42.2  Types of epidemics

Epidemics are classified into different types according to the source of infection and modes of transmission.

  • From Study Session 1 of this Module, briefly describe the two main modes of transmission of communicable diseases.

  • They are: (1) direct modes of transmission, such as from mother to child, or from faecally contaminated hands into the mouth; and (2) indirect modes of transmission, such as through vectors, contaminated air, water, food or objects such as cooking bowls and utensils.

Based on criteria such as this, epidemics are classified into three types:

  • common source outbreaks
  • propagated or progressive epidemics
  • mixed epidemics.

We will look at each of them in turn.

42.1  What is an outbreak and an epidemic?

42.2.1  Common source outbreaks