09-11-21 - Introduction to Health Protection Flashcards
Learning outcomes
- Understand principles of disease transmission
- Know the definition of sporadic, endemic, epidemic, pandemic
- Understand the concept of chain of infection
- Be able to describe the principles of control of communicable disease including definition of an outbreak
- Know your responsibility as medical practitioners to notify certain infectious diseases and disease states
What are the 5 different patterns of outcome occurrence?
1) Sporadic
• Occasional cases occurring irregularly
2) Endemic
• Persistent background levels of occurrence (low to moderate levels)
3) Outbreak
• Greater than excepted cases of endemic levels
• One case in a new area can be regarded as an outbreak
• Turns into epidemic if not controlled
4) Epidemic
• Occurrence in excess of expected level for a given period of time
• Disease spreads rapidly over large geographical areas
5) Pandemic
• Epidemic occurring in or spreading over more than 1 continent
What is the epidemiological triad?
What is each factor?
What are factors of each that facilitate the development disease?
How can they each be controlled to prevent the development of disease?
• The epidemiological triad is a triplet of factors that all contribute to disease
1) Host
• Potentially susceptible individual
- Facilitating factors:
- Age
- Genetic susceptibility
- Nutrition
- Immune status
- Control factors:
- Immunisation
- Prophylactic treatment (intended to prevent disease)
- Good nutrition and general health
2) Environment
• The external factors that affect the potential disease transmission
- Facilitating factors:
- Climate
- Sanitation
- Overcrowding
- Reservoirs of infection
- Control measures:
- Barriers e.g PPE, bed nets, condoms
- Hygiene measures e.g hand sanitation, reducing overcrowding, food safety
3) Agent
• The organism that causes the infection
- Facilitating factors:
- Virulence
- Infectiousness
- Infective dose
- Drug resistance
- Control measures:
- Treat cases
- Isolate cases
- Good prescribing practise (to prevent antibiotic resistance)
What are the 6 chains of infection?
1) Infectious agent
• The disease-causing organism e.g bacteria, virus etc
2) Reservoir
• Where the infectious agent usually lives and multiplies e.g humans, animals, insects, environment
3) Portal of exit
• The means by which the infectious agent leaves e.g saliva, nose, throat, vomit, faeces, blood
4) Mode of transmission
• How the infection moves to the susceptible host
• Airborne spread
• Sexual intercourse
• Skin to skin contact
• Vectors
• Direct transmission via droplet spread (coughing and sneezing)
5) Portal of entry • The place the infectious agent enters the new host • Mucous membrane of respiratory tract • Broken skin • Open wound • Urinary tract • Placenta
6) Susceptible host • The person who is at risk of infection • High risk groups • Elderly • Very young • Chronic disease • Immunosuppressed
How is each chain broken in the chain of infection?
1) Infectious agent
• Antimicrobial stewardship – coordinated program that promotes the use of antimicrobials
2) Reservoir
• Medical treatment of infected persons and asymptomatic carriers
• Insect or rodent eradication
• Animal welfare (e.g poultry vaccination)
• Environmental sanitation
• Clean water (e.g chlorination of drinking water)
• Pasteurisation of milk
3) Portal of exit • Covering mouth when sneezing • Face masks • Covering wounds • Condoms
4) Mode of transmission • Sterilization of surgical equipment • Airflow control in operating theatres • Handwashing • Cleaning of surfaces • Food safety practises • Safe sex advice
5) Portal of entry • Bed nets • Insect repellent • Protective clothing (e.g long trousers for ticks) • Surgical masks and gloves • Safe sharps disposal • Aseptic technique for canulation • Wound care • Catheter care
6) Susceptible host • Immunisation • Good nutrition • Recognise high risk patients • Treatment of underlying disease
What is the definition of an outbreak?
What are 8 steps for managing an outbreak?
- An outbreak is when the observed number of cases unaccountable exceeds the expected number for a given place and time
- Managing an outbreak:
1) Confirm it is an outbreak
2) Establish info on causative organism
3) Implement control measures
4) Identify source (and remove if possible)
5) Ensure all cases treated appropriately
6) Case finding
7) Surveillance
8) Learn lessons for the future
What do the following terms mean: • Basic reproduction number • Latent period • Incubation period • Infectious period
- Basic reproduction number (Ro) – used to measure the transmission potential of a disease
- It is the expected number of cases directly generated by one case in a population where everyone is susceptible
- Latent period – Period between exposure and infection
- Incubation period – Period between exposure and onset of clinical symptoms
- Infectious period - time period where a host is infectious, and can directly or indirectly transmit agents or pathogens to another susceptible host
What is the responsibility of healthcare professionals in terms of notifying in regards to disease?
What should they not do?
Who can be notified?
How soon should notification occur?
Why do we notify?
What are example of some notifiable diseases?
- All registered medical practitioners must notify their health board if they have a reasonable suspicion that a patient whom they are attending to has a notifiable disease
- They should not wait until laboratory conformation of the suspected disease before notification
• Who should be notified:
1) Consultant in Public Health (Scotland)
2) Proper Officer of the Local Authority (England)
• How to notify:
1) Electronically via SCI (Scottish care Information) gateway
2) Paper based option also available
- Notification should occur within 3 days of suspicion – but phone with urgent cases, and a follow up in writing
- We notify to give early warning to potential threats to human health
- This allows for assessment of what, if any, health protection action might be required to minimise the spread of such diseases and the subsequent risk to human health
