Transcript Micro-Lecture-DOF-FEB-2006-v0-3

Control of infection in the
community
Darina O’Flanagan
Director
Health Protection Surveillance Centre
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
• Legionnaire’s Disease
• Responding to Emerging Diseases: Pandemic Influenza
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.”
Risk Assessment vs. Risk
Management
Risk monitoring
Monitor information
Epidemic intelligence
Assess signal
Risk assessment
Investigate PH alert
Risk management
Risk communication
Implement control measures
Disseminate information
Epidemic Intelligence Framework
Important for new International Health
Regulations
Event-based component
Event monitoring
Indicator-based component
Report
Data
Capture
Filter
Verify
“Surveillance” systems
Collect
Analyse
Interpret
Signal
EWRS
Rapid inquiries
Public health Disseminate E-Alerts
IHR
Alert
Investigate
Epi bulletin
WEB
Assess
Control measures
Epidemic Intelligence
Definition
« 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. »
Indicator-based EI component
Healthcare settings
• Identified risks
– Mandatory notification
– Laboratory surveillance
• Emerging risks
– Syndromic surveillance
– Mortality monitoring
– Health care activity
monitoring
– Prescription monitoring
– Poison centres
Risk monitoring
Event-based surveillance
• Domestic
– Media monitoring
– EI focal points
• International
– Information scanning tools (GPhin, MedISys)
– Distribution lists/Networks
• PROMED
• WHO-OVL
– International agencies
Event-based surveillance
Info scanning tools - GPhin
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
National Disease Surveillance Centre
“Unusual clusters or changing
patterns of illness” (Outbreak)
A cluster (outbreak) of infection or food-borne illness
may be defined as two or more linked cases of the
same illness or the situation where the observed
number of cases exceeds the expected number.
Clusters (outbreaks) may be confined to some of the
members of one family or may be more widespread
and involve cases either locally, nationally or
internationally.
Notifiers are also required to notify changing patterns
of illness that may be of public health concern,
including those that may indicate a bioterrorist related
outbreak.
10
Surveillance:
“you see what you
look at”
Report
Laboratory-based
surveillance
Pos. specimen
Clinical specimen
Seek medical attention
Disease
Infected
Exposed
Clinically-based
surveillance
Community-based surveillance
Serological survey
Acute Gastroenteritis Survey*
North 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
Invasive Meningococcal Disease
(IMD)
A highly succesful example of
primary prevention of
infectious disease in the
community
Jan
Feb
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Apr
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Aug
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Feb
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Aug
Sep
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Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Number of cases
IMD in Ireland 1999- 2004
Monthly number of cases
100
Oct 2000
90
Men C vaccine
80
70
60
Total
50
Group B
Group C
40
Other
30
20
10
0
1999
2000
2001
2002
Month/Year
2003
2004
Invasive Haemophilus influenzae type b
(Hib) disease
An example of surveillance data being
used to influence the childhood
immunisation schedule
D3
P3
Hib3
Polio3
MenC3
Quarter/Year
MMR1
Q3 2005
Q2 2005
Q1 2005
Q4 2004
Q3 2004
Q2 2004
Q1 2004
Q4 2003
Q3 2003
Q2 2003
Q1 2003
Q4 2002
Q3 2002
Q2 2002
Q1 2002
Q4 2001
Q3 2001
Q2 2001
Q1 2001
Q4 2000
Q3 2000
Q2 2000
Q1 2000
Q4 1999
Q3 1999
Q2 1999
Q1 1999
% Immunisation Uptake
Quarterly immunisation uptake rates
at 24 months in Ireland
95
90
85
80
75
70
65
60
Invasive Hib in Ireland 1987- 2005
120
Hib vaccine
102 104
95
80
76
80
68
60
IPV
42
DTaP
40
MenC
8
10
18
18
2005
7
14
2004
1998
7
2002
11
2001
10
2000
8
1997
7
1996
20
1999
23
Year
2003
1995
1994
1993
1992
1991
1990
1989
1988
0
1987
Number of Hib cases
100
Summary Hib in Ireland
• In 2005
– Incidence of invasive Hib disease increased in <5 yr olds
– Majority of Hib cases in <15 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 <4 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
Chemoprophylaxis
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 5001000 = 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.)
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
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
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
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
Chemoprophylaxis used
• Rifampicin
– Frequently used, oral (two days)
• Ciprofloxacin
– Becoming more frequently used (one dose)
• Ceftriaxone
– Often used for pregnant contacts
– IM injection
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 < 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)
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
TB
TB notification rates per 100,000 population, Europe, 2003
National Notifications of Tuberculosis
1952 - 2003
8000
7000
BCG introduced early
50s
Non-respiratory
Respiratory
6000
5000
4000
3000
2000
1000
Source: DoHC 1952-1997, HPSC 1998-2003
1992
1994
1996
1998
2000
2002
1952
1954
1956
1958
1960
1962
1964
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
0
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
25
20
15
10
5
Country
ia
d
R
om
an
la
n
Po
la
nd
I
Ire
N
E&
W
ro
at
ia
Fr
an
ce
D
en
m
ar
N
et
k
he
rla
nd
s
Sw
ed
en
Sc
ot
la
nd
C
ai
n
0
Sp
Rate per million
Incidence rate per million population of
legionnaires’ disease in various European
countries, 2004
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)
Case Legionnaires in Ireland
1999-2004
• 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.
