Suppose a veterinarian investigates a black disease that runs a clinical course ending in either recovery or death, in a flock of sheep. on 1 July 2001 the flock is investigated when the disease is already present. The flock is then observed for the following year, during which period there are no additions and all animals are followed up
Total flock size on 1 July 2001: 600
Total number clinically ill on 1 July 2001: 20
Total number developing clinical disease between 1 July 2001 and 1 July 2002: 80
Total number dying from the disease from 1 July 2001 to 1 July 2002: 30
:Calculate the following epidemiological parameters
Prevalence
Cumulative incidence
Population mortality rate
Case fatality