial temporal and geospatial variation. Time series analysis demonstrated seasonality throughout the country, with peaks in spring/summer and troughs in autumn/winter. Incidence was consistently higher in the south, the three provinces with the highest incidence per 100,000 population were Tay Ninh, An Giang and Ho Chi Minh City. However, relative seasonal amplitude was more pronounced in the north. Mixed-effect linear model confirmed that TB incidence was associated with time and latitude. Of the demographic, socio-economic and health related variables, population density, percentage of those under 15 years of age, and HIV infection prevalence per province were associated with TB incidence. Of the climate variables, absolute humidity, average temperature and sunlight were associated with TB incidence. CONCLUSION Preventative public health measures should be focused in the south of Viet Nam where incidence is highest. Vitamin D is unlikely to be a strong driver of seasonality but supplementation may play a role in a package of interventions.
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Affiliation(s)
- Ana Bonell
- London School of Hygiene and Tropical Medicine, WC1E 7HT, London, UK.
- Oxford University Clinical Research Unit - Hanoi, National Hospital of Tropical Diseases, 78 Giai Phong, Hanoi, Vietnam.
| | - Lucie Contamin
- Oxford University Clinical Research Unit - Hanoi, National Hospital of Tropical Diseases, 78 Giai Phong, Hanoi, Vietnam
- Institute of Research for Development, 34394, Montpellier, France
| | - Pham Quang Thai
- National Institute of Hygiene and Epidemiology, 1 Yec Xanh, Pham Dinh Ho, Hai Ba Trung, Hanoi, 100000, Vietnam
| | | | - H Rogier van Doorn
- Oxford University Clinical Research Unit - Hanoi, National Hospital of Tropical Diseases, 78 Giai Phong, Hanoi, Vietnam
| | - Richard White
- TB Modelling Group, Department of Infectious Diseases Epidemiology, London School of Hygiene and Tropical Medicine, WC1E 7HT, London, UK
| | - Behzad Nadjm
- London School of Hygiene and Tropical Medicine, WC1E 7HT, London, UK
- Oxford University Clinical Research Unit - Hanoi, National Hospital of Tropical Diseases, 78 Giai Phong, Hanoi, Vietnam
| | - Marc Choisy
- Oxford University Clinical Research Unit - Hanoi, National Hospital of Tropical Diseases, 78 Giai Phong, Hanoi, Vietnam
- Institute of Research for Development, 34394, Montpellier, France
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Drivers of Seasonal Variation in Tuberculosis Incidence: Insights from a Systematic Review and Mathematical Model. Epidemiology 2019; 29:857-866. [PMID: 29870427 DOI: 10.1097/ede.0000000000000877] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Seasonality in tuberculosis incidence has been widely observed across countries and populations; however, its drivers are poorly understood. We conducted a systematic review of studies reporting seasonal patterns in tuberculosis to identify demographic and ecologic factors associated with timing and magnitude of seasonal variation. METHODS We identified studies reporting seasonal variation in tuberculosis incidence through PubMed and EMBASE and extracted incidence data and population metadata. We described key factors relating to seasonality and, when data permitted, quantified seasonal variation and its association with metadata. We developed a dynamic tuberculosis natural history and transmission model incorporating seasonal differences in disease progression and/or transmission rates to examine magnitude of variation required to produce observed seasonality in incidence. RESULTS Fifty-seven studies met inclusion criteria. In the majority of studies (n=49), tuberculosis incidence peaked in spring or summer and reached a trough in late fall or winter. A standardized seasonal amplitude was calculated for 34 of the studies, resulting in a mean of 17.1% (range: 2.7-85.5%) after weighting by sample size. Across multiple studies, stronger seasonality was associated with younger patients, extrapulmonary disease, and latitudes farther from the Equator. The mathematical model was generally able to reproduce observed levels of seasonal case variation; however, substantial variation in transmission or disease progression risk was required to replicate several extreme values. CONCLUSIONS We observed seasonal variation in tuberculosis, with consistent peaks occurring in spring, across countries with varying tuberculosis burden. Future research is needed to explore and quantify potential gains from strategically conducting mass screening interventions in the spring.
