Control of infection in the community

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Control of infection in the community
Darina OFlanagan Director Health Protection
Surveillance Centre
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Learning objectives

• Importance of Surveillance/ Epidemic Intelligence
• New International Health Regulations
• Clusters of unusual diseases
• Iceberg concept
• Importance of reporting culture
• Primary prevention of infection in the community
  Vaccination
• Secondary Prevention
• Chemoprophylaxis
• Haemophilus influenzae meningitis
• Invasive Meningococcal disease, Invasive Group A
  Strep, TB
• Outbreak Management in the Community
• Foodborne Outbreaks done with Dr McNamara
• Legionnaires Disease
• Responding to Emerging Diseases Pandemic
  Influenza

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Definition of public health surveillance

• The ongoing systematic collection and analysis
  of data and the provision of information which
  leads to action being taken to prevent and
  control a disease, usually one of an infectious
  nature.

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Risk Assessment vs. Risk Management
Monitor information
Risk monitoring
Assess signal
Risk assessment
Investigate PH alert
Implement control measures
Risk management
Disseminate information
Risk communication
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Epidemic Intelligence Framework Important for new
International Health Regulations
Event-based component
Indicator-based component
Event monitoring
Surveillance systems
Report
Data
CaptureFilterVerify
CollectAnalyseInterpret
Signal
EWRS Rapid inquiries E-Alerts IHR Epi bulletin WEB
Assess
Disseminate
Public health Alert
Investigate
Control measures
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Epidemic IntelligenceDefinition

• Epidemic intelligence is the process to
  detect, verify, analyze, assess and investigate
  signals that may represent a threat to public
  health. It encompasses all activities related to
  early warning surveillance functions but also
  signal assessments and outbreak investigation.

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Indicator-based EI componentHealthcare settings

• Identified risks
• Mandatory notification
• Laboratory surveillance
• Emerging risks
• Syndromic surveillance
• Mortality monitoring
• Health care activity monitoring
• Prescription monitoring
• Poison centres

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Risk monitoringEvent-based surveillance

• Domestic
• Media monitoring
• EI focal points
• International
• Information scanning tools (GPhin, MedISys)
• Distribution lists/Networks
• PROMED
• WHO-OVL
• International agencies

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Event-based surveillanceInfo scanning tools -
GPhin
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Outbreak detection

• May 2000 Scotland
• Severe soft tissue abscesses systemic illness and
  death in IDU
• EU rapid alert issued
• Surveillance set up in A E
• Irish outbreak identified
• 22 cases, 8 deaths
• Clostridium novyii identifed
• New methadone clinics offered
• Messages to IDU not to muscle pop
• Attend early if any abscess

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Surveillance you see what you look at
Laboratory-based surveillance
Report
Pos. specimen
Clinical specimen
Clinically-based surveillance
Seek medical attention
Disease
Community-based surveillance
Infected
Serological survey
Exposed
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Acute Gastroenteritis SurveyNorth and South

• Frequency of IID 4.5 per 4 week period
• 9000 new episodes per day
• 3.2M episodes per year
• Days of illness 12.6M per year
• GP Consultations 3000 per day (7.5 lab spec
  - 2 ill)
• 1.1M per year
• Working Days lost 1.5M per year
• Loss of Earnings 173M per year

Source FSPB. Acute Gastroenteritis in Ireland,
North and South, FSPB, Dublin 2003
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Invasive Meningococcal Disease(IMD)A highly
succesful example of primary prevention of
infectious disease in the community
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IMD in Ireland 1999- 2004Monthly number of cases
Oct 2000 Men C vaccine
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Invasive Haemophilus influenzae type b (Hib)
diseaseAn example of surveillance data being
used to influence the childhood immunisation
schedule
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Quarterly immunisation uptake rates at 24 months
in Ireland
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Invasive Hib in Ireland 1987- 2005
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Summary Hib in Ireland

