4. how viruses are transmitted Flashcards
(33 cards)
define incidence
number of new infections over a period of time
define prevalence
total number of people infected in a population, new and old, over a period of time
define endemic
normal number of cases in a population. the number can be high, low, and even seasonal
define epidemic
an increase in the average number of cases in an area
define pandemic
an epidemic that has spread to several countries or continents
define Ro - reproductive number
on average, how many people on infected person will infect in a susceptible population
define communicable
an infectious disease transmitted from one source to another
what are the ways a disease can be communicable
- person to person
- animal to person
- fomite to person (phone, pen, shopping cart handle)
define contagious
derived from contact. considered a very communicable disease spread by contact or proximity to an infected person
how is a contagious diesease transmitted
- respiratory droplets
- fecal/oral
- contact with skin or abrasion
define non-contagious infections
still communicable but not by casual contact.
how are non-contagious infections transmitted
- secual contact - semen, vaginal fluid, or genital lesions
- parenteral/injection - shared needles
- congenital - mother to fetus
- perinatal - pregnancy (after 24 weeks), during or shortly after birth
- arboviral - mosquito, tick
- zoonotic - transfer from infected non-human animals to humans
winter/spring is the season for which generally types of viruses
enveloped and transmitted through respiratory route and many gastroenteric viruses
summer/early fall is the peak season for which viruses
arboviruses and picornaviruses
define incubation period
time from infection until symptoms appear
define latent period
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
define infectious phase
when infected individual can spread the disease to others.
- person can become infectious before symptoms appear
define prodromal phase
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
the iceberg concept of infection from top to bottom:
death
severe disease
mild illness
infection without symptoms
exposure without infection
define horizontal transmission
human to human
define vertical transmission
from mother to infant
define indirect zoonotic spread
with insect intermediary called the vector
define direct zoonotic spread
from infected non-human animal to the human
generalized infection is the same as ______
systemic
