Transcript Public Health Medicine

Verotoxigenic E. coli in West
Limerick
Tessa Greally
Acting Director of Public Health, HSE MWA
on behalf of the Multidisciplinary Outbreak Control Team
June 2006
Verotoxigenic E. coli (VTEC)
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Commensal in cattle
Infection in humans first recognised in 1982
Commonest is E. coli O157 also O26, O111
MWA 8-10 cases per year
Ireland 86 cases in 2003, increasing numbers in
Ireland during 2005 (HPSC)
• Outbreaks
– Walkerton, Canada 2000, 2300 ill, 27 HUS, 7
deaths
– Scotland 1996, 17 HUS deaths
– Wales 2005, 1 death
Epidemiology
• Young and old most affected
• Transmission (V. low infective dose)
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Direct contact with animals
Animal faeces in environment
Person to person spread
Contamination of water, or food
• Incubation 1-8 days (usually 2-4 days)
• Need for microbiological clearance in “at-risk”
groups before return to work/school
VTEC O157 - transmission
•VTEC Outbreak,West Limerick, 2005
• Mid Western Area,
Ireland
•(pop 340,000)
•8-10 cases of VTEC
per year.
Outbreak Area/ West Limerick
• Small rural area –
cattle
• pop. 1500
• Commuters
• Private Group water
scheme (600 people)
• Boil water notice
• Recent Slurrying
• Heavy Rain
Wells vulnerability
Dept of Public Health, MWHA
October 2005
• 1 Acting DPH ( since 01/09/2005)
• DPH transferred to national A/ND post without
replacement
• I Acting SPHM
• 1 SpR
• 1 Senior Medical Officer( SMO)( on MPH leave)
• 1 Surveillance Scientist
• 1 Temporary SMO from Australia( covering MPH
leave for SMO)
• 3 Community AMOs not transferred
Split site
Index case- Tuesday Oct 25, 2005
Limerick PHU advised of a 2 year old child from
West Limerick with HUS in Temple St Hosp
• Recent history of diarrhoeal illness with negative
stool result at local hospital
• Risk factors
– Attended local un-notified creche
– Group Water Scheme serving creche under `”unfit”
notice
– Creche on a farm
Contact screening of faeces undertaken according
national guidelines
National screening guidelines
Microbiological screening of faeces of :
• All symptomatic close contacts
• All household contacts
• At risk groups-food handlers
• Health care
• Children < 5 years at nurseries, playgroups etc
• Older children and adults unable implement good
standards hygiene
Cluster 1
• Screening of creche, playgroup, junior infants
class at school (<5), families of cases.
• Index confirmed E.coli O157 VT2+ve
(VTEC)
• 8 contacts E.coli O157 VT2+ve, 4
symptomatic
– 1 childminder,
– 4 child-minding children<4 yrs,
– 3 family contacts of index (incl Sibling-a
schoolchild aged 4 years)
Cluster 2
• Child (10 yrs) from West Limerick attended A/E in Dublin
• with bloody diarrhoea but not admitted
• Public Health informed on November 2, 2005 in effort to
trace case
• Attended local school
• Confirmed E.coli O157 VT2+ve
• Only link mother had briefly looked after index case in
hospital, asymptomatic
• Mother negative
• Also lived on another GWS and had visited farm in Cork
recently with 2 wells
• Father subsequently developed bloody diarrhoea E.coli
O157 VT2+ve.
Cluster 3
• 2 yo from same area admitted bloody diarrhoea
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Developed HUS -Peritoneal Dialysis.
Public Health notified November 15, 2005
Attended another un-notified creche
6 contacts E.coli O157 VT2+ve (1 symptomatic)
– 3 child-minding children <4 years ( living on GWS1)
– 3 family contact s (father of child with HUS , 2 siblings of
child minding case)
• No contact with other 2 clusters
Epidemiological investigation
• Multi-disciplinary OCT convened 02/11/2005
• Case finding
– Local GPs, paediatricians, emergency department alerted
– Screening of 167 contacts including:
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2 Creches
1 Playgroup contacts
Families of those affected
School contacts (2 junior infant class)
• Trawling questionnaire on cases for VTEC exposures
– food, water, pets, travel, environmental (farms/cattle)
• Cases screened GP/Paediatric Unit for HUS
• Mapping of cases in relation to Group Water Scheme
• Case control study
‘Outbreak Curve’
Symptomatic
Asymptomatic
Case definition: Living in West Limerick, stool E Coli
0157 VT2 +ve phage type 32, from October 2005.
Cases mapped to Group Water Scheme
W=Well
R=Reservoir
Cluster 1
CASES
Cluster 2
Cluster 3
Group Water Scheme
Surrounding villages
E. coli 0157 cases by age group
No. of cases
14
12
10
8
6
4
2
6
6
1
0
0-4 y
5-9 y
10-14 y
15-34 y
1
1
1
1
1
35-44 y
45-54 y
55-64 y
Agegroup
Symptomatic
Asymptomatic
1st decision point – Friday October 28th
• Friday pm before Bank Holiday weekend
• Provisional positive results on 1 other child attending
creche and 2 grandparents
• Contacted
– childminder to advise that service should cease until negative
samples had been obtained from all children and the 2
childminders because of evidence of transmission within the
childminding situation families of remaining children to establish
whether samples had been sent and to advise that creche would
close
– paediatric unit to arrange clinical follow-up
– Childcare Unit to notify creche existence
– GPs
– EHOs- Co Council on standby for home water result
– Lab- further samples
– HPSC
2nd decision point Tuesday,
November 1st 2005
• 3 further provisional
positive results
reported – 4 year old
sibling at local
primary school and 2
further children in
creche
• OCT convened for
November 2nd
• Primary school
contacted during halfterm break to arrange
screening of junior
infant class using
school premises
3rd Decision point
• On confirmation on Monday pm of 2 further
provisional cases from Creche 2, both linked to
GWS1, decision to contact Group Water Scheme
trustees and Co. Council informed as a courtesy.
