Ch 16 Epidemiology & Nosocomial Infections

Question 1

reservoirs of infection

Answer 1

*sites in which organisms can persist and maintain their ability to infect.

Question 2

human reservoirs

Answer 2

*humans with active infections, reservoirs because they easily transmit organisms to other humans

Question 3

carriers

Answer 3

*individuals who harbor an infectious agent without having observable clinical signs or symptoms

Question 4

animal reservoirs

Answer 4

*zoonosis disease- diseases that can be transmitted under natural conditions to humans from other vertebrate animals.

Question 5

portals of entry

Answer 5

*sites at which microorganisms can enter the body
*common portals: skin, mucous membrane, digestive, respiratory, urogenital systems
*openings such as ears, nose, mouth, eyes, anus, urethra, vagina allow microbes to enter.
*respiratory system- enter thru inhaled air, droplets, dust particles.
*digestive system- ingested thru contaminated food, water, utensils, hands
*entry through fluid discharges from mucous membranes, sexual intercourse,
*entry through damaged tissue: bites, burns, injections, wounds
*infections, viruses, congenital infections can enter across the placenta

Question 6

portals of exit

Answer 6

*how infectious agents get out of their hosts is important to spread of disease.
*generally pathogens exit through body fluids or feces.
*respiratory pathogens exit through saliva, coughed, sneezed, spit, speaking.
*gastrointestinal pathogens exit through fecal matter
*urine and semen can carry urogenital pathogens
*sexually transmitted diseases exit urogenitally.
*blood and milk can transmit pathogens

Question 7

modes of disease transmission

Answer 7

*in order for infectious disease to spread, pathogens must be transmitted from a reservoir or portal of exit to a portal of entry.
*several modes: contact transmission, transmission by vehicles, transmission by vectors

Question 8

Mode: Contact Transmission

Answer 8

types:
direct contact,
indirect contact,
droplet

Question 9

direct contact

Answer 9

*requires body contact between individuals,
*horizontal transmission: thru hand shake, kiss, touching sores, sexual contact.
*vertical transmission: pathogens passed from parent to offspring in an egg or sperm, across placenta, breast milk, birth canal.

Question 10

indirect contact (fomite)

Answer 10

*non-living objects that can harbor and transmit an infectious agent.

Question 11

droplet

Answer 11

*when a person coughs or sneezes, or speaks near others and they inhale particles directly
*droplets consist of dried mucus, which protects microorganisms embedded in it.
*droplets that travel less than 1 meter from a sneeze or cough to a host are not airborne

Question 12

Mode: Vehicle Transmission

Answer 12

*nonliving carrier of an infectious agent from its reservoir to a susceptible host.
*common vehicles: water, air, food, blood, body fluid, intravenous fluid

Question 13

waterborne

Answer 13

*do not grow in pure water, survive transit in water with small quantities of nutrients in polluted water
*usually thrive in contaminated or untreated water/ inadequately treated sewage
*can be prevented by proper treatment of water and sewage.

Question 14

airborne

Answer 14

*transient from soil, water, plants, animals
*do not grow in air, but some reach new hosts through air
*airborne if they travel more than 1 meter through the air

Question 15

foodborne

Answer 15

*transmitted in foods that are inspected improperly, processed unsanitarily cooked improperly, or refridgerated poorly.
*likely to produce gastrointestinal issues

Question 16

Mode: Vector Transmission

Answer 16

*vectors: living organisms that transmit disease to humans
*most vectors are arthropods: fleas, ticks, flies, lice, mosquitos, however can be mechanical or biological.

Question 17

mechanical vectors

Answer 17

*insects act as mechanical vectors when they transmit pathogens passively on their feet and body parts

Question 18

biological vectors

Answer 18

*insects act as biological vectors when they transmit pathogens actively, that is, the infectious agent must complete part of its lifecycle in the vector before the insect can transmit the infective form of the microbe
*

Question 19

nosocomial infection

Answer 19

*infections acquired in a hospital or other medical facility
*can be infections acquired by patients or by staff
*2million hospitalized pts (10%) acquire an infection that increases their risk of death each year
*100,000 people per year die of nosocomial infections

Question 20

source of infection

Answer 20

exogenous & endogenous

Question 21

exogenous

Answer 21

*infections from other people outside of the patients environment
*transmitted from insects or fomite to patients

Question 22

endogenous

Answer 22

*infections from the patients own normal microflora

Question 23

susceptibility and transmission

Answer 23

*patients in hospitals are much more susceptible to infection
*more likely to have cuts/scrapes/lesions/wounds for infection to transmit
*breaks in mucous membranes also cause infection transmission
*some organisms can be transmitted by more than one route

Question 24

universal precautions

Answer 24

*guidelines used to reduce risk to patients by:
*decreasing the use of contaminated equipment
*having staff wash hands and use supplies that will reduce the risk of infection

Question 25

preventing and controlling nosocomial infection

Answer 25

*handwashing *maintain sterile equipment *maintain sterile field when performing invasive procedures