125 terms

Epidemiology teslageiger

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STUDY
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what does epidemiology evaluate? (4)
Occurrence, determinants, distribution, and control of health and disease in a human population
what is infectious disease epidemiology concerned with?
agents or pathogens responsible for the spread of infectious disease
where is the center for disease and control and prevention?
US in Atlanta, GA
where is the World Health Organization?
Geneva, Switzerland
What is a sporadic disease?
A disease which occurs in single and scattered cases
what is an endemic disease?
A disease that is constantly present to a greater or lesser degree
what is an outbreak?
a sudden eruption of infections
What is an epidemic?
spreading rapidly and extensively by infection in an area or a population (global)
what is a pandemic?
epidemic over a wide geography and affecting a large portion of the population
what is an index case?
the case of the original patient that stimulates investigation; the first case of a contagious disease
morbidity rate
the number of new cases during a time period in a population
mortality rate
the number of deaths from disease in a population with the disease
prevalence rate
the number or people in a population who have a disease at a given time
(existing cases at a given time/total population)
what are surveillance methods of epidemiology? (9)
1. Morbidity and mortality data
2. case investigations
3. collection of data from reported epidemics
4. field investigation
5. review lab results
6. use of animal and vector disease data
7. information concerning biologics=antibiotics, vaccines, etc.
8. use data to watch movements of humans
9. Use geographic information systems (GPS) to follow disease
What are the periods of infection? (5)
1. Incubation periods
2. Prodromal period
3. Period of illness
4. Period of decline
5. Period of convalescence
What is the prodromal period?
The onset of signs/symptoms
what is convalescence period?
period of decline in which signs/symptoms disappear
when is a disease communicable?
incubation period-prodromal stage- ill
what are signs?
objective changes in body
what is an example of a sign
fever
rash
what are symptoms
subjective changes
what are examples of symptoms?
pain
loss of appetite
what is a disease syndrome?
set of signs/symptoms which characterize a disease
what are the two types of epidemics?
1. Common source epidemic
2. Propagated epidemic
what is an example of a common source epidemic?
food poisoning
Legionnaires' disease
What is Legionnaires' Disease?
severe pneumonia (Legionellosis)
what pathogen causes Legionarres' disease?
Legionella pneumophila
what is an example of propagated epidemic?
strep throat
what causes strep throat?
streptococcal pharyngitis
describe a common source epidemic
peaks within 1-2 weeks
which rapidly declines
Describe propagated epidemic
slow, prolonged rise with a gradual decline
what is herd immunity?
resistance of a population to infection and pathogen spread because a large portion of the population is immune due to vaccination or contraction
how does an infectious disease continue? (3)
1. infected humans give it to others
2. pathogen re-enters due to animal reservoirs
3. Pathogen evolves to continue its infectivity
what is an antigenic shift? (2)
1. Major genetic change
pathogen could no longer be recognized by immune system memory
2. Influenza changes by recombination with segments from other influenza when two different strains infects the same hose and trade segments
What is an antigenic drift?
Smaller antigenic changes occur with mutation in strains to help pathogen avoid immune system
what organism using coagulase?
staphylococcus aureus
what does coagulase do?
coagulates the fibrinogen in plasma
what do coagulates function to do for pathogen?
protects the pathogen from phagocytosis and isolates it from other host defense
what is pathogen uses collagenase?
clostridium spp.
what does collagenase do for pathogens?
breaks down collagen that forms the framework of connective tissues
-allows the pathogen to spread
what do porins do?
inhibits leukocyte phagocytosis by activating the adenylating cyclase system
what pathogens use porins? (2)
salmonella enterica
sevar typhimurium
what is the chain of infectiou disease order?
the pathogen- source of the pathogen- transmission to the host- susceptibility of the host- exist from the host
what is Koch's postulate 1?
1. the microogranism must be found in abundance in all organisms suffering from the disease, but not in healthy organisms
what is koch's postulate 2?
2. the microoganism must be isolated from a diseased organism and grown in pure culture
what is koch's postulate 3?
3. the cultured microoganism should cause disease when introduced into a healthy organism
what is koch's postulate 4?
the microorganism must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent
what are the four main routes pathogens are transmitted?
1. Airborne
2. Contact
3. Vehicle
4. Vector-Borne
describe airborne transmission?
Pathogen suspended in air, droplet nuclei
what are droplet nuclei?
small particles evaporated from large particles
describe contact transmission?
coming together or touching
what are the two kinds of contact?
direct and indirect contact
what is direct contact?
physical interaction (person to person)
what is indirect contact?
from pathogen to host through intermediate (cups, stethoscopes, neckties)
what is vehicle transmission?
inanimate objects throught fomties
what are fomites transmission?
any inanimate object or substance capable or carrying infectious organisms
what is vector born transmission?
either external or internal
What are examples of vector transmitters?
arthropods or vertebrates, flies
what are examples of airborne viruses? (4)
varicella, influenza, rubeola, rubella
what disease is caused by varicella?
chickenpox
what pathogen is responsible for measles
rubeola
what pathogen is responsible for german measles
rubella
what pathogen is responsible for smallpox?
variola
what pathogen is responsible with Pulmonary syndrome hantavirus
Hantavirus pulmonary syndrome
what are examples of airborne pathogens?(4)
actinomyces spp.
bordetella pertussis
chlamydia psittaci
corynebacterium diiptheriae
what pathogen can cause lung infections?
