Chapter 15 Flashcards
epidemiology
study of factors and mechanisms involved in the frequency and spread of diseases and other health-related problems within populations of humans, other animals, or plants
number of new cases contracted within a set population during a specific time period
(# new cases) / (# people at risk)
incidence
total of people infected within a population at any time
old + new cases) / (# people at risk
prevalence
number of individuals with a disease during a set period of time divided by the total population
morbidity
number of deaths due to a specific disease during a specific period of time divided by the total population
mortality
disease that normally occurs at a relatively stable frequency within a given population or geographical area
endemic
disease that appears as a few scattered cases with a population or geographical area
sporadic
disease that occurs with a greater than usual frequency within an area or population
epidemic
when an epidemic occurs in one or more continents at the same time
pandemic
arise from contact with contaminated substance
common source outbreak
amplification of infection as a result of person-to-person contact
propagated epidemics
holding tanks; sites where pathogens exist and are maintained as source of infection
reservoirs
3 types of reservoirs of infection for human disease
- Human carriers
- Animal reservoirs
- Nonliving reservoirs
Human carriers
- humans with active disease are reservoirs of infection
- carries- asymptomatic but infective
- common cold viruses by inhalation of sneezed particles
- HIV direct sexual contact or injection of contaminated blood products
Animals reservoirs
- pathogens that infect domesticated or sylvatic animals can infect humans
- routes: direct contact with animals, animal waste, eating animals, blood-sucking arthropods
nonliving reservoirs
- soil - fecal contamination; endospores
- food
- water
example of human reservoir
S. aureas from normal flora or infected persons by contact
example of animal reservoirs
rabies and plague
example of nonliving reservoirs
coccidiodides immitis - airborne fungal spores are inhaled
vibrio cholera - ingested by contaminated drinking water
zoonotic disease
disease spread from animal host to humans
3 methods of disease transmission
- Contact
- Vehicle
- Vector
direct contact
- person-to-person
- placental
- fecal-oral (#1 in world)
indirect contact
fomites
droplet transmission
mucus droplets
-less than 1 meter
person-to-person, touching, handshaking, animal bite, sexual intercourse is what kind of contact
direct
agent of disease is transmitted from its reservoir to a susceptible host by means of nonliving object
indirect contact
bedding, dishes, money, thermometer, contaminated needles is what kind of contact
indirect
microbes spread in aerosol droplets discharge in air by sneezing, coughing, laughing, or talking is what kind of transmission
droplet
spread by water contaminated with untreated sewage is what kind of vehicle transmission
waterborne
pathogens transmitted in or on food that has been improperly prepared, cooked, or stored is what kind of vehicle transmission
food-borne
spread of agents in aerosol droplets that travel more than 1 meter from reservoir or host is what kind of vehicle transmission
airborne
biological vector transmission
specific relationship between vector and pathogen
-host is part of pathogens life cycle
mechanical vector transmission
no direct relationship
-passive transport of pathogens on insects feet or other body parts
portion of individuals in a community or population who are immune to a particular disease
herd immunity
what is reemergence
not having kids vaccinated properly
ways public health agencies work to limit the spread of disease
- immunizations
- inspections
- water and sewage treatment
infection disease that are potentially harmful to publics health and must be reported by physicians
nationally notifiable disease
portals of exit
eyes (tears), ears (wax), nose, mouth, skin, blood, vaginal secretions/semen, urine, feces, sweat
compromised host
more susceptible host
conditions that create opportunities for normal microbiota to cause disease
- failure of host normal defenses
- introduction of the organisms into unusual body parts
- disturbances in normal microflora
universal precautions
designed by the CDC to reduce the risk of spreading blood borne pathogens
blood, semen, vaginal, CSF
nosocomial infection
infection acquired in the hospital or other medical facility
microbes that enter patient from environment (external)
Exogenous infection
infection caused by microbes from patients own microflora
endogenous infection
infection caused by medical procedure
tatrogenic infection
number 1 nosocomial infection
urinary tract
types of contact transmission
direct, indirect, droplet
inanimate objects that inadvertently transmit pathogens
fomites
types of vehicle transmission
airborne, waterborne, body-fluid, food-borne
body fluid transmission
blood, urine, salvia, semen
used to prevent any body fluid from contacting conjunctive, breaks in skin, breaks in mucous membrane
universal precautions
types of vector transmission
biological and mechanical
patient with communicable disease is prevented from having contact with general population
isolation
separation of healthy humans from the general population when they have been exposed to a communicable disease
quarantine
- increase herd immunity
- decrease death from infection disease
immunization
vector control
insect and rodent control
sites od nosocomial infections
urinary tract, surgical wounds, respiratory tract, skin, blood, gastrointestinal tract, central nervous system
nosocomial infection prevention and control
- surveillance of nosocomial infections in patient and staff
- microbiology lab
- isolation procedures
- accepted procedures for catheters and respirators
- sanitation program
- nosocomial disease education program
