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Linkages Between Saharan Dust Proxies, Climate, and Meningitis in West Africa from 2012 to 2017
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Yarber, Aara L
Master of Science
Date of Defense:
June 03, 2020
Gregory S Jenkins, Thesis Advisor/Co-Advisor
Matthew Joseph Ferrari, Committee Member
Amy K. Huff, Committee Member
David Jonathan Stensrud, Program Head/Chair
The harmattan, a dry, northeasterly trade wind, transports large quantities of Saharan dust over the Sahelian region during the dry season (December-April). Limited studies have shown that bacterial meningitis outbreaks in Sahelian regions show hyper-endemic to endemic levels during high-dust months. I explore and compare the relationships between Saharan dust, temperature, relative humidity, wind speed, visibility, Aerosol Optical Depth (AOD), and meningitis incidence in Senegal, Burkina Faso, and Niger from 2012 to 2017. These countries were selected based on their differences in disease incidence. More specifically, I examine (i) the seasonality and intra-seasonal variability of dust, climate, and meningitis in each country and (ii) how the intensity, frequency, and duration of dust events impact the intensity of meningitis incidence. The results show that the dust onset occurs in December followed by the onset of meningitis during January in Burkina Faso and February in Senegal and Niger. I observe a second peak in dust in February followed by a peak in meningitis in March. Meningitis has the strongest correlation with AOD during the onset to the peak of meningitis season, but the correlation coefficients weaken for the entire meningitis season when the dust is lofted to higher altitudes. Outbreaks decline during the humid season when visibility and relative humidity increases. The meningitis season ends in Burkina Faso and Niger when the mean monthly relative humidity reaches 40%. Furthermore, I find that a high seasonal aerosol load, frequent intense dusty days, and long-lasting back to back dust events may favor high meningitis incidence. In addition to dust, air temperature and relative humidity from December to March may strongly influence the number of meningitis cases in each country.
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