• In 2005
• Incidence of invasive Hib disease increased in lt5
  yr olds
• Majority of Hib cases in lt15 yr olds occurred in
  vaccinated children 93
• Number of true vaccine failures increased
  dramatically in 2005
• 14 TVFs in 2005, 6 in 2004 (4/6 occurring in Q4)
  and 3 in 2003
• A selection of Hib vaccines associated with these
  failures
• 12/14 TVFs in 2005 occurred in children aged 13
  months 4 years
• Response to these trends
• National Immunisation Advisory Committee
  recommended that a catch up Hib dose be offered
  to children lt4 years of age, in order to further
  protect this age group from Hib disease.
• The catch up campaign was launched by HSE on 21
  November 2005
• HPSC continuing to closely monitor the situation
  through surveillance

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Chemoprophylaxis
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Chemoprophylaxis- Meningococcal

• Aim
• Eliminate carriage from network of close
  contacts
• Prevent further cases among susceptible close
  contacts
• Saliva inhibitory to meningococcal growth
• Secondary cases are rare
• less than 3 of all cases are considered
  secondary cases.
• Risk of disease is highest amongst household
  contacts
• Highest risk in the 1st week, and falls over
  next 2-3 months. With chemoprophylaxis this is
  extended up to 6 months Attack rate x 500-1000
  1 households in 1st month (1 in 300 secondary
  contacts)
• Secondary cases in crèches etc v. rare, 4 cases
  over 3 years in population 56 million. (1 in 1500
  for crèche, 1 in 1800 for primary school and 1 in
  33000 for secondary school. A randomised control
  trial is impossible.)

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Chemoprophylaxis-Meningococcal

• For index patient
• as soon as can tolerate oral medication (unless
  treated with ceftriaxone if cefotaxime still
  need chemo)
• For close contacts
• If contact within 7 days prior to the onset
  (incubation 3-5 days) Eligible close contacts
  are
• household contact shared living/sleeping
  accommodation includes baby minders
• mouth kissing contact (usually close contact)
• Gave mouth to mouth resuscitation (1 in 100,000,
  wear masks!)
• in same nursery/crèche where nature/duration of
  contact is similar to to that for household
  contacts

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Chemoprophylaxis- School setting (1)

• School contacts
• Prophylaxis not indicated for sporadic cases, but
  give advice
• If 2 or more cases in the same class in the same
  term give to class members and teachers

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Chemoprophylaxis- School setting (2)

• in different classes management depends on
  factors such as
• interval between cases, size of the contact
  group, carriage rate in the school, whether due
  to vaccine preventable strain,
• incidence of the disease in the community ?
  community outbreak
• the degree of public concern

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Chemoprophylaxis

• Not recommended routinely on public transport
  e.g. bus and train
• Special consideration to party esp with
  pre-school children present - if decide to give
  give to all adults and children
• Special consideration to members of extended
  family where overcrowding or adverse living
  conditions
• Simultaneous administration is ideal but if
  someone missed then give up to within a month

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Chemoprophylaxis used

• Rifampicin
• Frequently used, oral (two days)
• Ciprofloxacin
• Becoming more frequently used (one dose)
• Ceftriaxone
• Often used for pregnant contacts
• IM injection

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Chemoprophylaxis - Hib disease

• Rifampicin recommended for 4 days
• 4 days needed to eradicate carriage (more days
  than for meningo) 20mg/kg/day (up to a max of
  600mg daily) once daily for four days
• Recent recommendations from UK recommend
  rifampicin to all household members if at risk
  individuals in household (regardless of
  immunisation status) i.e.
• Children lt 4 years in household
• Immunocompromised individual
• In crèche or playgroup
• Two or more cases in 120 day period, offer to all
  room contacts (children and adults)

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Invasive Group A Strep iGAS

• Most GAS infections mild such as strep throat or
  impetigo. Rare occasions can become invasive e.g.
  necrotising fasciitis or Streptococcal toxic
  shock syndrome
• Close contacts should receive chemo (oral
  penicillin) if symptoms suggestive of localised
  GAS infection
• Mother and baby if either develops iGAS in the
  neonatal period
• Other contacts should be given leaflet and warned
  to look out for symptoms for 30 days after
  diagnosis in the index case see leaflet on
  www.hpsc.ie

