Control of Communicable Disease Flashcards
What are the categories of communicable diseases?
Parasitic, fungal, bacterial and viral
What are susceptible groups to infection?
Infants, elderly, those receiving medical treatment such as chemotherapy and those who are immunosuppressed
What are the lifestyle factors which increase infection risk?
Excessive alcohol consumption, poor nutritional status, People who inject drugs (PWID) which increases risk of hepatitis C.
What is a reservoir for infection?
Habitat where pathogen lives and multiplies such as the environment, humans or animals.
How does infection occur?
Pathogen seeks path to reservoir, path from reservoir, mode of transmission and path of entry to susceptible host.
What are the types of mode of transmissions?
Direct, indirect and airborne
What is direct transmission?
Skin to skin contact such as faceo-oral or sexual contact. Conditions include viral GI and STIs,
What is indirect transmission?
Includes both vector and vehicle borne transmission.
Vector-borne transmission is through a living organism such as mosquito for malaria.
Vehicle-borne transmission is through an inanimate object such as hepatitis B via cups or injections.
What is airborne transmission?
Respiratory such as TB.
What affects the transmission of communicable diseases?
Population density
Sanitation
Access to healthcare
Vaccination coverage
Deprivation which reduces preventative action
What is surveillance?
Collection, analysis and interpretation of information in order to take action
Why is surveillance important in control of communicable disease?
Identify clusters or outbreaks by measuring incidence of disease,
Monitor vaccine uptake and the side effects.
Monitor effectiveness of vaccine and outbreak control measures and antimicrobial resistance
What is passive surveillance?
Routinely collected data from health facillities by healthcare services such as lab reports which are generally incomplete are used to gain information about disease.
What is active surveillance?
Specifically collected data which includes blood markers that are used for Rare or contagious diseases
This is to achieve completeness.
What is sentinel surveillance?
Using select groups or institutions to gain a rough estimate of disease incidence from a limited sample.
What is enhanced surveillance?
A type of active surveillance which collects patient data using a range of sources such as detailed questionaires limited to a time/place/purpose.
What is syndromic surveillance?
Based on symptoms of patients in clinical settings rather than a diagnosis which can serve as an early warning system.
What are healthcare acquired infections?
Clostridium dificle, norovirus, MRSA, catheter associated UTI.
These can be from objects, staff, visitors or other patients.
Why do infections occur in healthcare settings?
High density setting
High number of immmunocompromised people
Invasive procedures such as catheters, ventilators and surgery exposes the body.
How can healthcare acquired infections be prevented?
Education
Screening
Isolation
Disinfection and decontamination
Learning from previous events through audits and root cause analyses
Hand hygeine.
What is an outbreak?
—>2 or more people with infection in a particular time/place.
—>There is a higher rate than expected of infection compared to the usual background rate.
—> A single case of infection of a rare disease.
What is the reproduction number?
Number of new individuals who will contract infection from a single person, in a population where all individuals are susceptible.
What is R0?
The reproduction number which is highly suscpetible to infection. It varies for different pathogens depending on innate infectiousness and the measures to limit transmission.
What is Re?
The reproduction number which has some level of immunity such as vaccination or isolation.
How can outbreaks be identified?
Lab reports
Clinical notifications
Increased demand for certain NHS products or services
Clinical notifications.
How can outbreaks be reduced from reservoirs?
Culling of birds/pings or using PPE when handling infected animals
How can outbreaks be reduced from mode of transmission?
Disinfection and decontaimination.
How can outbreaks be reduced from susceptible hosts?
Immunisation and adequate nutrition
What assumptions are made with R0?
There is no pre-existing immunity or previous exposure to the disease, therefore everyone is susceptible
No one has been vaccinated against the disease
Which factors affect the reproductive number?
Duration of infectiousness period
Likelihood of transmission occurring between infectious and susceptible person, which is greater in aerosol transmission
Average rate of contact between infectious and susceptible people
What is the disease with the greatest R0?
Measles has the greatest reproductive number, followed by chicken pox.
What is the order for disease R0?
Measles
Chickenpox
COVID-19
Ebola
Influenza
What are NOIDs?
Notifications of infectious disease, which includes:
Measles
Mumps
Yellow fever
Food poisoning
How are outbreaks managed?
Using surveillance to identify cases and confirm diagnosis, comparing to a baseline level for disease
Generating a hypotheses for the cause and testing it using analytical epidemiology
Determining a case definition
Communication to the public and organisations.
What is an epidemic?
A disease outbreak in a large number of hosts within a certain geographical area.
What is a pandemic?
Spread of disease across multiple areas.
What is a case definition?
The clinical criteria for a case to be considered as part of an outbreak, which depends on time and place and lab results.
How is an outbreak displayed graphically?
Epidemic curve, where cases on the y axis are plotted against time on the x axis. This can indicate the characteristic of the outbreak, divided into:
Point source outbreak
Propogate outbreak
What is a point source outbreak?
Occurs due to a single exposure period, which all cases occur in one incubation period like a meal or an event. This is characterised on an epidemic curve by a singular peak.
What is a propogated outbreak?
Outbreak has no common source and spreads from person to person, characterised on epidemic curve by separate peaks.
Which bodies are responsible for managing HAI’s?
Infection prevention and control team
Public Health England
Local authority
Staff
