Transcript PA-IN-Yr4 PH Paeds - Intro to Communicable Disease Control

Communicable Disease
Control
Public Health, Year 4, MMS
Yr 4 PH Paediatrics
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Why do Outbreaks occur?
• Groups of 3
• 5 minutes
• Rapid feedback
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PUBLIC HEALTH PEP
How do outbreaks occur?
•Need to have epidemiological
disease-cause triad of:
–agent
–host
–environment
•And a chain of transmission that
links the above
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The host-agent-environment triad
Host
Agent
Status: Susceptible/
Immune/ Infected
Response: No illness/
Typical illness/ Atypical or v
severe illness (e.g.
immunocompromised)
Infectivity
Pathogenicity
Virulence
conditions or influences not part
of agent or host, which influence
their interaction
Environment
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CHAIN OF
TRANSMISSION
The host-agent-environment triad
Host
Age
Genetic determinants
Nutritional status
Underlying medical condition
Immunosuppression
Co-infection
Treatment with antimicrobials
Behaviour
Psychogenic factors
Ability to survive in
environment
Mode of transmission
Ability to attach, invade,
multiply in host
Duration of infectivity
Evasion of host immunity
Resistance to
antimicrobial therapy
Immunity of immediate contacts
Incidence of infection in contacts
Human population density,
movement & mixing
Vector/ reservoir density
Disease incidence in vector/reservoir
Resistance to interventions in
vector/reservoir
Climate & environmental change
Antibiotics in the environment
Other pathogens
Water supply
Sanitation
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Agent
Environment
PUBLIC
HEALTHSecond
PEP edition. Edinburgh: Mosby; 2004
from Cohen J, Powderly. Infectious
Diseases,
PATHWAY
RECEPTORS
SOURCE
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Key terms
•Index case
• first case to come to the attention of the
investigator: not always the primary case
•Primary case
• case that introduces the disease into the
family/group/population
•Secondary case
• catches infection from primary case
•Incubation period
• time between between infection and developing
first symptoms
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Key terms 2
•Latent period= time between
infection and becoming infectious
• Incubation period= the time interval
between acquisition of infection and
onset of illness/symptoms
•Attack rate= proportion of exposed
population that becomes clinically ill
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SURVEILLANCE
Yr 4 PH Paediatrics
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What is disease surveillance?
systematic process of:
–Collecting and collating data
–Analysing data
–Interpreting the results
–feeding back the information to
those who need to take action
“INFORMATION FOR ACTION”
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It’s not new.....
•1660’s-1830’s: Bills
of Mortality weekly
statistics for numbers
buried in each parish
who died of the
plague & other
causes
•C19th: Medical
Since late C19th : statutory
Officer of Health
notification of infectious diseases
Reports
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Surveillance – a classical
model
Health care system
Event
Public Health Authority
Reporting
Real world –
Expect changes
Intervention
Data
Analysis and
interpretation
Decision
(feedback)
Information
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Surveillance vs. Research
Surveillance
•Applies existing knowledge to guide the health
system in the use of known control measures
- directly relevant to monitoring and control
measures
Research
•Pursues new knowledge from which better control
measures will results
- systematic investigation, testing and evaluation
designed to develop or contribute to knowledge
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Creating a Surveillance
system
• TASK: What do you do when you
are ill?
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Sources of data
Community
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Clinicians
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Health Protection Regulations
2010
• Requires :
• Registered medical practitioners to notify the proper
officer of the local authority if a patient:
• has a notifiable disease
• has an infection that could present significant harm
• is contaminated
• has died with a disease or infection that could present
significant harm
• Diagnostic laboratories to notify PHE when evidence of
infections caused by specified agents
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http://www.hpa.org.uk/Topics/InfectiousDiseases/InfectionsAZ/HealthProtectionRegulations
/
DISEASES NOTIFIABLE UNDER THE PUBLIC HEALTH
(INFECTIOUS DISEASES) REGULATIONS 2010
Acute encephalitis
Acute infectious hepatitis
Acute meningitis
Acute poliomyelitis
Anthrax
Botulism
Brucellosis
Cholera
Diphtheria
Enteric fever (typhoid or paratyphoid
fever)
Food poisoning
Haemolytic uraemic syndrome (HUS)
Infectious bloody diarrhoea
Invasive group A streptococcal disease
Legionnaires’ Disease
Leprosy
Malaria
Measles
Meningococcal septicaemia
Mumps
Plague
Rabies
Rubella
SARS
Scarlet fever
Smallpox
Tetanus
Tuberculosis
Typhus
Viral haemorrhagic fever (VHF)
Whooping cough
Yellow fever
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Laboratory
Yr 4 PH Paediatrics
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Patterns of reporting to national surveillance for Campylobacter,
Salmonella, norovirus and rotavirus, UK 2008–9.
Tam C C et al. Gut doi:10.1136/gut.2011.238386
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Copyright © BMJ Publishing Group Ltd & British Society of Gastroenterology. All rights reserved.
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Evaluating surveillance systems
Simplicity
Is system easy to access & use from perspective of various users
Flexibility
How readily can it be adapted
Data quality
Is data of sufficient quality & consistency to assure reliable use for intended purpose
Acceptability
Are procedures for obtaining data nonintrusive, are the data useful, perceived as wise
investment
Sensitivity
Probability that a case will be identified
What percentage of epidemics or outbreaks are detected
Predictive value
Probability of the disease/event given the surveillance data
Likelihood that alerts represent events that we are seeking to detect
Representativeness
To what extent is the pattern representative of the health of the population
Timeliness
Does system provide data that allows timely investigations & effective intervention
Stability
Is there assurance that trends reflect health/illness & not changes in how data
collected/managed
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Why is surveillance important?
1. Enables timely public health action for
sporadic cases e.g. contact tracing
2. Detection of outbreaks/clusters
3. Monitor trends in disease
4. Estimating magnitude of problem
5. Can monitor and evaluate prevention and
control programmes
6. Feeds into policy decisions and planning
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Success looks dull….
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MMHSC Study Day
OUTBREAK
INVESTIGATION
Recognising Outbreaks
Measles in a local authority area
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What is an outbreak?
An outbreak or an epidemic exists when
there are more cases of a particular
disease than expected in a given area, or
among a specific group of people over a
particular period of time
Or
One case of serious/rare disease e.g.
Ebola/plague/smallpox
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Why investigate outbreaks?
•To control it
•To understand what happened
•To prevent future outbreaks
•Research and training opportunities
•Programme evaluation
•Public, political or legal concerns
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Steps of an outbreak
investigation
1. Verify diagnosis
2. Confirm the outbreak
3. Define a case
4. Conduct case finding
5. Descriptive epidemiology
6. Formulate and test hypotheses
7. Analytical epidemiology
8. Microbiological and environmental
investigation
9. Implement and evaluate control measures
10.Communicate findings
These steps may occur simultaneously or be
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repeated as new information
is received
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INFECTION CONTROL
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HCAI
• Mandatory Surveillance
– Meticillin-resistant
Staphylococcus aureus
(MRSA) bacteraemia
– Meticillin-sensitive
Staphylococcus aureus
(MSSA) bacteraemia
– Escherichia coli (E. coli)
bacteraemia
– Clostridium difficile
infection (CDI)
• Emerging issues
– CPE
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– VRE
MMHSC Study Day
Infection Control Hierarchy
PPE
Administrative
Controls
Engineering Controls
Elimination of potential
exposures
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MMHSC Study Day
Your 5 moments for hand hygiene
Hand Hygiene- its not difficult
in the UK!
Yr 4 PH Paediatrics
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• And so to group work
Yr 4 PH Paediatrics
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