Theme 4- health improvement Flashcards
What is health protection?
“The protection of individuals, groups and populations through expert advice and effective collaboration to prevent and mitigate the impact of infectious disease, environmental, chemical and radiological threats”
What does PHE protect the public from?
- Chemicals and poisons
- Radiation
- Communicable disease
- And about emergency response – being prepared for major disasters
Why public health not under control?
- Societal events- war, migration, urban decay
- Human behaviour- travel, diet , recreation
- Health care- new devices, transplants, immunosuppresion
- Environmental changes- deforestation, flood, climate change
- Public health infrastructure- organisation, trained personnel
- Microbiological adaptation- antibiotic resistance, mutation
What is an outbreak?
Two or more associated cases- By definition, you need to find a link
A higher than expected incidence of cases- By definition, you need to know how many cases you expect
What is a hazard?
A hazard is a potential source of harm
A hazard in health protection terms is any substance or agent that poses a threat to health
What is the difference between a hazard and a risk?
Hazard is the potential to cause harm
Risk is the likelihood of harm
So in health protection we try to eliminate or mitigate the risks of harm from exposure to hazards
What are hazards categorised into?
- Radiation, chemical and environmental hazards
- Infectious agents that cause disease
Infectious agents fall into six groups what are they?
- Bacteria
- Viruses
- Protozoa
- Helminths
- Fungi
- Prions
What is the epidemiological triad of disease causation?
- Environment
- Host
- Agent
What are the agent factors?
- Infectivity
- Pathogenicity
- Virulence
- Minimal Infective Dose
What is infectivity?
Infectivity- The ability to enter and replicate in a host
What is patheogenicity?
Pathogenicity- The ability to cause disease in a host
What is virulence?
Virulence- The extent of disease an agent can cause in a host
What is the minimal infective dose?
Minimal Infective Dose- The amount of a pathogen that is required to establish an infection
What is opportunity of an infection influenced by?
Opportunity is influenced by level of exposure and host susceptibility
What are host factors?
- Genetics
- Age
- Lifestyle
- General health- better immune systems, co-morbidities lower the immune system and medication lead to pathogenic disease
- Nutritional status
- Psychological health- can increase exposure by taking risky behaviour, depression lowers the immune system
- Immune status
What are types of immunity?
- Innate immunity- The defensive system you were born with
- Adaptive/acquired immunity- Exposure to a pathogen triggers immune system to develop antibodies- natural or vaccine induced
- Passive immunity- Given antibodies rather than produced them oneself
What are environmental factors?
- Geography
- Climate
- Agriculture
- Infrastructure
- Social conditions
- Economic conditions
What is a communicable disease?
Communicable disease- An infectious disease transmissible by direct contact with an affected individual or the individuals discharges or by indirect means through a vector
E.g. Anthrax from exposure to a pathogen, not communicable as cannot be passed between humans
What is transmission?
Transmission- The process by which an infectious agent passes from an infected host to a susceptible host
What is transmissibility?
Transmissibility- The ability of an infectious agent to pass from an infected host to a susceptible host
What is the chain of infection?
Sequence by the infectious agent leaves its host or reservoir is conveyed by some mode of transmission and enters through an appropriate port of entry to infect the susceptible host
How do you control the communicable disease?
Controlling communicable disease requires breaking this chain of infection through interventions eliminate or reduce the infectious agent, prevent the infectious agent entering new susceptible hosts or reducing the susceptibility of potential hosts
What is a reservoir?
Reservoir- A location where an infectious agent can survive and multiply
What is a colonised reservoir?
Colonised (by bacteria)- bacteria surviving and multiplying (reservoir) but have not infected the host. Reservoir capable of being in chain of infection but are not affected at that point themselves
Human reservoirs- asymptomatic carrier?
Asymptomatic carriers- those infected but have not gone on to develop disease or those infected and incubating the disease but are not symptomatic
Human reservoir- symptomatic carrier?
Symptomatic carriers- shows symptoms
Human reservoir- convalescent carrier?
Convalescent carriers- those that have the disease and recovered but still have some infectious agent
Human resevoir- chronic carrier?
Chronic carriers- continue to harbour pathogen months and years after initial infection
Animal reservoir- zoonosis?
Zoonosis- An infection that is transmissible under natural conditions from vertebrate animals to humans
What is an environmental reservoir?
- Soil- can get cholera from soil and water
- Water
- Plants
What si mode of transmission?
how to get from reservoir to host
What is direct mode of transmission?
Direct- direct contact or droplet spread- requires physical proximity to the reservoir (kissing, sex)
Droplet spread classified as direct transmission- direct spread over a short range with large particles (sneezing, coughing etc.)
What is indirect mode of transmission?
- Airborne
- Vehicle borne
- Vector borne- mechanical and biological
Indirect transmission- transmitted to host without close proximity
What is airbone transmission?
Airborne is inhaled by host- infectious agents need to stay alive after leaving reservoir for some time.
What is vehicle transmission?
Vehicles- food, water, blood products and fomites (objects such as tissues, bedding, door handles, surgical instruments)
What is vector broen transmission?
Vector- any living organism that transfers and infectious agent from one host to another
What is a mechanical and biologiccal vector for mode of transmission?
- Mechanical vector (mosquitos, ticks)- land on food that someone ingests
- Biological vector- agent undergoes maturation in the intermediate host (mosquito in malaria)
What is latent period?
Latent period- The period of time between exposure to an infectious agent and the onset of the infectious period
What is incubation period?
Incubation period- The period of time between exposure to an infectious agent and the onset of clinical symptoms
What is infectious period?
Infectious period- The time period during which the infected person is able to transmit the infectious agent
What is an endemic?