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Fernandes FMDC, Martins EDS, Pedrosa DMAS, Evangelista MDSN. Relationship between climatic factors and air quality with tuberculosis in the Federal District, Brazil, 2003–2012. Braz J Infect Dis 2017; 21:369-375. [PMID: 28545939 PMCID: PMC9428008 DOI: 10.1016/j.bjid.2017.03.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2016] [Revised: 01/24/2017] [Accepted: 03/27/2017] [Indexed: 12/12/2022] Open
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Boere TM, Visser DH, van Furth AM, Lips P, Cobelens FGJ. Solar ultraviolet B exposure and global variation in tuberculosis incidence: an ecological analysis. Eur Respir J 2017; 49:49/6/1601979. [PMID: 28619953 DOI: 10.1183/13993003.01979-2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Accepted: 03/11/2017] [Indexed: 11/05/2022]
Abstract
Epidemiological evidence supports vitamin D deficiency as a risk factor for tuberculosis. Differences in solar ultraviolet B (UV-B) exposure, the major source of vitamin D, might therefore partially explain global variation in tuberculosis incidence.In a global country-based ecological study, we explored the correlation between vitamin D-proxies, such as solar UV-B exposure, and other relevant variables with tuberculosis incidence, averaged over the period 2004-2013.Across 154 countries, annual solar UV-B exposure was associated with tuberculosis incidence. Tuberculosis incidence in countries in the highest quartile of UV-B exposure was 78% (95% CI 57-88%, p<0.001) lower than that in countries in the lowest quartile, taking into account other vitamin D-proxies and covariates. Of the explained global variation in tuberculosis incidence, 6.3% could be attributed to variations in annual UV-B exposure. Exposure to UV-B had a similar, but weaker association with tuberculosis notification rates in the multilevel analysis with sub-national level data for large countries (highest versus lowest quartile 29% lower incidence; p=0.057).The potential preventive applications of vitamin D supplementation in high-risk groups for tuberculosis merits further investigation.
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Affiliation(s)
- Tjarda M Boere
- Amsterdam Institute for Global Health and Development and Dept of Global Health, Academic Medical Centre, Amsterdam, The Netherlands.,Faculty of Earth and Life Sciences, Dept of Health Sciences, Section of Infectious Diseases, Vrije Universiteit, Amsterdam, The Netherlands
| | - Douwe H Visser
- Dept of Paediatrics, OLVG West Medical Centre, Amsterdam, The Netherlands
| | - A Marceline van Furth
- Dept of Paediatric Infectious Diseases and Immunology, VU Medical Centre, Amsterdam, The Netherlands
| | - Paul Lips
- Dept of Internal Medicine, Endocrine section, VU Medical Centre, Amsterdam, The Netherlands
| | - Frank G J Cobelens
- Amsterdam Institute for Global Health and Development and Dept of Global Health, Academic Medical Centre, Amsterdam, The Netherlands .,KNCV Tuberculosis Foundation, The Hague, The Netherlands
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You S, Tong YW, Neoh KG, Dai Y, Wang CH. On the association between outdoor PM 2.5 concentration and the seasonality of tuberculosis for Beijing and Hong Kong. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2016; 218:1170-1179. [PMID: 27595179 DOI: 10.1016/j.envpol.2016.08.071] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 08/25/2016] [Accepted: 08/25/2016] [Indexed: 05/16/2023]
Abstract
