epidemics learning objs

Communicable disease

Infectious disease that can be transmitted from one host to another

Noncommunicable disease

Disease not spread from host to host; usually from normal microbiota, environment, or

Epidemic

A sudden increase in the number of cases above what is normally expected in a population

Common source epidemic

Many people infected from the same source

Propagated epidemic

Spreads person-to-person over time; cases rise more slowly and last longer

Endemic

Disease constantly present at a stable level in a population

Sporadic

Disease occurs only occasionally and infrequently

Pandemic

A worldwide epidemic affecting multiple continents :

Incidence

The number of new cases of a disease in a population during a defined time period

Prevalence

The total number of existing cases (new + ongoing) in a population at a single point in time

Chain of infection

The steps required for a pathogen to spread from one host to another

Infectious agent

A microbe with virulence factors that allow infection and disease

Reservoir

Where the pathogen naturally lives and multiplies

Portal of exit

The route pathogens leave the reservoir

Transmission

How the pathogen travels to a new host

Portal of entry

Where the pathogen enters the next host

Susceptible host

One who cannot resist infection due to lack of immunity or weakened defenses

Breaking the chain

Remove reservoir, prevent transmission, treat infected individuals, and increase immunity

Smallpox eradication

Human was only reservoir; no latent stage; no antigenic variation; vaccine gave lifelong immunity; cases easily identified; surveillance + containment successful