Modelling environmental factors correlated with podoconiosis: a geospatial study of non-filarial elephantiasis

International Journal of Health Geographics

Gail Davey³  Peter M Atkinson⁴  Melanie J Newport³  Peter Baxter²  Jennifer S Le Blond¹  Nicola A Wardrop⁴  Yordanos B Molla³ 

[1] Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK;Institute of Public Health, University of Cambridge, Cambridge CB2 2SR, UK;Brighton and Sussex Medical School, Falmer, Brighton BN1 9PS, UK;Geography and Environment, University of Southampton, Highfield Campus, Southampton SO17 1BJ, UK

关键词: Ethiopia;    Soil;    Epidemiology;    Spatial analysis;    Podoconiosis;   

Others  :  804410
DOI  :  10.1186/1476-072X-13-24

 received in 2014-04-07, accepted in 2014-06-10,  发布年份 2014

【 摘 要 】

Introduction

The precise trigger of podoconiosis — endemic non-filarial elephantiasis of the lower legs — is unknown. Epidemiological and ecological studies have linked the disease with barefoot exposure to red clay soils of volcanic origin. Histopathology investigations have demonstrated that silicon, aluminium, magnesium and iron are present in the lower limb lymph node macrophages of both patients and non-patients living barefoot on these clays. We studied the spatial variation (variations across an area) in podoconiosis prevalence and the associated environmental factors with a goal to better understanding the pathogenesis of podoconiosis.

Methods

Fieldwork was conducted from June 2011 to February 2013 in 12 kebeles (administrative units) in northern Ethiopia. Geo-located prevalence data and soil samples were collected and analysed along with secondary geological, topographic, meteorological and elevation data. Soil data were analysed for chemical composition, mineralogy and particle size, and were interpolated to provide spatially continuous information. Exploratory, spatial, univariate and multivariate regression analyses of podoconiosis prevalence were conducted in relation to primary (soil) and secondary (elevation, precipitation, and geology) covariates.

Results

Podoconiosis distribution showed spatial correlation with variation in elevation and precipitation. Exploratory analysis identified that phyllosilicate minerals, particularly clay (smectite and kaolinite) and mica groups, quartz (crystalline silica), iron oxide, and zirconium were associated with podoconiosis prevalence. The final multivariate model showed that the quantities of smectite (RR = 2.76, 95% CI: 1.35, 5.73; p = 0.007), quartz (RR = 1.16, 95% CI: 1.06, 1.26; p = 0.001) and mica (RR = 1.09, 95% CI: 1.05, 1.13; p < 0.001) in the soil had positive associations with podoconiosis prevalence.

Conclusions

More quantities of smectite, mica and quartz within the soil were associated with podoconiosis prevalence. Together with previous work indicating that these minerals may influence water absorption, potentiate infection and be toxic to human cells, the present findings suggest that these particles may play a role in the pathogenesis of podoconiosis and acute adenolymphangitis, a common cause of morbidity in podoconiosis patients.