Tuberculosis (TB) is still a serious public health problem in various countries. One of the long-elusive but critical questions about TB is what the risk factors are and how they contribute for its seasonality. An ecologic study was conducted to examine the association between the variation of outdoor PM2.5 concentration and the TB seasonality based on the monthly TB notification and PM2.5 concentration data of Hong Kong and Beijing. Both descriptive analysis and Poisson regression analysis suggested that the outdoor PM2.5 concentration could be a potential risk factor for the seasonality of TB disease. The significant relationship between the number of TB cases and PM2.5 concentration was not changed when regression models were adjusted by sunshine duration, a potential confounder. The regression analysis showed that a 10 μg/m3 increase in PM2.5 concentrations during winter is significantly associated with a 3% (i.e. 18 and 14 cases for Beijing and Hong Kong, respectively) increase in the number of TB cases notified during the coming spring or summer for both Beijing and Hong Kong. Three potential mechanisms were proposed to explain the significant relationship: (1) increased PM2.5 exposure increases host's susceptibility to TB disease by impairing or modifying the immunology of the human respiratory system; (2) increased indoor activities during high outdoor PM2.5 episodes leads to an increase in human contact and thus the risk of TB transmission; (3) the seasonal change of PM2.5 concentration is correlated with the variation of other potential risk factors of TB seasonality. Preliminary evidence from the analysis of this work favors the first mechanism about the PM2.5 exposure-induced immunity impairment. This work adds new horizons to the explanation of the TB seasonality and improves our understanding of the potential mechanisms affecting TB incidence, which benefits the prevention and control of TB disease.
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Affiliation(s)
- Siming You
- NUS Environmental Research Institute, National University of Singapore, 1 Create Way, Create Tower, #15-02, 138602, Singapore
| | - Yen Wah Tong
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585, Singapore
| | - Koon Gee Neoh
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585, Singapore
| | - Yanjun Dai
- School of Mechanical Engineering, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240, China
| | - Chi-Hwa Wang
- Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, 117585, Singapore.
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Vitamin D Status and Its Consequences for Health in South Africa. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2016; 13:ijerph13101019. [PMID: 27763570 PMCID: PMC5086758 DOI: 10.3390/ijerph13101019] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Revised: 10/10/2016] [Accepted: 10/10/2016] [Indexed: 12/14/2022]
Abstract
In this review, reports were retrieved in which vitamin D status, as assessed by serum 25-hydroxyvitamin D [25(OH)D] levels, was measured in South African population groups with varied skin colours and ethnicities. Healthy children and adults were generally vitamin D-sufficient [25(OH)D level >50 nmol/L] but the majority of those aged above 65 years were deficient. A major role for exposure to solar ultraviolet radiation (UVR) in determining 25(OH)D levels was apparent, with the dietary contribution being minor. Limited data exist regarding the impact of recent changes in lifestyles on vitamin D status, such as urbanisation. With regard to disease susceptibility, 11 of 22 relevant publications indicated association between low 25(OH)D levels and disease, with deficiency most notably found in individuals with tuberculosis and HIV-1. Information on the relationship between vitamin D receptor variants and ethnicity, disease or treatment response in the South African population groups demonstrated complex interactions between genetics, epigenetics and the environment. Whether vitamin D plays an important role in protection against the range of diseases that currently constitute a large burden on the health services in South Africa requires further investigation. Only then can accurate advice be given about personal sun exposure or dietary vitamin D supplementation.
