Morbidity is any departure from physiological well-being. Sources of morbidity statistics are—reporting of disease, case registries, surveys, hospital records, MIS. Morbidity is described by incidence rate, prevalence rate. Attack rate and secondary are special types of incidence rate. Attack rate is used to describe the disease occurrence during the outbreak of an infectious disease. Secondary attack rate measures the spread of infections within a group after exposure to primary case. Morbidity statistics is used for planning and evaluation of health programs and services. It is used for disease control and disease surveillance.