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TB
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TB notification rates per 100,000 population,
Europe, 2003
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National Notifications of Tuberculosis 1952 -
2003
BCG introduced early 50s
Source DoHC 1952-1997, HPSC 1998-2003
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What do we want to do? Stop people getting TB

• How?
• Find people with infectious TB as soon as
  possible and treat them
• Find their contacts and examine them to ensure
  that they have
• Not got TB
• Are not developing TB (TB infection / latent TB)
• Find people who have a high risk of having latent
  TB, test them and if positive for TB, treat them
  with chemoprophylaxis (new entrant screening)
• BCG

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Incidence rate per million population of
legionnaires disease in various European
countries, 2004
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Incidence of Legionnaires Disease

• Less than 5 of cases are notified through
  passive surveillance (Marston,1997)
• Legionella causes 2 to 16 of community acquired
  pneumonia cases in industrialised countries
  (Bohte,1995)
• Legionella causes 14 to 37 of severe cases of
  community acquired pneumonia, with associated
  mortality in excess of 25 (Hubbard,1993)

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Case Legionnaires in Ireland1999-2004

• Of 30 cases notified in this time period
• 11 were community acquired (36.8)
• 2 was nosocomial (6.6) (Laboratory confirmed
  case that occurs in a patient who was in hospital
  for all 10 days before onset of symptoms.)
• 17 were travel acquired (56.6) (A case who in
  the ten days before onset of illness stayed
  at/visited an accommodation site reported to
  EWGLI)
• Countries acquired included France, Ireland,
  Italy, Malta, Mexico, Portugal, Spain, Tunisia
  and USA.
• Malefemale ratio is 2.21
• Age Range between 19-80 years and median age is
  53 years

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Diagnosis and follow up

• Notify MOH
• Check 14 day diary
• Notify EHO who will sample water at hotels /-
  domestic houses

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SARS in Ireland
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Influenza report available weekly at www.hpsc.ie
ILI rate per 100,000 population and the number of
positive influenza specimens detected by the NVRL
during the 2000/2001, 2001/2002, 2002/2003,
2003/2004 2004/2005 seasons, summer 2005 and
the 2005/2006 season.
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Why is there concern about avian influenza A/H5N1?

• H5N1 has causes the largest outbreak in birds on
  record, since late 2003
• Despite culling gt150 million birds, its become
  endemic in parts of SE Asia

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Why is there concern about avian influenza A/H5N1?

• May mutate and start the next pandemic
• Domestic ducks can excrete large quantities of
  H5N1without signs of illness - silent reservoirs
• H5N1 viruses now more lethal to experimentally
  infected mice and to ferrets (a mammalian model)
• H5N1 has expanded its host range.
• The behaviour of the virus in its natural
  reservoir, wild waterfowl, may be changing.
• Spring 2005 die-off of circa 6,000 migratory
  birds at a nature reserve in central China, due
  to H5N1, was highly unusual and probably
  unprecedented.

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Why is there concern about avian influenza A/H5N1?

• When humans become ill with AI
• unusually aggressive clinical course with severe
  disseminated disease affecting multiple organs
  and systems
• Rapid deterioration
• High fatality
• It causes death in gt50 of those affected
• Most cases have occurred in previously healthy
  children and young adults

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Controlling Spread?
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Guidance re avian influenza at Phase 3

• Clinical assessment of people with ARI coming
  from country affected by H5N1
• Algorithm/guidelines for assessment
• Travel advice
• No travel restrictions
• Avoid wet markets, contact with poultry
• If ill on return contact GP
• General public concerns
• Seasonal flu vaccine for poultry workers
• If an outbreak of AI occurred in birds, exposed
  workers might be under public health surveillance
  and given oseltamivir prophylactically
• Details available at www.hpsc.ie/A-Z/Respiratory/
  AvianInfluenza/

