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Infectious Diseases and Outbreak Investigation Exam 2

Terms in this set (51)

infectious (communicable) disease
illness due to infectious agent or its toxic products that arise through transmission of that agent or its products from an infected person, animal, or reservior to a susceptible host either directly or indirectly through an intermediate plant or animal host, vector, or the inanimate environment
-pathogen that can be spread
Which continent has the highest mortality from infectious diseases
africa
parasitic disease
an infection caused by a parasite which is an organism that lives on or in a host organism and gets its food from or at the expense of its host
-there is a parasitic cycle and a parasite causes harm to the host it lives off of
epidemiologic triangle
used to describe eitology of infectious disease
-agent, host, environment
all come together to determine disease burden in an individual
agent
pathogen
a factor such as a microorganism, chemical, form of radiation whose presence, excessive presence or relative absence is essential for the occurrence of disease
-bacteria, virus, fungi, parasites, prions, rickettsia
host
a person or other living animal including birds and arthropods that affords subsistence or lodgement to an infectious agent under natural conditions.
-where pathogen naturally resides
environment
domain in which disease causing agents may exist, survive, or originate
ex. sunlight, water
infectivity
capacity of an agent to enter and multiply in a susceptible host and produce infection or disease
Virulence
severity of the disease produced.
whether the disease has severe clinical manifestations or is fatal in a large number of cases
great severity
high virulence ex. HIV
toxin
some infectious disease agents, instead of acting directly, produce a toxin that causes illness
-usually refers to a toxic substance made by living organisms ex. botulism is made from foodborne intoxications
host characteristics
immunity
other factors related to host responses
incubation period
subclinical illness
generation time
carrier status
immunity
hosts ability to resist infection by agent
-may be active or passive
active immunity
immunity that the host has developed as a result of natural infection with a microbial agent
-can be acquired from an injection of a vaccine that contains an antigen
antigen: substance that stimulates antibody formation ex. microbial agent
-usually of long duration (measured in years of own antibodies being formed)
passive immunity
immunity acquired from antibodies produced by another person or animal
-usually short duration
ex. given someone elses antibodies to prevent from getting sick, infants immunity from mothers breast milk, injections of antibodies contained in immune serums
herd immunity
resistance of an entire community to an infectious agent as a result of the immunity of a large proportion of individuals that community to the agent
incubation period
time interval between invasion by an infectious agent and the appearance of the first sign or symptom of the disease
-the period of communicability refers to the time during which an infectious agent can be transmitted directly or indirectly (when youre contagious)
latent period
time of when youre exposed to when you become infectious
subclinical infection
infection that does not show obvious clinical signs or symptoms
inapparent infection
ex. hep A in children
carrier
person or animal that harbors a specific infectious agent without discernible clinical disease, and which serves as a potential source of infection
-has disease and can spread for a long time
index case
used in epidemiologic investigation of disease outbreak to denote first case of disease
environment and infectious diseases
external environment comprises of these components
physical (drinking water)
climatologic (temp, moisture)
biologic
social (animals in area, near water?)
economic (urban, environment)
Endemic
infectious disease agent that is habitually present in an environment (geographic or population group)
plague is endemic among certain species of rodents in western US
reservoir
place where infectious agents normally live and multiply
can be humans, animals, insects, soils, or plants
-doesnt necessarily die from disease. ex. west nile naturally in bird population but is transmitted via mosquitoes
zoonotic
infection or infectious agent transmissible under natural conditions from vertebrae animals to humans
means of transmission of infectious agents
direct transmission
person to person
indirect transmission
vehicle borne infections (syringe
airborne infection (sneeze)
vector borne infection (mosquito)
portal of exit **
for an infected person, a portal of exit is the site from which the agent leaves the persons body
-respiratory passages
-alimentary canal
-genitourinary system
-skin lesions
portal of entry
site where the agent enters the body
-skin wound, respiratory system, mucus membranes (nose, eyes, mouth, lungs, vagina)
person to person transmission/direct
immediate transfer of infectious agents to a receptive portal of entry through which human or animal infection may take place
sex, sneeze, biting
indirect transmission
intermediary sources of infection such as vehicles, droplet nuclei (particles) and vectors
vehicle borne infections
contaminated non moving object
result from contact with vehicles
examples:fomites, unsanitary food, impure water
fomite
inanimate object that carries infectious disease agents
ex. doorknob, discarded tissues, workout equipment
airborne transmission
spread of droplet nuclei (particles) that are present in the air
ex. infections caused by stirring up dust that carries fungi or microbes
vector borne infections
vector is an animate, living insect or animal that is involved with the transmission of disease agents
transmission of an infectious disease agent may happen when the vector feeds on a susceptible host
*move and transmit disease
examples of vectors of infectious diseases
female louse
tick
norway rat
aedes aegypti mosquito
sexually transmitted diseases
acquired by sexual contact. the organisms that cause sexually transmitted diseases may pass from person to person in blood, semen, or vaginal and other bodily fluids
HIV/AIDS
gonococcal infections
chlamydial genital infection
gonorrhea disproportionately affects
blacks in the US
deep south most prevalent
gonorrhea take away
40% of the time there is a drug resistance
60% susceptible
foodborne illness
biologic agents of foodborne illness include bacteria, parasites, viruses, and prions (linked to mad cow disease)
transmitted via food
campylobacter
clostridium botulinum
salmonella
vector borne diseases
bacterial (lyme/tick)
arthropod borne (arboviral via mosquito)
parasitic (malaria via mosquito)
more common in summer because more people outdoors
vaccine preventable diseases
conditions that can be prevented by immunization
diptheria
tetanus
whooping cough (pertussis)
hepA&B
deaths from vaccine preventable diseases worldwide
pneumoccocal largest percentage (28%)
measles 2nd (21%)
rotavirus (18%)
zoonotic diseases
diseases transmitted from vertebrae animals to human beings
rabies, anthrax, avian flu(bird flu)
hantavirus
toxoplasmosis
tularemia (rabbit fever)
emerging infectious diseases
newly appeared in a population or has been known for some time but is rapidly increasing in incidence or geographic range
west nile, dengue, sars, mrsa, zika
bioterrorism related disease
deliberate release of viruses, bacteria, or other germs/agents to cause illness or death in people, animals, or plants
Level A agents: anthrax, smallpox, botulism, plague, tularemia, ebola
methods of outbreak investigation
clinical observation
epidemic curve
incubation period
attack rate
case mapping
hypothesis formulation and confirmation
draw conclusions
clinical observations
pattern of symptoms suggests possible infectious agents
possible symptoms of outbreak are:
fever
nausea
diarrhea
vomiting
headache
rashes
stomach pain
epidemic curve
a graphic plotting of the distribution of cases by time of onset
may reflect a common source epidemic or point source epidemic
common source epidemic
people are exposed continuously or intermittently to a common harmful source. the period of exposure may be brief or long. a continuous exposure will often cause cases to rise gradually (and possibly plateau rather than peak)
*spread over multiple days
point source epidemic
when the exposure is brief and essentially simultaneous the resultant cases all develop within one incubation period of the disease
incubation period pt 2
in conjunction with information about symptoms provides clues to possible infectious disease agents
attack rate
used to describe the occurrence of foodborne illness, infectious diseases, and other acute epidemics
secondary attack rate
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