Communicable diseases: introduction Flashcards
define: communicable disease
caused by an infectious agent, which is transmitted from one organism to another
3 requirements/steps to infection
- infectious agent must be present
- infectious agent must be transmitted to the host
- infectious agent must invade the host and multiply
step 1?
infectious agent must be present
what are the 4 types of infectious agents
bacteria
virus
parasite (roundworm, nematode)
fungi (and their toxic products)
step 2?
infectious agent must be transmitted to the host
define host
person/animal that the pathogen can survive and reproduce in, under normal conditions
name the 4 modes of transmission
direct transmission indirect transmission -vehicle borne -vector borne -airborne
direct transmission
- define
- examples
- how to control
source –> host
through sex, kissing, touching etc
gloves, condoms
vehicle borne transmission
-define
source –> food, clothes, bed, cooking utensils –> individual
airborne transmission
- define
- how to control
source –> dust particles/fungal spores –> individual
wear face mask
vector borne
- define
- how to control
source –> vector (mosquito, bat) –> individual
clothes, nets, mosquito repellent
does the environment play a role in infectious agent transmission?
yes
describe some environmental factors
temperature, sanitation, air/water quality, house crowding
step3:
the infectious agent must invade the host and multiply
describe the first line of defence that must be invaded
skin
mucous membranes - GI and resp tract
what happens once inside the body that causes infection
local cellular injury due to
- competitive metabolism
- toxin production
- intracellular replication
- antigen-antibody response
what is a way that prevents the infectious agent from having deterious effects even once it’s in the internal environment?
immunisation and vaccination
define: vaccination
injection of inactivated/weakened pathogens into person
what microorganisms are vaccination effective for? what aren’t they?
bacteria and viruses. not parasites
new vaccine being made?
malaria
what macro process do vaccines enable?
herd immunity
define: immunisation
physical response to the vaccination (injection of pathogens) which results in antibodies being made.
define: virulence
strengh of disease
define: infection
when an infectious agent invades the body and multiplies. results in local cellular injury - toxin production, competitive metabolism, intracellular replication and antigen-antibody response
define: primary pathogen
pathogen itself can cause disease
define: opportunistic pathogen
when immune system is weakened, then pathogen can cause disease
acute vs chronic disease/
last for short or long time
in relation to disease course
-what two terms relate to the person being able to SPREAD the disease (rather than show symptoms?)
period of latency
period of communicability
define: period of latency
having infection, but not being able to spread
define: period of communicability
having infection and being able to spread
in relation to disease course
-what two terms relate to the person showing SYMPTOMS of the disease (rather than spreading it?)
incubation period
disease period
define: incubation period
has infection but doesn’t show symptoms
define: disease period
has infection and shows symptoms
define: source of infection
site from which pathogen is transmitted to host (eg food)
define: reservoir of infection
site where pathogen can survive and multiply (eg. gut mucosa)
notifiable diseases: what is the name of the scheme
national notifiable diseases surveillance scheme
what does the national notifiable diseases surveillance scheme require
for particular communicable diseases to be reported and monitored by law
what are they? 2xC 2xH 3xM 2 miscellaneous
cholera chicken pox hiv hepatitis measles mumps malaria tetanus infuenza/avian flu
candidates for eradication must fit what 3 requirements
- effective intervention to interrupt transmission must exist
- tests for it much be accurate (high sensitivity and specificity)
- there must be no animal reservoir