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Rizvi I, Garg RK, Jain A, Malhotra HS, Singh AK, Prakash S, Kumar N, Garg R, Verma R, Mahdi AA, Sharma PK. Vitamin D status, vitamin D receptor and toll like receptor-2 polymorphisms in tuberculous meningitis: a case–control study. Infection 2016; 44:633-40. [DOI: 10.1007/s15010-016-0907-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 05/07/2016] [Indexed: 12/19/2022]
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Facchini L, Venturini E, Galli L, Martino MD, Chiappini E. Vitamin D and tuberculosis: a review on a hot topic. J Chemother 2015; 27:128-38. [DOI: 10.1179/1973947815y.0000000043] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Visser DH, Solomons RS, Ronacher K, van Well GT, Heymans MW, Walzl G, Chegou NN, Schoeman JF, van Furth AM. Host immune response to tuberculous meningitis. Clin Infect Dis 2014; 60:177-87. [PMID: 25301213 DOI: 10.1093/cid/ciu781] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Tuberculous meningitis (TBM) is a severe complication of tuberculosis predominantly affecting young children. Early treatment is vital to prevent morbidity and mortality, emphasizing the importance of early diagnosis. The lack of sensitive methods for early diagnosis is the most common cause of delay. Attempts have been made to develop simplified tests for tuberculosis, but their diagnostic power remains poor. The clinical picture of TBM is mainly driven by the host's immune response to Mycobacterium tuberculosis; therefore, identification of disease-specific biomarkers may have diagnostic and therapeutic value and improve our understanding of its pathogenesis. METHODS We investigated disease-specific biomarkers of childhood TBM in a cohort of children aged 3 months-13 years with symptoms and signs suggestive of meningitis. Cerebrospinal fluid (CSF) and serum from 56 patients with and 55 patients without TBM were assessed for 28 soluble mediators. RESULTS Unsupervised hierarchical clustering analysis revealed a disease-specific pattern of biomarkers for TBM relative to other types of meningitis. A biomarker-based diagnostic prediction model for childhood TBM based on CSF concentrations of interleukin 13 (cutoff value, 37.26 pg/mL), vascular endothelial growth factor (cutoff value, 42.92 pg/mL), and cathelicidin LL-37 (cutoff value, 3221.01 pg/mL) is presented with a sensitivity of 0.52 and a specificity of 0.95. CONCLUSIONS These data highlight the potential of biosignatures in the host's CSF for diagnostic applications and for improving our understanding of the pathogenesis of TBM to discover strategies to prevent immunopathological sequelae.
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Affiliation(s)
- Douwe H Visser
- Department of Paediatric Infectious Diseases and Immunology, VU University Medical Center, Amsterdam, The Netherlands
| | - Regan S Solomons
- Department of Paediatrics and Child Health, Faculty of Medicine and Health Sciences
| | - Katharina Ronacher
- Division of Molecular Biology and Human Genetics, Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, MRC Unit for Molecular and Cellular Biology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Gijs T van Well
- Department of Paediatric Infectious Diseases and Immunology, VU University Medical Center, Amsterdam, The Netherlands Department of Paediatrics, Maastricht University Medical Center (MUMC+), Maastricht
| | - Martijn W Heymans
- Department of Epidemiology and Biostatistics, The EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands
| | - Gerhard Walzl
- Division of Molecular Biology and Human Genetics, Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, MRC Unit for Molecular and Cellular Biology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Novel N Chegou
- Division of Molecular Biology and Human Genetics, Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, MRC Unit for Molecular and Cellular Biology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Johan F Schoeman
- Department of Paediatrics and Child Health, Faculty of Medicine and Health Sciences
| | - Anne M van Furth
- Department of Paediatric Infectious Diseases and Immunology, VU University Medical Center, Amsterdam, The Netherlands
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Abstract
Tuberculous meningitis is especially common in young children and people with untreated HIV infection, and it kills or disables roughly half of everyone affected. Childhood disease can be prevented by vaccination and by giving prophylactic isoniazid to children exposed to infectious adults, although improvements in worldwide tuberculosis control would lead to more effective prevention. Diagnosis is difficult because clinical features are non-specific and laboratory tests are insensitive, and treatment delay is the strongest risk factor for death. Large doses of rifampicin and fluoroquinolones might improve outcome, and the beneficial effect of adjunctive corticosteroids on survival might be augmented by aspirin and could be predicted by screening for a polymorphism in LTA4H, which encodes an enzyme involved in eicosanoid synthesis. However, these advances are insufficient in the face of drug-resistant tuberculosis and HIV co-infection. Many questions remain about the best approaches to prevent, diagnose, and treat tuberculous meningitis, and there are still too few answers.
