Healthy Pop- Veterinary Epidemiology

Block 2

What are the components of the epidemiologic triad?

Host

Agent

Environment

What is infectivity?

the ability to penetrate and reproduce in a host; does not imply disease

What is pathogenicity?

the ability to cause clinical disease

What is virulence?

ability to cause severe disease or death 

What is a natural host?

maintains the infection in the endemic state

What is the amplifier host?

supports rapid multiplication of the agent

What is the dead-end host?

does not normally transmit the agent

What is the environment contribution?

is where the infectious agent normally lives, grows, and multiplies (the reservoir)

What is needed for infection to occur?

portal of exit

portal of entry

What is horizontal transmission?

spread between contemporaries via touching, biting, scratching, contaminated droplets, urine/body fluids, or reproductive discharge

What is vertical transmission?

mother-to-offspring (transplacental or transmammary)

What is direct transmission?

spread through direct contact with an infected animal, its tissues, ot fluids, or by droplet (aerosol) projection

What is indirect transmission?

spread through intermediary vehicle or vector

What is vehicle transmission?

inanimate object or fomite, ingestion from contaminated food or water or biological products

What is vector-born transmission?

transfer by an arthropod

What is a mechanical vector?

no multiplication or development of the agent

What is a biological vector?

allows multiplication or development of the agent

What are airborne (small particle) transmission?

travel large distances, remain suspended for extended periods

What is the epidemiologic triad for Bovine Spongiform Encephalopathy (BSE)?

Agent/Reservoir: prion

Transmission: food-borne disease by feeding ruminants protein supplements from other ruminant tissue

Intervention: ban feeding ruminant-source protein feeds to cattle

What is the epidemiologic triad for Rift Valley Fever (RVF)?

Agent/reservoir: aedes mosquito

Amplifying host: ruminants

Transmission: zoonotic transmission to humans occurs through direct contact with the blood or organs of infected animals

What does endemic mean?

disease occurs at an expected frequency

What does epidemic mean?

disease occurs at a greater than expected frequency

What does sporadic mean?

disease occurs occasionally as a single case or in small clusters