Define incubation period
Time between exposure to pathogen and presentation of symptoms
What is the aim of health protection?
Protect the public from communicable diseases and health risks associated with non-communicable environmental hazards
Name 4 agencies involved with control of communicable disease
Department of health
What is the epidemiological triad?
Model of the cause of infectious disease
Agent factors (microorganism)
Host factors (susceptibility, genetic, socioeconomic, lifestyle)
Environmental (climate, surroundings, services)
Where the agent lives, grows and multiplies. Can be human, animal or environment
What are the factors involved in a chain of infection?
Reservoir of agent
Portal of exit
Mode of transmission
Portal of entry
Susceptibility of the host
Name two direct modes of transmission of infection
Droplet (airborne, faecal-oral)
Name three indirect modes of transmission of infection
Vehicle: food, fomites, blood
Vector: biological, mechanical
Airborne: dust, aerosols
What are the key concepts in the control of infection?
Control the source
Protect susceptible individuals by immunisation or prophylactic antibiotics
Name three global health protection issues
Describe the factors that influence global health protection
Travel and migration: increase in international trade and migration affect incidence of certain disease e.g. TB, malaria, HIV, enteric fever more common in migrants. Human behaviour and lifestyle affects spread of disese e.g. STDs, Hepatitis
Change in environment and land use: acess to inaccessible land increases exposure to animals and insects carrying disease e.g. ebola, lassa fever
Climate change: affects vector breeding and insect/animal resovoirs/habitat.
Microbial adaption: antibiotic resistance
What is surveillance?
Continued monitoring of the occurence and spread of a disease
This is then interpreted and results are disseminated to relevant bodies so action can be taken.
What are the benefits of surveilance?
What is the purpose of surveillance?
Individual case management to prevent spread
Measures changes in incidence
Tracks changes in occurence and risk factors
Evaluate control measures
Provide information for emerging new infections of public health importance
Why do epidemics occur?
Increase in amount or virulence of an agent
Introduction of agent into a new setting
Enhanced mode of transmission
Increase in host susceptibility
Increase in host exposure
New portals of entry
How are outbreaks defined?
Two or more linked cases
Increase in background rate
Single case of rare or serious disease
Microbial or chemical contamination of food or water.
Why is it important to investigate outbreaks?
To reduce primary cases
Reduce secondary cases
Prevent similar outbreaks in future
What are the immediate control measures for an outbreak?
Controlling the source of infection
Protecting those at risk
How often a test is positive in a person who actually has the disese being tested
How often a test is negative in people who don't have the disease being tested
Positive predictive value
True positives/ true positives and false positives
Negative predictive value
True negatives/ true negatives and false negatives
What is descrptive epidemiology
Describes disease in context of time, person and place
Define latent period
Inactive period between exposure to an infection and subsequent illness
Describe the steps involved in the management of outbreak investigation
Detection: case reports, complaints, surveillane
Confirming the diagnosis: clincal /lab diagnosis. Quantify extent of outbreak
Control measures: control the source, interrupt transmission, protect those at risk
Define infectious period
The period of time and infected individual is able to transmit a pathogen to a susceptible host