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El-Kebir M, van der Kuip M, van Furth AM, Kirschner DE. Computational modeling of tuberculous meningitis reveals an important role for tumor necrosis factor-α. J Theor Biol 2013; 328:43-53. [PMID: 23542051 DOI: 10.1016/j.jtbi.2013.03.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 03/12/2013] [Accepted: 03/12/2013] [Indexed: 12/30/2022]
Abstract
Tuberculosis is a global health issue with annually about 1.5 million deaths and 2 billion infected people worldwide. Extra-pulmonary tuberculosis comprises 13% of all cases of which tuberculous meningitis is the most severe. It has a high mortality and is often diagnosed once irreversible neurological damage has already occurred. Development of diagnostic and treatment strategies requires a thorough understanding of the pathogenesis of tuberculous meningitis. This disease is characterized by the formation of a cerebral granuloma, which is a collection of immune cells that attempt to immunologically restrain, and physically contain bacteria. The cytokine tumor necrosis factor-α is known for its important role in granuloma formation. Because traditional experimental animal studies exploring tuberculous meningitis are difficult and expensive, another approach is needed to begin to address this important and significant disease outcome. Here, we present an in silico model capturing the unique immunological environment of the brain that allows us to study the key mechanisms driving granuloma formation in time. Uncertainty and sensitivity analysis reveals a dose-dependent effect of tumor necrosis factor-α on bacterial load and immune cell numbers thereby influencing the onset of tuberculous meningitis. Insufficient levels result in bacterial overgrowth, whereas high levels lead to uncontrolled inflammation being detrimental to the host. These findings have important implications for the development of immuno-modulating treatment strategies for tuberculous meningitis.
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Affiliation(s)
- M El-Kebir
- Department of Pediatric Infectious diseases and Immunology, VU University Medical Center, Amsterdam, The Netherlands
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Koh GCKW, Hawthorne G, Turner AM, Kunst H, Dedicoat M. Tuberculosis incidence correlates with sunshine: an ecological 28-year time series study. PLoS One 2013; 8:e57752. [PMID: 23483924 PMCID: PMC3590299 DOI: 10.1371/journal.pone.0057752] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Accepted: 01/29/2013] [Indexed: 12/14/2022] Open
Abstract
Background Birmingham is the largest UK city after London, and central Birmingham has an annual tuberculosis incidence of 80 per 100,000. We examined seasonality and sunlight as drivers of tuberculosis incidence. Hours of sunshine are seasonal, sunshine exposure is necessary for the production of vitamin D by the body and vitamin D plays a role in the host response to tuberculosis. Methods We performed an ecological study that examined tuberculosis incidence in Birmingham from Dec 1981 to Nov 2009, using publicly-available data from statutory tuberculosis notifications, and related this to the seasons and hours of sunshine (UK Meteorological Office data) using unmeasured component models. Results There were 9,739 tuberculosis cases over the study period. There was strong evidence for seasonality, with notifications being 24.1% higher in summer than winter (p<0.001). Winter dips in sunshine correlated with peaks in tuberculosis incidence six months later (4.7% increase in incidence for each 100 hours decrease in sunshine, p<0.001). Discussion and Conclusion A potential mechanism for these associations includes decreased vitamin D levels with consequent impaired host defence arising from reduced sunshine exposure in winter. This is the longest time series of any published study and our use of statutory notifications means this data is essentially complete. We cannot, however, exclude the possibility that another factor closely correlated with the seasons, other than sunshine, is responsible. Furthermore, exposure to sunlight depends not only on total hours of sunshine but also on multiple individual factors. Our results should therefore be considered hypothesis-generating. Confirmation of a potential causal relationship between winter vitamin D deficiency and summer peaks in tuberculosis incidence would require a randomized-controlled trial of the effect of vitamin D supplementation on future tuberculosis incidence.
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Affiliation(s)
- Gavin C K W Koh
- Department of Infection and Tropical Medicine, Heartlands Hospital, Birmingham, United Kingdom.
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