【 授权许可】

   
2014 Molla et al.; licensee BioMed Central Ltd.

【 图 表 】

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【 参考文献 】

• [1]Price EW: Podoconiosis: non-filarial elephantiasis. Oxford: Oxford Medical Publications; 1990.
• [2]Price EW: The relationship between endemic elephantiasis of the lower legs and the local soils and climate. Trop Geogr Med 1974, 26:225-230.
• [3]Price EW: The association of endemic elephantiasis of the lower legs in East Africa with soil derived from volcanic rocks. Trans R Soc Trop Med Hyg 1976, 70:288-295.
• [4]Price EW, Bailey D: Environmental factors in the etiology of endemic elephantiasis of the lower legs in tropical Africa. Trop Geogr Med 1984, 36:1-5.
• [5]Price EW, McHardy WJ, Pooley FD: Endemic elephantiasis of the lower legs as a health hazard of barefooted agriculturalists in Cameroon, West Africa. Ann Occup Hyg 1981, 24:1-8.
• [6]Price EW, Henderson WJ: Endemic elephantiasis of the lower legs in the United Cameroon Republic. Trop Geogr Med 1981, 33:23-29.
• [7]Price EW, Henderson W: The elemental content of lymphatic tissues of barefooted people in Ethiopia, with reference to endemic elephantiasis of the lower legs. Trans R Soc Trop Med Hyg 1978, 72:132-136.
• [8]Frommel D, Ayranci B, Pfeifer HR, Sanchez A, Frommel A, Mengistu G: Podoconiosis in the Ethiopian Rift Valley. Role of beryllium and zirconium. Trop Geogr Med 1993, 45:165-167.
• [9]Harvey R, Powell JJ, Thompson RPH: A review of the geochemical factors linked to podoconiosis. Geol Soc Lond, Spec Publ 1996, 113:255-260.
• [10]Price EW: Endemic elephantiasis of the lower legs in Ethiopia an epidemiological survey. Ethiop Med J 1974, 12:77-90.
• [11]Price EW: The significance of particle size of soils as a risk factor in the etiology of podoconiosis. Trans R Soc Trop Med Hyg 1990, 84:885-886.
• [12]Odom IE: Smectite clay Minerals: properties and Uses. Philos Trans R Soc Lond A 1984, 311:391-409.
• [13]Carretero MI: Clay minerals and their beneficial effects upon human health. Appl Clay Sci 2002, 21:155-163.
• [14]Carretero MI, Pozo M: Clay and non-clay minerals in the pharmaceutical and cosmetic industries Part II. Active ingredients. Appl Clay Sci 2010, 47:171-181.
• [15]Saroha K, Singh S, Aggarwal A, Nanda S: Transdermal gels - an alternative vehicle for drug delivery. IJPCBS 2013, 3:495-503.
• [16]Tateo F, Ravaglioli A, Andreoli C, Bonina F, Coiro V, Degetto S, Giaretta A, Menconi Orsini A, Puglia C, Summa V: The in-vitro percutaneous migration of chemical elements from a thermal mud for healing use. Appl Clay Sci 2009, 44:83-94.
• [17]Addisu S, El-Metwally TH, Davey G, Worku Y, Titheradge MA: The role of transforming growth factor-beta1 and oxidative stress in podoconiosis pathogenesis. Br J Dermatol 2010, 162:998-1003.
• [18]Rodeheaver G, Pettry D, Turnbull V, Edgerton MT, Edlich RF: Identification of the wound infection-potentiating factors in soil. Am J Surg 1974, 128:8-14.
• [19]Dougherty SH, Fiegel VD, Nelson RD, Rodeheaver GT, Simmons RL: Effects of soil infection potentiating factors on neutrophils in vitro. Am J Surg 1985, 150:306-311.
• [20]Brennan FP, Moynihan E, Griffiths BS, Hillier S, Owen J, Pendlowski H, Avery LM: Clay mineral type effect on bacterial enteropathogen survival in soil. Sci Total Environ 2014, 468:302-305.
• [21]Otto CC, Haydel SE: Exchangeable Ions Are Responsible for the In Vitro Antibacterial Properties of Natural Clay Mixtures. PLoS One 2013, 8:e64068.
• [22]Williams LB, Metge DW, Eberl DD, Harvey RW, Turner AG, Prapaipong P, Poret-Peterson AT: What Makes a Natural Clay Antibacterial? Environ Sci Technol 2011, 45:3768-3773.
