4. how viruses are transmitted

Question 1

define incidence

Answer 1

number of new infections over a period of time

Question 2

define prevalence

Answer 2

total number of people infected in a population, new and old, over a period of time

Question 3

define endemic

Answer 3

normal number of cases in a population. the number can be high, low, and even seasonal

Question 4

define epidemic

Answer 4

an increase in the average number of cases in an area

Question 5

define pandemic

Answer 5

an epidemic that has spread to several countries or continents

Question 6

define Ro - reproductive number

Answer 6

on average, how many people on infected person will infect in a susceptible population

Question 7

define communicable

Answer 7

an infectious disease transmitted from one source to another

Question 8

what are the ways a disease can be communicable

Answer 8

1. person to person
2. animal to person
3. fomite to person (phone, pen, shopping cart handle)

Question 9

define contagious

Answer 9

derived from contact. considered a very communicable disease spread by contact or proximity to an infected person

Question 10

how is a contagious diesease transmitted

Answer 10

1. respiratory droplets
2. fecal/oral
3. contact with skin or abrasion

Question 11

define non-contagious infections

Answer 11

still communicable but not by casual contact.

Question 12

how are non-contagious infections transmitted

Answer 12

1. secual contact - semen, vaginal fluid, or genital lesions
2. parenteral/injection - shared needles
3. congenital - mother to fetus
4. perinatal - pregnancy (after 24 weeks), during or shortly after birth
5. arboviral - mosquito, tick
6. zoonotic - transfer from infected non-human animals to humans

Question 13

winter/spring is the season for which generally types of viruses

Answer 13

enveloped and transmitted through respiratory route and many gastroenteric viruses

Question 14

summer/early fall is the peak season for which viruses

Answer 14

arboviruses and picornaviruses

Question 15

define incubation period

Answer 15

time from infection until symptoms appear

Question 16

define latent period

Answer 16

person is infected, but no virus is shed from the body. time from infection until you become infectious and capable of spreading the disease to others

Question 17

define infectious phase

Answer 17

when infected individual can spread the disease to others.
- person can become infectious before symptoms appear

Question 18

define prodromal phase

Answer 18

generalized symptoms that can occur in many viral infections BEFORE specific symptoms arise that might aid in diagnosis
- ex: time someone feels sick before the measles-defining rash

Question 19

the iceberg concept of infection from top to bottom:

Answer 19

death
severe disease
mild illness
infection without symptoms
exposure without infection

Question 20

define horizontal transmission

Answer 20

human to human

Question 21

define vertical transmission

Answer 21

from mother to infant

Question 22

define indirect zoonotic spread

Answer 22

with insect intermediary called the vector

Question 23

define direct zoonotic spread

Answer 23

from infected non-human animal to the human

Question 24

generalized infection is the same as ______

Answer 24

systemic

Question 25

does localized infection spread throughout the body

Answer 25

no, no viremia. some but not all infections of the respiratory tract/GI tract, eye , skin

Question 26

define viremia

Answer 26

virus present in the blood

Question 27

localized infection length of incubation time?

Answer 27

shorter incubation times, usually days

Question 28

which Ig more important in localized infection

Answer 28

IgA

Question 29

lifelong immunity present for localized infections?

Answer 29

not always lifelong immunity, sometimes shorter mucosal immunity

Question 30

generalized infection spread throughout the body?

Answer 30

yes. spreads through the body via blood or nervous system

Question 31

generalized infection length of incubation time?

Answer 31

longer incubation times, weeks to months

Question 32

which Ig more important in generalized infection

Answer 32

IgG

Question 33

lifelong immunity present for generalized infection?

Answer 33

yes. usually lifelong immunity