Introduction to Infectious Diseases

Infectious diseases are the second leading cause of death worldwide, after heart disease, and are responsible for more deaths annually than cancer. Infectious diseases claim 16.2 percent of people who die each year. Children under the age of five are especially vulnerable, and infectious diseases account for a disproportionate number deaths in this group. Of the top ten causes of death reported by the World Health Organization in 2008, four were due to infectious diseases. However, low-income countries are more severely affected by infectious diseases, and in these countries, five of the top killers were due to infectious agents, with lower respiratory infections being the number one cause of death.