epidemiology

Endemic

disease is constantly present in population

Epidemic

Unusually large number of cases

Pandemic

larger outbreak- global

Attack rate

the percent of people who become ill after exposure 

Basic reproductive number (R0)

the average number of secondary cases that develop from a single case

incidence

Number of new cases/time/population

Prevalence

total number of cases at any time for a specific period in a given population

Morbidity

Incidence of disease in a population

Mortality

death rate

Vertical transmission vs horizontal

Vertical transmission is pregnant woman to fetus or mother to infant. Horizontal transmission is person to person

Descriptive study

data from an outbreak is collected to identify risk factors for spread

Analytical study

analsyis of data to determine relative importance of identified risk factors

Experimental study

study with a placebo group to grasp the effect of various interventions