• Positive response from Co. Council who arranged
meeting for 8am 22/11/06
• Joint Boil Water notice distributed by Co. Council
on same day
• Grant provided by Co. Council towards
disinfection upgrading
th
4
Decision point
• Need to revisit descriptive epidemiology and
consider further studies to outrule other common
source of infection
• Staffing crisis because of staff exhaustion over
almost 4 weeks
• Agreement with PCCC Ass/ Nat Director to
second 3 AMOs to Public Health Dept and take
over Incident Room to accommodate staff.( Not
without protest!)
Case Control Study
• ? continous common source
• Hypotheses explored –childcare, water
consumption, travel, farm exposure to cattle, pets
and slurry, local meat suppliers, local food
suppliers, functions/events/eateries attended.
• Case definition: symptomatic case living in West
Limerick who had stools positive for E. coli
O157 VT2 + Phage type 32
• 3 controls per case, age group matched, same or
adjoining PHN areas randomly selected from
child databases
• 36 participants (9 symptomatic cases/27
controls)
Case control study results
Exposure
Case
Control
OR
P(fisher exact
test)
Total
Creche
9
7(2)
27
12(15)
4.4
.09
Pets
2(7)
16(11)
0.19
.06
Travel
3(6)
9(18)
1.0
.64
Farmland
6(3)
20(7)
.7
.49
Exposure GWS
6(3)
4(23)
11.5
.006
Drank GWS
3(6)
3(24)
4.0
.15
Unpasteurised Milk
1(8)
1(26)
3.2
.44
Home pasteurised milk 1(8)
8(19)
.28
.24
Other Investigations
• Environmental sampling
– Water samples-GWS, public supplies, private wells,
– 1 food sample
– Environmental inspections of schools, childcares,
playgroup
• Veterinary Investigation
– Animal faeces near wells
– Moores swab in water
– Animal samples taken from 5 herds from cases with
cattle and on farms adjacent to some wells on GWS
– Home pasteurised milk from farm where 3 family cases
Microbiology-Faeces
• >200 Faeces samples collected
–Samples cultured for VTEC using pre-enrichment
step
– VT, phage type,antibiogram, PFGE
– 167 contacts screened /152 contacts negative
– 18 cases of E.coli O157 VT2+ve phage type
32
– One cattle sample positive for E. coli O157
VT2+ve phage type 32
– PFGE for all positive human and veterinary
samples showed the same patterns
Microbiology-water
• 59 Water samples/1 ham sample
/home pasteurised milk
– No VTEC in food/milk sample or
water samples
– House of case- E Coli 1/100ml, 26
coliforms
– Raw water -E Coli 1/100 mls , 5
coliforms, 2 coliforms
Hydrogeology report on private
Group Water Scheme (GWS)
Vulnerable to contamination
• Agricultural catchment area
• Close contact wells/cattle
• Limestone-surface seepage into ground water
Problems with disinfection of 4 wells
• constant vs. variable chlorination,
• insufficient chlorine contact time,
• flow in both directions
• administrative
Control Measures
• Hygiene advice to cases and contacts
• “Voluntary” closure of two creches, junior infants
class(<5 years) and playgroup
• Exclusion of ‘at risk’ contacts/cases until
microbiological clearance
• Boil water notice on GWS( still in force!)
• Improved chlorination of GWS
• Education /monitoring/quality control of GWS
• Communications
– GPs, childcare centres
– Media
Potential Problem areas
• Consistency i.e. when to intervene and when to
withold intervention
• Staffing ( incl OOH)
• Accommodation
• Facilities – level 3 lab, fax etc
• Communication – Log of events, email, etc
• Relationships – PCCC ( difficult), Local
Authority ( good), GPs ( good), vets( good)
• Conflicting expert advice
Lessons
• Significant person-to-person spread in child-minding and
house-hold settings
• Multiple risk factors in rural/agricultural area
• Veterinary Perspective Need for a Programme of Routine
Surveillance
• Child care legislation - many child-minders are not notified
to HSE
• Poor public awareness re GWS
• Training needs of GWS trustees
• Need for category 3 containment level laboratory
• Use of multidisciplinary/multi-agency OCT
• Avoid Half term outbreaks!
Members of the OCT
Dr. Tessa Greally Chair
Mr. Denis Barron, Dr. Ann Carroll,
Dr. Carmel Collins,
Mr. Andy Curtin, Ms Annette
Fitzgerald
Dr. Rose Fitzgerald, Dr. Eleanor
McNamara,
Dr. Mai Mannix, Ms. Regina Monahan,
Dr. Tom Norris, Dr. Nuala O’Connell,
Dr. Fiona O’Dea, Dr. Mary O’Riordan,
Dr. Terry Prendiville, Dr. Joe Quinn,
Ms. Elaine Whelan, Mr. Dominic
Whyte,
Mr. Jim Buckley, Mr. John McCarthy,
Dr. Paul McKeown,
Other
Acknowledgements
Dr Tom Curtin
Dr. Patricia Garvey
Prof. Pat Wall
Dr. Meirion Evans
Dr. John Cowden
Mr. Dick McMahon
Mr. Tom Ward
Mr. PJ Kelleher
Mr. Cathal Ward
Public Health Laboratory, HSE, Dublin
Mid-Leinster
Limerick County Council