Principles of Disease Flashcards
Mutualism
Microbe helps the host
Commensalism
No perceived benefit/cost to the host
Parasitism
Hurt the host
Pathology
Study of disease. Pathogens (microbes that harm the host)
Etiology
Cause of a disease
Pathogenesis
The manner in which a disease develops
Infection
The growth of pathogens in/on the host. Doesn’t always become disease, the beginning of infection doesn’t cause a perceived difference in the state of health
Disease
Any change in the state of health
Infectious Disease
When an infection results in any change in the state of health
Symptoms
Subjective changes in body function that are felt by a patient as a result of disease
Signs
objective changes in a body that can be measured or observed as a result of disease
Duration
Average time that individuals have a disease from diagnosis until they are either cured or die
Acute disease
Symptoms develop rapidly but has a short duration
Chronic disease
Symptoms develop slowly, likely to last for a long period
Subacute disease
Intermediate between acute and chronic
Latent disease
causative agent is inactive for a time but then activates and produces symptoms
Incubation period
No signs or symptoms
Prodromal period
Mild signs or symptoms
Communicable disease
Transmit from human to human
Noncommunicable Disease
Infections that do not spread human to human
Zoonosis
Spread from animals to humans
Reservoir
Animals, humans, objects, or habitats where pathogen is naturally found
Vector-borne transmission
Insect/arthropod
Vertical Transmission
Passed mother to child. In utero/delivery/breastmilk
Epidemiology
The monitoring and controlling disease occurrence to promote public health
John Snow (1848-1849): Mapped the occurrence of cholera in London (“father of epidemiology”)
Ignaz Semmelweis (1846-1848): Showed that handwashing decreased the incidence of puerperal sepsis
Florence Nightingale (1858): Showed that improved sanitation decreased the incidence of epidemic typhus
Endemic
Routinely detected in a population or region (e.g. common cold)
Epidemic
Widespread disease outbreak in a particular region/specific timeframe
Pandemic
Epidemic that spreads to include numerous countries
Emerging pathogen
Newly identified agents or pathogens that previously caused only sporadic cases
Endogenous Source
Pathogen came from one’s own body
Exogenous Source
External to host
Reemerging pathogen
Infectious agent that was under control but is now resurfacing
Incidence
Number of people who develop a disease during a particular time period
Prevalence
Number of people who have a disease at a specified time, regardless of when it first appeared (both old and new cases)
Reproductive number (R0)
Average number of people who will contract a disease from one infected individual
Case fatality ratio (C F R)
Proportion of individuals diagnosed with a disease who die from that disease within a certain period of time
Notifiable Disease
Disease that the CDC recommends reporting to government health agencies
Reportable Disease
Diseases on a state or local tracking list
Morbidity Rate
Number of people affected in relation to the total population in a given time period
Mortality Rate
Number of deaths from a disease in relation to the total population in a given time period
Describe how Robert Koch helped shape the germ theory of disease and list his postulates of disease
Robert Koch (1843-1910). German physician. Identified Bacillus anthracis as the cause of anthrax, developed Koch’s Postulates (methodology to determine the specific etiological agent of an infectious disease).
- Every diseased individual harbors the pathogen
- Pathogen can be isolated and cultured in the lab (sometimes culturing is very hard)
- Take a pure culture of the isolate and inject into healthy individuals of the same population, confirm they contract the same disease
- Confirm the same pathogen is present by isolating from new diseased individual
Epidemiological Triangle
Overlap of host, environmental, and etiological agent factors
Contagious Disease
Easily transmitted from one host to the next
Asymptomatic Carriers
No signs/symptoms of infection
Incubatory Carriers
Transmit the pathogen during the prodromal phase (before signs and symptoms begin)
Convalescent Carriers
Have recovered but remain capable of transmitting the pathogen to others
Chronic Carriers
Harbor pathogen for months-years after initial infection and are often referred to as being “colonized”
Compare communicable/noncommunicable disease
Communicable means it spreads from person to person, noncommunicable means it doesn’t
Compare acute/chronic disease
In acute disease, symptoms come on rapidly and the disease usually resolves relatively quickly, but in chronic disease, the symptoms come on slowly and the disease lasts a long time
Compare endemic/sporadic disease
Compare pandemic/epidemic disease
An epidemic is widespread disease in a particular region in a specific time frame, and a pandemic is an epidemic that spans multiple countries
Compare endogenous/exogenous
Endogenous means it came from the host (AKA you got the pathogen from your own body), while exogenous means it came from an external source
Describe the various modes of transmission: Direct Contact
Person to Person Transmission: touching, saliva, sex
Zoonotic Transmission: contact with animals/product
Includes bites/scratches
Vertical Transmission: Passed mother to child
In utero/delivery/breastmilk
Describe the various modes of transmission: Indirect Contact
Airborne Transmission: airborne particles carry pathogen; travel far
Droplet Transmission: droplets expelled from nose/mouth; travel 3-18 ft
Foodborne Transmission: food and/or water carry pathogen; AKA (oral-fecal transmission)
Vector-borne Transmission: insect/arthropod
Put the following in proper sequence, according to the pattern of disease: period of decline, period of convalescence, period of illness, prodromal period, incubation period
- Incubation period
- Prodromal period
- Period of illness
- Period of decline
- Period of convalescence
Contrast human, animal, and nonliving reservoirs, and give one example of each
Define healthcare-associated infections and explain their importance
List several probable reasons for emerging infectious diseases, and name one example for each reason
