Epidemiology Flashcards
What is Epidemiology?
The study of the [], distribution, and [] of health and [] in a population…
- occurence
- determinantts
- disease
What is prevalence vs incidence?
-
Prevalence - of a disease is the total number of new and existing cases in a population in a given time
- Total number of people with a disease
- Can be expressed as percentage
- Incidence - of a disease is the number of new cases of the disease in a given period of time.
Are mobidity and Prevalence basically the same?
Yes
Morbidity…
- Is a [] condition
- [] - [] are the presence of two or more diseased [] within an individual
- Morbidity also used to describe the [] of a disease in a population
- diseased
- Co-morbidities, states
- rate
Mortality…
- measure of [] within a population due to any number of causes
- deaths
- not the same at morbidity.
Using the examples of the common cold and ebola - differntiate morbidity and mortality….
- Morbidity and Mortality do not go hand in hand.
- Common Cold - high morbidity but low mortality
- Ebola - low morbidity but high mortality
What is a diseases “progression” through stages in its host?
- Infection - organism invades host
- Incubation - no symptoms yet.
- Prodromal - mild symptoms
- Acute Phase - most sever signs and symptoms
- Decline - disease and symptoms are subsiding
- Convalescent Period - patent regains strength and returns to normal.
Which disease stage experience the most sever symptoms?
Prodromal or Period of decline?
- Pysche!
- Neither should - the acute phase experiences the most sever signs and symptoms
In which disease stage is the disease most likely gone from the host?
Decline or Convalescent
Convalescent
An Acute Infection can be a [] force. How?
- Selective Force
- As a population we do not have a good immune response/response yet…since it is the first time we experience it. So it is most likely to be deadly.
Do organisms that cause chronic infections lose or gain virulence?
- It depends.
- Most pathogens that are well adapted will become less and less virulent over time
- Chlamydia for example - doesnt really kill peeps.
- There are some exceptions though.
Since the parasite/virus/bacteria most likely needs the host to survive…[]-[] of host and parasite is common.
Co-evolution
A disease is [] if it is not usually presnt in a population and occurs infrequently
sporadic
An [] disease is constantly present in a populaiton, usually at low incidences.
endemic
A disease [] occurs when a number of cases of a disease are reported in a short period of time.
outbreak
A disease is an [] when it occurs in a large number of people in a population at the same time (usually spread out but still geographically contained)
epidemic
A disease [] is widespread, usually worldwide.
pandemic
Which disease transmission mechanism occurs in a small time frame and arrises from contamination of water or food?
- Common-source epidemics
- Cholera
What is the R0 number?
- The basic reproduction number
- number of cases predicted to arise from one single infected individual.
- Can only be gathered once disease is contained and well-tracked.
Which type of disease transmission mechanism shows a slow progressive rise and a gradual decline over a longer time frame?
- Host-to-Host epidemic
- Influenza and chicken pox
- Resistance of a group to infection due to immunity of a high proportion of the group = []?
- The [] [] number is the number of people in a population that need to be vaccinated in order to prevent the spread of a disease?
- Herd Immunity
- Herd Immunity Number
Diseases with high Ro numbers can be [] ?
A high Ro normally correlates to a [] Herd Immunity number?
- Cyclical
- Higher
- A [] host-to-host transmission - the infected individual transmits a disease directly to a susceptible host
- Without the assistance of an []
- Direct
- Intermediary
- Examples:
- Viral Flu, common cold, STD, ringworm
Transmission of a disease facilitated by an intermediary is a ….
Indirect host-to-host transmission.
What is a disease reservoir?
What are some examples of reservoirs?
- site in which infectious agent remain viable and from which infection of individuals can occur.
- Ex:
- Zoonosis - pathogens can be transmitted to humans from animals
- Vectorborne agents use insects/invertebrates as reservoirs
- Human carrier
- Anthrax can use soils (non-living reservoir)
- Giardia live in water (non-living reservoir)
What are 2 examples of non-living reservoirs?
- Giardia in water
- Anthrax in soils
What is a subclincal infection? What are people called who have a subclinical infection?
- Diseased individuals who show nor or mild symptoms.
- Carrier
What are 3 methods of control against a host?
- Surveillance - observation, recognition, and reporting of disease
- Quarantine - restricts movement of individual with active infection
- Travel Restrictions - lime likelihood through geographic isolation
What are controls directed against the “vehicle?
- Preventing contamination through water treatment and purification, proper sanitation procedures, food preparation guidelines
- “decontamination of wastes”
What are some controls against a “reservoir?”
- If reservoir is animal - immunize or destroy
- Insect habitats can be sprayed with insecticides
What controls can be directs against the pathogen?
- Immunization through vaccines
- Treatment through antivirals, antibiotics
- Less effective cuz spread not prevented
What is the difference between an emergent and re-emergent disease?
- Emergent - disease that suddenyl becomes prevalent
- Re-emergent - diseases that have become prevalent after having been under control
What are the 7 “common” ways a disease emerges in a population?
- Human demographics and behavior changing
- Technology and Industry
- Economic development and land use
- International travel and commmerce
- Pathogen adaption
- Breakdown of public health
- Unusual events that upset host-pathogen balance
What characteristics should a biological agent possess?
- High transmission rate
- high mortality
- very stable, low rates of immunity
4.
What are the 3 ways anthrax can infect someone?
Which way is the most lethal?
- Cutaneous - non lethal
- Gastrointestinal - rare
- Pulmonary - deadly
