Measles and Rubella Outbreaks in Ethiopia from 2008-2015: The Relative Importance of Different Factors Illuminated by Machine Learning

Abstract

Alleviating human suffering by manipulating live or attenuated strains of devastating diseases has proven to be one of humanity’s greatest achievements. Through immunization an estimated 2 to 3 millions deaths are averted every year. However, as far we’ve come, the gains made at the global and national coverage levels conceal varying levels at different spatial scales, such as at the regional and district levels. This thesis measures the relative influence of various demographics and spatial characteristics on measles and rubella cases in Ethiopia from 2009-March 2015. The covariance analysis makes use of two machine learning algorithms-- specifically gradient boosting, random forest-- and a logistic regression model to explore the importance of observational variables. Specifically, the analysis looks at demographic and geographical factors (e.g. remoteness, region, district, age, sex, and season, amongst others). The objective of these methods is to understand the relationship between different factors as predictors for the results of laboratory and clinically confirmed cases of measles and rubella. In addition, a third analysis was undertaken to measure the relative risk for measles in Ethiopia to identify the regions with an elevated risk ratio amongst Ethiopia’s 9 regions and 2 administrative cities. In the analysis, the most powerful relationship was observed from the geographical characteristics of measles and rubella cases. The analysis concludes that age clustering and urbanization rate are also correlated with both measles and rubella cases. The relative risk analysis empirically reveals that urbanized regions experience the highest incidence rating and the highest elevated risk ratio. These results serve as no surprise given the nature of the pathogens, which are directly transmitted from person-to-person. So too these viruses regularly cluster where susceptible hosts remain. These results underscore the need for countries to strengthening routine immunization campaigns because sustained high levels of vaccination are still the only protection for devastating measles and rubella outbreaks.