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Lessons from past pandemics 

• Occur unpredictably, not always in winter
• Great variations in mortality, severity of
  illness and pattern of illness or age most
  severely affected
• Rapid surge in number of cases over brief period
  of time, often measured in weeks
• Tend to occur in waves - subsequent waves may be
  more or less severe
•     Key lesson unpredictability 
• Will also depend on the availability and
  effectiveness of antiviral drugs and vaccines

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Emergence of pandemic virus 3 requirements

• Novel virus subtype emerges, with little or no
  immunity in humans
• Virus can replicate in humans and cause serious
  illness
• Can be transmitted efficiently from
  person-to-person

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WHO alert phases
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Four EU alert levels

• Alert level
• 0 No cases anywhere in the world
• 1 Cases only outside the EU
• New virus isolated in the EU
• Outbreak(s) in the EU
• 4 Widespread activity across the EU

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Expected scale and severity
Expected excess deaths Expected excess hospitalisations
Global 2-50 million 6.4-28.1 million
Ireland 1- 5,000 3-14,000
UK Minimum of 50,000 Minimum of 80,000
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Epidemic progression in Ireland

• Weighted sum of deaths over time from previous
  pandemics (1918, 1957, 1968) based on HPA UK
  planning model, Oct 2005

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Hospitalisations per week
Latent 2 days Infectious 4 days
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Effect of antivirals on hospitalisations per
week, Ro1.39
Latent 2 days Infectious 4 days
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Effect of antivirals on hospitalisations per
week, Ro1.8
Latent 2 days Infectious 4 days
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Key components of pandemic flu preparedness and
response

• Surveillance and early diagnosis
• Antiviral drugs
• Vaccines (once they become available)
• Public health interventions
• Health system response and government response
• Communications

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Public health interventions

• Personal interventions
• Basic measures to reduce the spread of infection
• Hand washing prevents acquiring the virus from
  contact with infected surfaces and from passing
  it on
• Respiratory hygiene covering the mouth and nose
  when coughing or sneezing
• Avoiding crowds (where feasible) non attendance
  at large gatherings such as concerts, theatres,
  cinemas, sports arenas etc. nb STAY AT HOME IF
  YOU ARE SICK

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Possible population-wide interventions

• Travel restrictions
• Restrictions of mass public gatherings
• Schools closure
• Voluntary home isolation of cases
• Voluntary quarantine of contacts of known cases

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Antivirals

• Government has ordered stockpile sufficient to
  treat 25 of the population (including HCWs)
• Rationale
• 50 infection rate
• 50 of cases asymptomatic 25 clinical attack
  rate
• Enough to treat all who require it
• Plan is to treat, not to give prophylaxis
• Could lead to 50-77 reductions in
  hospitalisations and LRTI requiring
  hospitalization (Gani 2005)
• Initial shipment of 600,000 doses delivered.
  Balance due 2006.
• Logistics of rapid delivery being examined

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Vaccines 

• Routine seasonal flu vaccines will provide little
  or no protection
• The new virus strain has to be identified, and
  new vaccine must be developed to match the
  pandemic strain of virus
• Four to six months to produce, possibly longer
• Unlikely to be available during the early stages
• When available, aim to immunise whole population
  as soon as possible 2 dose schedule probable
• As production will take time, vaccines will be
  given to some groups before others according to
  nationally agreed priorities

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Vaccines

• Pandemic vaccine priority groups
• Providers of essential services (fire, utilities,
  etc)
• HC staff with patient contact
• High medical risk e.g. CHD, RF, DM, pregnant
  women (3rd trimester), children 6 months- 23
  months
• gt65 yrs
• Selected industries maintenance of essential
  supplies
• All age groups
• H5N1 vaccine
• Not matched to pandemic strain
• May provide some protection pending development
  of pandemic vaccine
• Enough to vaccinate 200,000 HCWs and essential
  staff

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Summary

• Opportunities for intervention depend on good
  surveillance data
• Unusual clusters are notifiable let us know!
• Guidance for control in new and emerging diseases
  evolve on practically a weekly basis check the
  web site www.hpsc.ie for latest updates