Chapter 14: Epidemiology Flashcards
human microbiome
microrgansims in the body
normal flora/ microbiome
healthy microrganisms in the body
probiotics
healthy microrganisms introduced into the body
symbiosis
mutualism
commensalism
parasitism
symbiosis- interaction of species with one another
mutualism- both organisms benefit
commensalism- one benefits where the other is unaffected
parasitism- one benefits where the other is harmed
oppertunistic pathogens
normal microbiota becoming pathogenic ex E.coli
microbial antagonism
competition between microbes
Koch’s postulates
1) pathogen present in every case of disease
2) pathogen isolated from the diseased host and grown in pure culture
3) pathogen must cause disease in healthy animal
4) pathogen must be shown to be the orignal pathogen
Exceptions to Koch’s postulates
- some pathogens cause multiple signs and symptoms (hard to trace signs and symptoms to microbes, ex. strep throat)
- diseases can be caused by multiple pathogens (hard to identify original pathogen, ex. pneumonia)
-some pathogens can’t be grown in pure culture (ex. sphyillis) - some pathogens only infect humans (difficult to test for cause because it is unethical, ex. small pox)
incidence number
number of people n a population who develop a disease during a time period
prevalance number
number of people who develop a disease at a specified time
acute disease
develops rapidly but lasts a short time (influenza)
latent infection
agent remains inactive until it produces symptoms (cold sores)
chronic infection
develops more more slowly for a longer time (cancer)
slow infection
progressively worse over time (mad cow disease)
local infection
pathogen limited to a small area (acne)
systemic infection
affects multiple organs, spreads via blood/lymph (HIV)
focal infection
travels through blood, only causes disease in one organ (Hep B)
subclinical infection
no noticable signs/symptoms
bacteremia
bacteria in the blood
viremia
viruses in the blood
toxemia
toxins in the blood
septicemia
multiplication of pathogens in the blood
stages of a disease
1) incubation- no signs/ symptoms
2) prodrome- mild signs/ symptoms
3) illness- most severe disease
4) decline- signs and symptoms decline
reservoirs for infection
pathogens survives, replicates, and transmits it to others
human
animal
nonliving
transmission of disease
1) Contact transmission
- Direct contact: horizontal (spread by physical contact) and vertical (spread from mother to baby)
- Indirect contact: fomites (inanimate objects that facilitates spread of a pathogen)
- Droplet transmission (short range droplet nuclei)
2) Vehicle transmission
- foodborne (inapproprately handled foods)
- waterborne (fecal contaminated water)
- airborne (small droplets that remain airborn for longtime)
3) Vector transmission
- mechanical (passive trasnsport of pathogen (fly landing on burger)
- biological (biting/ feeding on the host)
nosocomial infections
HAI, hospital acquired infections ex c.diff
why is there an expectation of increased incidents of emerging pathogens? (7)
1) globalization
2) growing immunocompromised population
3) climate change
4) expanding human population
5) decreading herd immunity
6) antibiotic resitant organisms
7) increasing recongnition of new clinical symptoms
what is herd immunity?
waning immune respnse in vasccinated individuals, unvaccinted or inadequately vaccinated populations
epidemiology
study of diseases nad its causes
tries to determine:
- causative agent
-source and/or reservoir of agent
- mechanism of transmission
-host and environmental factors that facilitate development of disease
-best control methods
communicable disease
disease that can spread from one host to another (ex chicken pox)
contagious disease
disease that is easily spread from one host to another (ex. COVID)
nonconmmunicable disease
disease that is not easily spread from one host to another (ex. botulism)
studies of epidemiology
1) desciptive: collection and analysis of disease
2) analytical- case control- healthy vs unhealthy
3) experimental- hypothesis- controlled experiments
who was John Snow? (1813-1858)
-used descriptive study
- responsible for determining a cause for chlorea
- suspected cholera was the cause of seage conmination
compared addresses of people with chloera and their source of water and concluded the place Broad Street pump was the chloera outbreak
who was Florence Nightingale? (1820-1910)
-used analytical study
-responsible for improving sanitary conditions in military hospitals
-sharply cut death rate and saved thousands of lives
-collected data for the amound of people dying for preventative measures
who was Ignaz Semelweis? (1818-1865)
- used experimental study
-responsible for recongnzing and documenting the incidence of puerperal fever in hospitals
-higher death rate of mothers who gave birth in hospitals compared to those by midwives because the physcians didnt wash their hands - kept careful records of the numbers of deaths from childbed fever compared to midwife aid
epidemic
outbreak that affects an entire region in a country or group of countries (measles)
pandemic
outbreak on a global scale (ex COVID 19)
endemic
disease that normally occurs in a particular geographic area within a certain period of time (flu)
