Mortality and morbidity rates for infectious diseases vary greatly by geographical location. World Health Organization (WHO) statistics provide striking documentation that deaths due to infectious diseases are much higher in poor countries than in the countries with the highest income levels. It is particularly striking that malaria and tuberculosis are significant causes of death in low-resource countries, whereas these diseases are rarely fatal in wealthy countries. Other infectious diseases that significantly cause death in low-resource countries are pneumonia, diarrhea, and HIV infection. The top ten causes of death in lower and middle-resource countries In lower and middle-resource countries also include lower respiratory infections, tuberculosis, and diarrheal diseases. 

1. Define infection and identify the differences between colonization and infection, giving specific examples of each.

2. How does infection start, and what is the usual course?

3. What factors influence the course of an infection? Give specific examples of different trajectories of infection.