Actinomyces spp
what pathogen can cause whooping cough?
bordetella pertusis
What pathogen causes psittacosis?
chlamydia psittaci
what fungi are airborn pathogens?
blastomyces spp
coccidioides spp
histoplasma capsulatum
what pathogen fungi causes lung infections?
blastomyces spp
what fungal pathogen causes coccidioidomycosis
coccidioides spp
what fungal pathogen causes histoplasmosis?
histoplasma capsulatum
what disease are transmitted by arthropod vectors? (6)
malaria
african trypansomiasis
american trypansomiasis
yellow fever
dengue
ehrlichiosis
what causes malaria?
plasmodium spp
what causes yellow fever?
alphavirus (yellow fever virus)
what vector carries malaria?
anopheles (mosquito)
what vector carries yellow fever?
aedes
What pathogen causes dengue?
alphavirus (dengue fever virus)
what vector carries dengue?
A aegypti (mosquito)
what vector carries the plague?
xenopyslla cheopis (rat flea)
what are examples pathogen nonhuman reservoirs that may be transmitted to humans?
1. Anthrax
2. Babesiosis
3. Brucellosis
4. campylobacteriosis
5. Cowpox
how pathogen causes anthrax?
bacillus anthracis
what are the usual nonhuman hosts for anthrax?
1. cattle
2. horses
3. sheep
4. swine
5. goats
What is the method of anthrax infection?
inhalation or ingestion of spores; direct contact
what is the pathogen of babesiosis?
babesia bovis
what are the nonhuman hosts of babesiosis?
ixodes ticks
what is the method of infection for babesiosis?
bite of infected tick
what is brucellosis?
undulant fever
what is the pathogen of brucellosis?
brucella melitensis
what are the nonhuman hosts of brucelosis?
cattle
goats
swine
sheep
horses
what is the method of infection for brucellosis?
milk
is brucellosis indirect or direct?
either
what pathogen causes campylobacteriosis? (2)
campylobacter fetus
c. jejuni
what are nonhuman hosts for campylobacteriosis?
cattle
sheep
poultry
swine
pets
what is the method of infection for campylobacteriosis
contaminated water and food
what are zoonosis?
animal diseases that can be transmitted to humans
what pathogen causes giardiasis?
giardia intestinalis
what nonhuman hosts carries giardia intestinalis?
rodents
deer
cattle
dogs
cats
what is the method of human infection of giardiasis?
contaminated water
what is the the pathogen to Herpes B viral encephalitis?
herepesvirus simiae
what the method of infection in herpes b viral encephalitis?
monkey bite
contact with monkey materials
what host carries SARS?
bats
civit cats
what factors contribute to the hosts susceptibility to the pathogen? (5)
1. pathogenicity of infectious agent
2. host defense mechanism
3. host nutrition
4. genetic predispositions
5. stress
how does a pathogen leave the host? (4)
urine
feces
droplets
saliva
in order to continue infectious cycle, what does a pathogen need to do from a host?
successfully escape from the host
what are factors that enhance the spreading of disease around world? (11)
1. World wide population growth and shifts
2. Increased international travel
3. commerce, migration
4. microbial evolution and antibiotic resistance
5. changes in climate and ecology
6. modern medicine (immunosuppression)
7. inadequacy of public health and immunization
8. social unrest
9 virulence enhancing mechanisms of pathogens
10. changes in food processing, agriculture practices
11. changes in human behavior, technology, industry
what are three types of methods to control epidemics?
1. reduce or eliminate source/reservoir
2. break connection between source and potential host
3. Reduce number of susceptible persons and raise herd immunity
what are examples of reducing or eliminating source/reservoirs?(4)
1. quarantine and isolation of carriers
2.destroy animal reservoir
3. treat water sewage
4. reduce or eliminate infectivity with treatment?
what are examples of breaking connection between source and potential host? (3)
1. chlorinate water supplies
2. pasteurize milk
3. inspect food (destroy vectors)
what are examples of reducing numbers of susceptible persons and raise herd immunity?
1. passive immunization (temporary)
2. active immunization
what is active immunization?
the induction of immunity after exposure to an antigen
what is passive immunization?
transfer of active immunity (antibodies) from one individual to another.
what is an example of passive immunization?
antibodies passed from a mother to a child
what are nosocomial infections?
infections acquired during hospitalization
what are examples of hospital designated person responsible for identifying and controlling nosocomial infections?
hospital epidemiologists
infection control practitioner
what percentage of all hospital patients get nosocomial infections?
10%
what is an endogenous source regarding nosocomial diseases?
patient's own microbiota as a source
what is an exogenous source regarding nosocomial diseases?
microbiota other than patient's
what are examples of exogenous sources?
food
catheres
respiratory equipment
what should all hospital personnel follow?
isolation policies
aseptic technique
good surgical wound techniques
hand washing
gloving
what is the highest percentage of nosocomial diseases types?
urinary tract (34%)
what is the second highest in nosocomial infections?
surgical site infections (17%)
what is the normal microbiota found on the skin?
propionibacterium acnes
staphylococcus epidermis
staphylococcus aureus
corynebacterium xerosis
candida spp
what is the normal microbiota found in the eyes?
s epidermidis
s aureus
diptheroids
what is the normal microbiota found in the nose and throat
s aureus
s epidermis
aerobic diptheroids (nose)
streptococcus pneumoniae
haemophilus
neisseria