A constant presence or usual prevalence of a disease within a geographic area
What is a cluster?
A group of cases in a defined place or time that are suspected to be greater than normally expected
What is an outbreak?
Two or more linked cases of a disease or more cases than would normally be expected in a given population
What is an epidemic?
More cases than would normally be expected in a given area, among a specific group of people over a particular period of time
What is a pandemic?
An epidemic that has spread to affect several countries over a large geographical region
How do outbreaks spread?
For infections transmitted from person to person, the crucial factor determining the spread of infection is:
How many secondary cases are caused by each infectious person?
What is Ro?
Basic reproduction number = Ro
Ro is the average number of secondary cases caused by a single infected case in a totally susceptible population
WHat is Ro = β x N x D?
- β = infectivity of organism
- N= contact rate
- D= duration of infectious period
What is the R number?
R is the average number of secondary infections produced by a typical infective agent in a homogenously mixing population where some of the population has immunity
What is the equation for R?
R = R0 x s
S = proportion susceptible
What is secondary attack rate?
- Secondary attack rate defines the spread of infectious disease in defined, small communities
- The proportion of those exposed to the index case that develop disease as a result of exposure
- It is context specific
What can we do for outbreak management?
- Epidemic preparedness
- Outbreak investigation
- Case definition
- Implement control measures
- Post outbreak evaluation
Essential factors in outbreak management
- Preparedness
- Proactive not reactive
- Community engagement
- Effective communication
WHO guidelines for communication of an outbreak
- Trust
- Announcing early
- Transparency
- Knowing your public
- Planning
Communicable disease control aims?
- control
- elimination
- eradication
What is control?
Control- The reduction of disease incidence, prevalence, mortality or morbidity to a locally acceptable level
What is elimination?
Reduction to zero of incidence of infection in a defined geographical area
What is eradication?
Permanent reduction to zero of the worldwide incidences of infection
What are measures of control?
- Surveillance
- Vaccination
- Strategies to prevent transmission
What is communicable disease surveillance?
“The continuous, systematic collection, analysis and interpretation of health-related data needed for the planning, implementation and evaluation of public health practice”
- Early warning system to detect outbreaks
- Monitor trends
- Evaluate interventions
What is a notifiable disease?
A notifiable disease is any disease that is required by law to be reported to government authorities.
Notifiable diseases are those deemed to have significant public health importance where the identification of potential outbreaks is essential.
When and how do you deal with notifiable diseases?
- Notification of clinical suspicion, accuracy of diagnosis is secondary
- Report any clinical suspicion
- Take appropriate swabs and blood for laboratory confirmation
- Treat as infectious until confirmed either way
- Supply completed notification form within 3 days
What is a vaccination?
- The process of administering a vaccine to a person or population with the aim of inducing immunity.
- Individual immunity for those vaccinated
- Herd immunity if immunization coverage is high enough
What is herd immunity?
When a sufficiently high proportion of the population is immune against a disease that the disease is unable to spread
What are the vaccination strategies?
- Routine immunization
- Mass vaccination campaigns
- Targeted immunization campaigns
- Travel vaccinations
Strategies to prevent transmission?
- Reducing the duration and level of infectiousness of cases
- Reducing the risk of transmission
- Reducing the contacts of infected people
Reducing the rate of transmission- how?
Health promotion
Physical barriers
- Condoms, nets, masks…etc.,
Ventilation
Vector control
Chemoprophylaxis
- Taking of medication to prevent infection (either before or after)
- Not suitable for long term risk reduction
- Drug resistance and side effects
Reducing contacts how?
- Social distancing
- Contact tracing
- Isolation
- Quarantine
Vaccine Hesitancy: 3Cs model
What are the C’s?
- Confidence
- Complacency
- Convenience
What does it mean confidence in terms of vaccine hesitancy?
Trust in
1) the effectiveness and safety of vaccines;
2) the system that delivers them, including the reliability and competence of the health services and health professionals
3) the motivations of the policy-makers who decide on the needed vaccines.
What does complacency in vaccine hesitantcy?
Complacency
Exists where perceived risks of vaccine-preventable diseases are low and vaccination is not deemed a necessary preventive action.
What does convenience mean in vaccine hesitancy?
Convenience
The extent to which physical availability, affordability and willingness-to-pay, geographical accessibility, ability to understand (language and health literacy) and appeal of immunization services affect uptake
Measures of control?
- Surveillance
- Vaccination
- Strategies to prevent transmission
Communicable disease surveillance?
“The continuous, systematic collection, analysis and interpretation of health-related data needed for the planning, implementation and evaluation of public health practice”
- Early warning system to detect outbreaks
- Monitor trends
- Evaluate interventions
What is a notifable disease?
Notifiable diseases are those deemed to have significant public health importance where the identification of potential outbreaks is essential.
What is vaccination?
The process of administering a vaccine to a person or population with the aim of inducing immunity.
- Individual immunity for those vaccinated
- Herd immunity if immunization coverage is high enough
What is herd immunity?
When a sufficiently high proportion of the population is immune against a disease that the disease is unable to spread
Vaccination strategies:
- Routine immunization
- Mass vaccination campaigns
- Targeted immunization campaigns
- Travel vaccinations
Strategies to prevent transmission
- Reducing the duration and level of infectiousness of cases
- Reducing the risk of transmission
- Reducing the contacts of infected people
Reducing the rate of transmission?
Health promotion
Physical barriers-Condoms, nets, masks…etc.,
Ventilation
Vector control
Chemoprophylaxis
- Taking of medication to prevent infection (either before or after)
- Not suitable for long term risk reduction
- Drug resistance and side effects
