Communicable Diseases

Question 1

What are communicable diseases?

Answer 1

Illness caused by specific infectious (biological) agent OR its toxic products -capable of direct or indirect transmission from man to man or animal to man or animal to animal or from the environment (air, water, food …)

Question 2

Define incidence.

Answer 2

Infectious disease: no. of new cases in given time period = % infected per year (cumulative incidence) OR no. per person time of observation (incidence density)

Question 3

Define prevalence.

Answer 3

-Infectious disease: no. of cases at a given time expressed - as % at a given time
-Prevalence is a product of incidence x duration of disease, and is of little interest if an infectious disease is of short duration - but may be of interest if an infectious disease is of long duration