• [23]Ferguson JS, Yeshanehe WE, Matts PJ, Davey G, Mortimer PS, Fuller LC: Assessment of skin barrier function in podoconiosis: measurement of stratum corneum hydration and transepidermal water loss. Br J Dermatol 2013, 168:550-554.
• [24]Fuller LC: Podoconiosis: endemic nonfilarial elephantiasis. Curr Opin Infect Dis 2005, 18:119-122.
• [25]Molla YB, Tomczyk S, Amberbir T, Tamiru A, Davey G: Podoconiosis in East and West Gojam Zones, northern Ethiopia. PLoS Negl Trop Dis 2012, 6:e1744.
• [26]Cassel SL, Eisenbarth SC, Iyer SS, Sadler JJ, Colegio OR, Tephly LA, Carter AB, Rothman PB, Flavell RA, Sutterwala FS: The Nalp3 inflammasome is essential for the development of silicosis. Proc Natl Acad Sci U S A 2008, 105:9035-9040.
• [27]Lacasse Y, Martin S, Gagne D, Lakhal L: Dose–response meta-analysis of silica and lung cancer. Cancer Causes Control 2009, 20:925-933.
• [28]Steenland K, Ward E: Silica: a lung carcinogen. CA Cancer J Clin 2013, 68(1):63-69.
• [29]IARC: International Agency for Research on Cancer (IARC) Monographs on the Evaluation of Carcinogenic Risks to Humans. IARC Monogr 2012, 100C:355.
• [30]Fyfe NC, Price EW: The effects of silica on lymph nodes and vessels–a possible mechanism in the pathogenesis of non-filarial endemic elephantiasis. Trans R Soc Trop Med Hyg 1985, 79:645-651.
• [31]Couture P, Blaise C, Cluis D, Bastien C: Zirconium toxicity assessment using bacteria, algae and fish assays. Water Air Soil Pollut 1989, 47:87-100.
• [32]Emsley J: Nature’s Building Blocks. Oxford: Oxford University Press; 2001.
• [33]Cullander C, Jeske S, Imbert D, Grant PG, Bench G: A quantitative minimally invasive assay for the detection of metals in the stratum corneum. J Pharm Biomed Anal 2000, 22:265-279.
• [34]Lansdown AB: Metal ions affecting the skin and eyes. Met Ions Life Sci 2011, 8:187-246.
• [35]Benohanian A: Antiperspirants and deodorants. Clin Dermatol 2001, 19:398-405.
• [36]Knapik JJ, Reynolds K, Barson J: Influence of an antiperspirant on foot blister incidence during cross-country hiking. J Am Acad Dermatol 1998, 39:202-206.
• [37]Tekola Ayele F, Adeyemo A, Finan C, Hailu E, Sinnott P, Burlinson ND, Aseffa A, Rotimi CN, Newport MJ, Davey G: HLA class II locus and susceptibility to podoconiosis. N Engl J Med 2012, 366:1200-1208.
• [38]Molla YB, Le Blond J, Wardrop N, Baxter P, Atkinson P, Newport M, Davey G: Individual correlates of podoconiosis in areas of varying endemicity: a case–control study. PLoS Negl Trop Dis 2013, 7:e2554.
• [39]Molitor J, Jerrett M, Chang CC, Molitor NT, Gauderman J, Berhane K, McConnell R, Lurmann F, Wu J, Winer A, Thomas D: Assessing uncertainty in spatial exposure models for air pollution health effects assessment. Environ Health Perspect 2007, 115:1147-1153.
• [40]Burnett R, Ma R, Jerrett M, Goldberg MS, Cakmak S, Pope CA 3rd, Krewski D: The spatial association between community air pollution and mortality: a new method of analyzing correlated geographic cohort data. Environ Health Perspect 2001, 3:375-380.
• [41]Le Blond J, Cuadros J, Molla YB, Berhanu T, Umer M, Baxter P, Davey G: Weathering of the Ethiopian plateau flood basalt, NW Ethiopia: a new weathering index to characterise and compare soils. Chem Geol 2014. Submitted
• [42]Dubrule O: Two methods with different objectives: splines and kriging. J Int Assoc Math Geol 1983, 15(2):245-257.
• [43]Hengl T, Heuvelink GBM, Rossiter DG: About regression-kriging: from equations to case studies. Comput Geosci 2007, 33(10):1301-1315.