Epidemiology Flashcards
What is epidemiology?
The study of the distribution and determinants of disease frequency in specified populations
Is the focus of epidemiology on populations or individuals?
Populations
What does frequency mean in terms of epidemiology?
The quantification of occurrence of disease
What does distribution mean in terms of epidemiology?
Who
When
Where
How
What are infectious diseases?
Those which are transmittable
- Measles
- Mumps
What are non-infectious diseases?
Those which are non-transmittable
- Heat disease
- Diabetes
What are contagious diseases?
Diseases which are easily transmitted by contact between hosts
- Flu
- Colds
What are non-contagious diseases?
Diseases whose spread usually requires a mode of transmission
- Lyme disease
What does reproduction number tell us about diseases?
How contagious and infectious the disease is
What is the reproduction number derived from?
The number of people who catch the disease from one sick person
What is reproduction number affected by?
The mode of transmission
The higher the reproduction number the ______ the herd immunity required.
Higher
What is incidence of disease?
The number of new cases of disease in a population at a particular time
What does the incidence of disease provide?
An indication of the risk of contracting a disease
What is prevalence of disease?
The total number of cases in a population at a particular time
- Existing and new cases
What does the prevalence of disease provide?
An indication of how common and widespread a disease is within a population
What is an epidemic?
An unusually high number of cases in a population at the same time
What is an outbreak?
An unusual cluster of cases appearing within a short time in a localised population
What is a pandemic?
A widespread epidemic
- Usually global
What is an endemic?
A disease which is constantly present in the population
What is sporadic disease?
Individual cases occur in geographically distinct places
- Not linked
What did John Snow identify?
Cholera outbreaks in London
What did Florence Nightingale record?
Statistics on typhus epidemic in English civilian and military populations
What did Ignaz Semmelweis discover?
Causes of deaths attributed to childbirth fever
Why are infectious diseases spread?
Global travel
Globalisation of food supply
Overcrowding
Closer contact with wilderness environments
What is chain infection?
Infection transported to the host via the route of transmission from a reservoir
Do all infected individuals exhibit disease?
No - carriers act as reservoirs for disease
Who was typhoid Mary?
An asymptomatic carrier of the agent that caused typhoid
What are the two modes of transmission by contact?
Direct and indirect
What is direct contact transmission?
Host to host
- Animal to person
- Person to person = mother to child, skin to skin, exchange of bodily fluids
What diseases are spread via direct contact transmission?
Rabies
STI’s
Measles
What is indirect contact transmission?
Via non-living objects = formites - Toothbrushes - Bedding - Drinking cups Via droplets in the air
What diseases are spread via indirect contact transmission?
Hepatitis B
Respiratory disease
What is indirect transmission?
Transmission by a medium
- Food and water
- Airborne
- Vector
What is indirect mechanical transmission?
Passive transmission of pathogens on the insects feet or other body parts
What is indirect biological transmission?
Active process through insect bite
What is infectivity?
The ease of transmission
What is pathogenicity?
The ability of a pathogen to cause disease
What is virulence?
How serious the disease outcome is
What measures may be taken to control disease?
Reduce pathogen reservoir
Reduce transmission of pathogens
Reduce host susceptibility to disease
How might pathogen reservoirs be reduced?
Human immunity
Animal immunity
Reduce vector population
How might transmission of pathogens be reduced?
Treatment of food and water to eliminate pathogens
Wearing masks = respiratory pathogens
How might host susceptibility to disease be reduced?
Immunity
What is active immunity?
Individual develops antibodies in response to infection or vaccination
What is passive immunity?
Individual gains antibodies via mother, injections of antitoxins or immune globulin
What is herd immunity?
The resistance of a group to infection due to the immunity of a high proportion of the members of the group
What pathogen causes small pox?
Orthopoxvirus
What is the reservoir for small pox?
Humans
How is small pox transmitted?
Respiratory route
