Infection - Preventing Infections Flashcards
Give some examples of common sources that can infect more than one person
- food/water
- animals
- other environmental sources eg. plumbing systems can transmit Legionnaire’s
Give some examples of infections that are transmitted from person to person
Influenza, norovirus, neisseria gonorrhoea (many more)
How is malaria transmitted?
Person to mosquito to person, so through a vector
What is endemic disease?
The usual background rate of disease found in the environment
What is an ‘outbreak’ of disease?
Two or more cases linked in time and place
What is an ‘epidemic’ of a disease?
A rate of infection greater than the usual background rate
What is a ‘pandemic’ of an infection?
Very high rate of infection spreading across many regions, countries and continents. This becomes possible in cases of a virus undergoing antigenic shift
What is the basic reproduction number (R0)?
The average number of cases generated by one case over the course of its infectious period, in an otherwise uninfected, non-immune population
What does it mean if a disease has an R0 of 1?
There will be a stable number of cases
What does it mean if a disease has an R0 of more than 1?
There will be an increase in cases, eg. Measles has 12-18 so it will cause lots of cases
What does it mean if a disease has an R0 of less than one?
There will be a decrease in the number of cases
Give some reasons for outbreaks of disease
- new pathogen (new antigens, virulence factors or antibacterial resistance)
- new hosts
- new practice (social, healthcare)
What is the ‘infectious dose’?
The number of microorganisms required to cause infection. It varies by microorganism, presentation of microorganism and immunity of potential host.
Why is it possible to consume water contaminated with cholera but not get cholera?
A relatively large amount of cholera organisms is required to cause infection
What is an epidemic curve?
A bell-shaped curve which illustrates how the number of people infected changes over time - at first not many are infected, then lots are, then not many as most people have already been infected
What interventions can be made at the pathogenic level to prevent infection?
- reduce/eradicate pathogen using antibacterials, decontamination and sterilisation
- reduce/eradicate vector by eliminating breeding sites
What interventions can be made at a patient level to prevent infection?
- improved nutrition and medical treatment
- improved passive immunity (maternal antibody, IV immunoglobulin)
- improved active immunity (vaccination)
What is herd immunity?
A form of indirect protection from infectious disease that occurs when a large percentage of a population has become immune to an infection, thereby providing a measure of protection for individuals who are not immune
What interventions can be made in the environment to prevent infection?
Environmental engineering can help to provide:
- safe water
- safe air
- good quality housing
- well designed healthcare facilities
What practices can be adopted by healthcare professionals and the wider population to prevent spread of infection?
- avoid geographical area of pathogen/vector
- use protective clothing/equipment, eg. wearing long sleeves and trousers to protect against mosquito bites, or using gowns/gloves/marks in hospitals
- behavioural modifications, eg. practicing safe sex, safe disposal of sharps and food/drink preparation
Give some good consequences of control of infection
Decreased incidence/elimination of disease/organism, as in the cases of smallpox, polio and dracunculiasis
Give some bad consequences of infection control
- decreased exposure to pathogen can result in decreased immune stimulates and therefore less antibodies. This means there will be more susceptible individuals and there is a risk of outbreak occurring
- later average age of exposure leads to increased severity of illness