– Male:female ratio is 2.2:1
– Age Range between 19-80 years and median age is
53 years
Diagnosis and follow up
• Notify MOH
• Check 14 day diary
• Notify EHO who will
sample water at hotels
+/- domestic houses
Emerging and re-emerging
zoonoses, 1996–2004
Ebola and CCHF
Influenza H5N1
Hantavirus
Lassa fever
Monkeypox
Nipah Hendra
vCJD
Rift Valley Fever
SARS-CoV
VEE
Yellow fever
West Nile
Brucellosis
Cryptospporidiosis
E Coli O157
Leptospirossis
Multidrug resistant Salmonella
Lyme Borreliosis
Plague
E P I D E M I C
A L E R T
A N D
R E S P O N S E
SARS in Ireland
• Notifiable since March 2003
• 50 cases investigated
• 17 cases in total identified (Case Definition)
– 1 Probable Case
– 16 Suspect Cases
– 60% male, Age Range: 1-77 years;
– Median: 45 years, Mean: 43 years
Distribution of cases
– ERHA (12); NWHB (2); SHB (1); MHB(1);WHBProbable Case (1)
• 8 with alternative diagnosis
–
–
–
–
Influenza A (2), Influenza B (1)
RSV (1), Acute Bacterial Pneumonia (2)
Exacerbation of COPD (1)
Atypical Pneumonia (1)-No organism isolated.
Influenza report available weekly at
www.hpsc.ie
Influenza A
Influenza B
ILI Rate
140
100
90
80
100
70
60
80
50
60
40
30
40
20
Number of positive specimens
ILI rate per 100,000 population
120
20
10
0
0
2000/2001
2001/2002
2002/2003
2003/2004
2004/2005
2005/2006
Season
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.
Why is there concern about avian
influenza A/H5N1?
• H5N1 has causes the largest outbreak in birds on
record, since late 2003
• Despite culling >150 million birds, its become
endemic in parts of SE Asia
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.
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 >50% of those
affected
– Most cases have occurred in
previously healthy children and
young adults
Cumulative Number of Confirmed Human Cases of Avian
Influenza A/(H5N1) Reported to WHO
13 February 2006
Country
2003
cases
2004
2005
2006
Total
deaths
cases deaths
cases deaths cases deaths cases deaths
Cambodia
0
0
0
0
4
4
0
0
4
4
China
0
0
0
0
8
5
4
3
12
8
Indonesia
0
0
0
0
17
11
8
7
25
18
Iraq
0
0
0
0
0
0
1
1
1
1
Thailand
0
0
17
12
5
2
0
0
22
14
Turkey
0
0
0
0
0
0
12
4
12
4
Viet Nam
3
3
29
20
61
19
0
0
93
42
Total
3
3
46
32
95
41
25
15
169
91
Total number of cases includes number of deaths.
WHO reports only laboratory-confirmed cases.
Controlling Spread?
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/
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
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-toperson
WHO alert phases
Inter-pandemic phase
New virus in animals,
no human cases
Pandemic alert
New virus causes
human cases
Pandemic
Low risk of human cases
1
Higher risk of human
cases
2
No or very limited human-tohuman transmission
3
Evidence of increased
human-to-human
transmission
4
Evidence of significant
human-to-human
transmission
Efficient and sustained
human-to-human
transmission
5
6
Four EU alert levels
Alert level
0
No cases anywhere in the world
1
Cases only outside the EU
2
New virus isolated in the EU
3
Outbreak(s) in the EU
4
Widespread activity across the EU
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
Minimum of
50,000
Minimum of 80,000
UK
Epidemic progression in Ireland
Number of people
1,400
1,200
1,000
800
600
400
200
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Week
Hospitalisations per week
Deaths per week
•Weighted sum of deaths over time from previous pandemics (1918,
1957, 1968) based on HPA UK planning model, Oct 2005
200 400
600 800 1000
Ro=1.8
Ro=1.39
Ro=1.28
Latent = 2 days
Infectious = 4 days
0
No. hospitalisations per week
1400
Hospitalisations per week
0
10
20
30
40
Weeks since first cases introduced
50
60
ffect of antivirals on hospitalisations per week, Ro=1.3
400
300
200
100
Latent = 2 days
Infectious = 4 days
0
Hospitalisations per week
500
AVT=0
AVT=5 per 100 pop
AVT>=12 per 100 pop
0
20
40
60
80
Weeks since first cases introduced
100
1000 1200 1400
400
600
800
AVT=0
AVT=10 per 100 pop
AVT=25 per 100 pop
AVT>=28 per 100 pop
200
Latent = 2 days
Infectious = 4 days
0
Hospitalisations per week
Effect of antivirals on hospitalisations per week,
Ro=1.8
0
10
20
30
40
50
60
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
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
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
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
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
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
•>65 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
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