nsi 2

Question 1

w i Reservoir

and examples

Answer 1

habitat in which the agent normally lives, grows, and multiplies. Reservoirs include humans, animals, and the environment

Question 2

wi a carrier

Answer 2

is a person with inapparent infection who is capable of transmitting the pathogen to others.

Question 3

wi Asymptomatic or passive

Answer 3

healthy carriers are those who never experience symptoms despite being infected

Question 4

Incubatory carriers

Answer 4

those who can transmit the agent during the incubation period before clinical illness begins

Question 5

Convalescent carriers

Answer 5

are those who have recovered from their illness but remain capable of transmitting to others

Question 6

Chronic carriers

Answer 6

who continue to harbor a pathogen such as hepatitis B virus or Salmonella Typhi, the causative agent of typhoid fever, for months or even years after their initial infection

Question 7

why are carriers more likely to transmit than symptomatic

Answer 7

they do not realize they are infected, and consequently take no special precautions to prevent transmission.

Question 8

Humans are also subject to diseases that have animal reservoirs

Answer 8

Many of these diseases are transmitted from animal to animal, with humans as incidental hosts

Question 9

zoonosis

Answer 9

infectious disease that is transmissible under natural conditions from vertebrate animals to humans

Question 10

Portal of exit

Answer 10

Portal of exit is the path by which a pathogen leaves its host

Question 11

Modes of transmission

Answer 11

Direct

Direct contact
Droplet spread
Indirect

Airborne

Vehicleborne. infectious agent include food, water, biologic products (blood),
Vectorborne (mechanical or biologic)

Question 12

what happen in direct transmition

Answer 12

In direct transmission, an infectious agent is transferred from a reservoir to a susceptible host by direct contact or droplet spread.

Question 13

Portal of entry

Answer 13

The portal of entry refers to the manner in which a pathogen enters a susceptible host. The portal of entry must provide access to tissues in which the pathogen can multiply or a toxin can act

Question 14

Susceptibility of a host depends on

Answer 14

genetic or constitutional factors, specific immunity, and nonspecific factors that affect an individual’s ability to resist infection or to limit pathogenicity. An individual’s genetic makeup may either increase or decrease susceptibility

Question 15

examples Nonspecific factors

Answer 15

include the skin, mucous membranes, gastric acidity, cilia in the respiratory tract, the cough reflex

Question 16

what can increase risk

Answer 16

disrupting host defenses include malnutrition, alcoholism, and disease or therapy that impairs the nonspecific immune response

Question 17

Knowledge of the portals of exit and entry and modes of transmission provides

Answer 17

a basis for determining appropriate control measures.

Question 18

Interventions are directed at:

Answer 18

Controlling or eliminating agent at source of transmission
Protecting portals of entry
Increasing host’s defenses
mode of transmission. Interruption of direct transmission may be accomplished by isolation of someone with infection

Question 19

For airborne diseases prevention

Answer 19

strategies may be directed at modifying ventilation or air pressure, and filtering or treating the air

Question 20

To interrupt vectorborne transmission

Answer 20

measures may be directed toward controlling the vector population, such as spraying to reduce the mosquito population.

Question 21

The concept of herd immunity suggests

Answer 21

if a high enough proportion of individuals in a population are resistant to an agent, then those few who are susceptible will be protected by the resistant majority, since the pathogen will be unlikely to “find” those few susceptible individuals. 85% to 90%

Question 22

One problem is that

Answer 22

in highly immunized populations, the relatively few susceptible persons are often clustered in subgroups defined by socioeconomic or cultural factors. If the pathogen is introduced into one of these subgroups, an outbreak may occur.

Question 23

HAIs

Answer 23

infections that patients get while receiving treatment for medical or surgical conditions,

Question 24

Risk factors for HAIs can be grouped into three general categories

Answer 24

medical procedures and antibiotic use, organizational factors, and patient characteristics.5

The behaviors of health care providers and their interactions with the health care system also influence the rate of HAIs.

Question 25

preventing HAI

Answer 25

proper education and training of health care workers adoption of best practices ( infection control, hand hygiene, attention to safety culture, and antibiotic stewardship)
Examples of best practices by a health care provider include careful insertion, maintenance, and prompt removal of catheters, careful use of antibiotics.
decolonization of patients with an evidence-based method to reduce transmission of MRSA in hospitals.7