Epidemiological Models
This simple model shows disease results from the interaction of agent, host, and environment.
Epidemiological Triangle
Touching, kissing, or droplets are examples of this type of disease spread
Direct transmission
Immunity you are born with
natural immunity
Researchers examine how John’s diet, stress level, and neighborhood contribute to his risk of developing diabetes.
wheel model of causation
Transfer of an infection from person to person
horizontal transmission
Public health officials study how smoking, air pollution, and genetics interact to increase lung cancer risk in a population.
Web of causation
Pathogens can spread via contaminated objects, water, food, or vectors in this form of transmission.
Indirect transmission
Immunity acquired after getting an infection
Acquired immunity
A small town notices that residents in one neighborhood have higher rates of asthma. Investigators find that people are exposed to dust, secondhand smoke, and nearby traffic pollution. This model helps show that several factors together contribute to disease risk, rather than just one single cause.
web of causation
Transfer of infection from parent to offspring
vertical transmission
The six components of the chain of infection are...
pathogen, reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host
Infections like rabies or avian flu spread from animals to humans through this type of transmission
Zoonotic Tranmission
A newborn receives antibodies from the mother through breast milk, giving temporary protection against infections
passive immunity
Pre pathogenesis uses which intervention
primary
Passive acquired immunity is short or long term
short
The pathogenesis component of the stage of disease uses which types of intervention
secondary and tertiary
A mosquito bites an infected person and later bites Lisa, transmitting malaria to her
Vector-borne transmission
John gets a flu shot every year so his body can produce antibodies without actually getting the illness
Active immunity
Which component of the chain of infection does respiratory secretions belong to
portal of exit
After being exposed to rabies from an animal bite, a patient receives an injection of ready-made antibodies to provide immediate protection while the body develops its own immune response.
Passive immunity
Name the four components of the wheel of causation
Genetic Core
Biological Environment
Psychological Environment
Social Environment
In a remote village, villagers contract cholera from contaminated river water, which also spreads quickly to nearby towns via trade routes.
Vehicle-borne tranmission
A person who had cowpox in the past is now protected against smallpox because the viruses are related.
Cross immunity
During flu season, a student infected with influenza coughs in class. The virus lands on a shared desk and doorknob. Another student touches these surfaces and then rubs their eyes, later developing flu symptoms.
Agent: Influenza virus
Reservoir: Infected student
Portal of exit: Droplets from cough
Mode of transmission: Contaminated surfaces (fomite/direct contact)
Portal of entry: Touching eyes/nose
Susceptible host: The healthy student who touched the surfaces
Despite being exposed to a new strain of bacteria at work, Jordan doesn’t get sick. His intact skin, mucous membranes, and inflammatory response stop the bacteria before infection develops. No vaccines or prior illness were involved.
Natural immunity