Microbiology Chapter 14

pathology

study of disease

etiology

cause of disease

pathogenesis

development of disease

infection

invasion of the body by pathogens

disease

abnormal state in which the body is not performing normal functions

normal microbiota

permanent colonize host, do not cause disease (under normal conditions)

transit microbiota

present for days, weeks or months

microbial antagonism (competitive exclusions)

competition between microbes

normal microbiota protect the host by

1. competing for nutrients
2. producing substances harmful for invading microbes
3. affecting pH and available oxygen

symbiosis

relationship between normal microbiota and host

commensalism

one organism benefits, and the other is unaffected

mutalism

both organisms benefit

paratism

one organism benefits at the expense of others

incidence

\# of people who develop a disease during a time period

prevalence

\# of people who develop or have a disease at a specified time, regardless of when it first occurred

takes into account both old and new cases)

sporadic disease

occurs only occasionally

endemic disease

constantly present in population

epidemic disease

acquired by many people in a given area in a short time

pandemic

worldwide epidemic

acute disease

symptoms develop rapidly but lasts a short time

chronic disease

symptoms develop slowly

subacute disease

intermediate between acute and chronic disease

latent disease

causative agent is inactive for a time but then activates and produces symptoms

herd immunity

immunity in most of a population

what is a R° value

how many people the average person infects

5 stages of development of disease

incubation disease

prodromal disease

period of illness

period of decline

period of convalescence

incubation period

initial infection

first signs and symptoms

prodromal period

pre-symptomatic

infectious

period of illness

when the disease is more severe

period of decline

signs and symptoms will decline

what is exception when period of illness does not lead to period of decline

death

period of convalescence

body returns to its predeceased state

human reservoirs

**carriers:** inapparent infections/ latent diseases

animal reservoirs

**zoonoses:** diseases transmitted from animals to humans

give two examples of non-living reservoirs

soil and water

contact transmission is…

human to human

direct contact transmission

close association of infected → susceptible host

congenital transmission

mother → fetus or newborn at birth

indirect contact transmission

spreads to a host by a nonliving object called a **fomite**

droplet transmission

transmission via airborne droplets

less than 2 meters

vehicle transmission is…

environment to human

what are three examples of vehicle transmission

airborne

waterborne

foodborne

ID 50

infectious dose for 50% of a sample population, measures virulence of a microbe

vectors

examples, anthropods, fleas, ticks, mosquitoes

transmit disease by two methods… mechanical and biological

mechanical transmission

arthropod carries pathogen on its feet

biological transmission

pathogen reproduces in the vector, transmitted via bites or feces

healthcare associated infections are…

and also known as…

acquired while receiving treatment in a health care in facility

nosocomial infections

what are two types of universal precautions

standard precautions

transmission-based precautions

what are three types of transmission based precautions (give examples)

contact precautions (e.g. gloves and frequent sanitation)

droplet precautions (e.g. masks)

airborne precautions (e.g. ventilation)

epidemiology

study of where and when diseases occur and how they are transmitted in populations

notable infectious disease

physicians are required to report occurrence

morbidity rate (incidence)

\# people affected in relation to total population in given time

mortality rate

\# of deaths in relation to population in a given time

incidence= (math)

\# affected / total population

mortality= (math)

\# deaths / # affected