Microbiology Chapter 14

study of disease

cause of disease

development of disease

invasion of the body by pathogens

abnormal state in which the body is not performing normal functions

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

present for days, weeks or months

competition between microbes

1. competing for nutrients

2. producing substances harmful for invading microbes

3. affecting pH and available oxygen

relationship between normal microbiota and host

one organism benefits, and the other is unaffected

both organisms benefit

one organism benefits at the expense of others

# of people who develop a disease during a time period

# 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)

occurs only occasionally

constantly present in population

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

worldwide epidemic

symptoms develop rapidly but lasts a short time

symptoms develop slowly

intermediate between acute and chronic disease

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

immunity in most of a population

how many people the average person infects

incubation disease

prodromal disease

period of illness

period of decline

period of convalescence

initial infection

first signs and symptoms

pre-symptomatic

infectious

when the disease is more severe

signs and symptoms will decline

death

body returns to its predeceased state

carriers: inapparent infections/ latent diseases

zoonoses: diseases transmitted from animals to humans

soil and water

human to human

close association of infected → susceptible host

mother → fetus or newborn at birth

spreads to a host by a nonliving object called a fomite

transmission via airborne droplets

less than 2 meters

environment to human

airborne

waterborne

foodborne

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

examples, anthropods, fleas, ticks, mosquitoes

transmit disease by two methods… mechanical and biological

arthropod carries pathogen on its feet

pathogen reproduces in the vector, transmitted via bites or feces

acquired while receiving treatment in a health care in facility

nosocomial infections

standard precautions

transmission-based precautions

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

droplet precautions (e.g. masks)

airborne precautions (e.g. ventilation)

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

physicians are required to report occurrence

# people affected in relation to total population in given time

# of deaths in relation to population in a given time

# affected / total population

# deaths / # affected