A population with a low literacy rate is less likely to have access to health education, which would be used to develop preventative health practices. A population with a low literacy rate usually performs unskilled labor for low wages and therefore has less income and access to healthcare. A nation with a low literacy rate is also less likely to have a stable government with the economic resources to provide infrastructure, sanitation, and healthcare. Finally, a population with a low literacy rate is more likely to have a rapidly growing population. This contributes to the spread of disease because it is harder for the government to provide adequate healthcare services to exploding populations.
My theory involves the following three factors, a) the higher the literacy rates the more educated and higher income so more likely better fed and therefore less susceptible to disease, b) people who are literate can read about remedies ie they can investigate what can help them with their illnesses and c) a country which promotes literacy more than likely has social programs to help with such things as malnutrition for example which have a bearing on disease and also on improved medical treatments such as occurred in Cuba since the revolution.
