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Disease, Epidemiology and Public Health Cheat Sheet (DRAFT) by

microbiology study note

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Epidem­iology defini­tions

morbidity
state of being diseased
morbidity rate
% of diseased indivi­duals in a population
mortality rate
% of population that has died of disease
epidem­iology
study of how diseases originate and how that are passed through commun­ities
epidem­iol­ogists
must take into account time, place, # of people, frequency of disease when studying diseases.
incidence
fraction of a population that contracts a disease during a specific time
prevalence
fraction of a population having a specific disease at a given time
sporadic disease
disease that occurs occasi­onally in a popula­tion.
endemic disease
disease constantly present in a popula­tio­n(c­old).
epidemic disease
disease acquired by many hosts in a given area in a short time (flu).
pandemic disease
world wide epidemic (covid).

portals of entry

skin
parasitic worms and fungi
mucous membranes
easiest way for pathogens to enter body
parental route
pathogens deposited directly into tissues

develo­pment of disease

incubation period
between infection and first sign and symptom
prodromal period
relatively short period with mild and early symptoms
illness
disease most severe, patient dies if immune response not sufficient
decline
patient vulnerable to second infection at this time. signs and symptoms subside
conval­secence
regaining of strength
 

important history

Louis Pateur
germ theory
Robert Koch
cause of disease
Joseph Lister
control of disease
John snow
mapped cholera in London
Ignaz Semmelweis
proved hand washing effective in reducing death during child birth
Florence Nighti­ngale
Showed improved sanitation decreased the incidence of epidemic typhus

patterns of disease

1. source of infection (reservoir
2. transm­ission
3. invasion (patho­gen­esis)

transm­ission of disease

direct contact transm­ission
person to person by physical contact
indirect contact transm­ission
reservoir to host by non living object
droplet contact transm­ission
microbes spread in droplet nuclei
vehicle transm­ission
transm­ission by inanimate reservoir
mechanical vector transm­ission (passive)
vector physically carries disease and drops on host
biological vector transm­ission (active)
spreads microbes through inside vector

severity of disease

acute disease
symptoms develop rapidly but last short amt of time
chronic disease
disease develops slowly but lasts long time
subacute disease
interm­ediate between acute and chronic
latent disease
is dormant but can have active periods

limit disease transm­ission

enforcing standards of cleanl­iness
work to reduce # of disease vectors and reservoirs
establish and enforce immuni­zation schedules
locate and treat indivi­duals exposed to contagious pathogens
establish isolation and quarantine measures to control the spread of pathogens
educate public
 

epidem­iology data

descri­ptive
(who, what, when where) data that describes occurrence of disease
analytical
(why) comparison of diseased and healthy
experi­mental
(hypot­hesis and answer) controlled experi­ments used to study disease

koch's postulates

microbes cause specific disease
bacillus anthracis
cultured bacteria still infectious

reservoirs of infection

human reservoirs
transmit directly or indirectly to others
animal reservoirs
direct contact with animal or pet waste, contam­inated food and water, consuming infected products
non living reservoirs
soil, water if contam­inated, food

virulence measured

ID50/ infectious dose
how many microbes needed to make 50% of population sick
LD50/ lethal dose
how many lethal doses needed to kill 50% of population

extent of host involve

local infection
limited small area of body (stays localized)
systemic infection
an infection throughout the body
focal infection
local infection turned into systemic infection

HAIs

nosocomial infection or HAIs
infection acquired in health acre facility
exogenous
acquired from health care enviro­nment
endogenous
normal microbiota become opport­unistic because of hospit­ali­zation or treatment
iatrogenic
"­doctor induce­d". use of catheters and invasive diagnostic proced­ures, surgery