Probability Mass Function( P.M.

Definition of basic terms: Communicable disease: An illness due to specific infectious agent or its toxic products which develops through transmission of that agent or its toxic products from a reservoir to a susceptible host either directly or indirectly. Contagious disease - capable of spreading from one person to another Incubation period: The interval between exposure and first clinical manifestation. The time between exposure and first case is the minimum incubation period, The time between exposure and the last case, maximum incubation period.

Learning Objectives for the Lecture:
At the end of the lecture the student is going to be able to:
1. Define communicable and non-communicable diseases.
2. Describe the chain of infection.
3. Describe the links in the chain of infection.
Communicable Diseases
Communicable Diseases: They are diseases that spread by direct contact from infected person to a susceptible host.
Chain of infection: Series of events or conditions that lead to the development of communicable diseases.