Surveillance of VTEC in Ireland

1. 1
Surveillance of VTEC
in Ireland
Dr Paul McKeown
Head GZV, HPSC

2. ID Regulations 2003 (SI 707) and 2011 (SI 452)
Disease Categories Lost
• Food poisoning
• Gastroenteritis in children
under 2 years
Disease Categories Gained
• Longer list of 16 diseases - IID
pathogens specifically listed
• Disease syndrome and Causative
Pathogen became notifiable
(Verocytotoxigenic E. coli
infection/ Verotoxin-producing E.
coli)
• Laboratory Directors become
notifiers (in addition to clinicians)
• Clusters/outbreaks become
notifiable
2
Immediate preliminary notification
VTEC is among 20 diseases/pathogens
for which there is a requirement by
clinicians/labs to notify to the MOH
immediately

3. VTEC Case Definition (1)
Clinical criteria
• VTEC : Diarrhoea and/or
Abdomincal pain and/or
HUS
• HUS: ARF AND
Microangiopathic
haemolytic anaemia and/or
Thrombocytopenia
Laboratory Criteria
VTEC: one of 3:
– E. coli strain producing
verotoxin OR vtx1 vtx2
– Direct detection of vtx1 or
vtx2 (w/o strain isolation)
– Free verotoxin in stool
HUS:
– E.coli serogroup-specific (LPS)
antibody response
• Overall culture is preferable
3

4. VTEC Case Definition (2)
Epidemiological criteria
• At least one of the
following:
- Human to human transmission
- Exposure to common source
Case classification
• A. Possible case: meeting clinical
criteria for HUS (except when
cause not VTEC)
• B. Probable case: meeting clinical
criteria for VTEC and with an epi
link OR lab confirmed case not
meeting the clinical criteria, e.g.
asymptomatic
• C. Confirmed case: Any person
meeting clinical and lab criteria
4

5. 5
158 167
226 241
199
283
554 702 707 730
740
3.7 3.9
5.3 5.7 4.7
6.2
12.1
15.3 15.4 15.9
15.9
19
32 31
27
22
36
1
10
100
1000
2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
VTEC Notifications/CIR/HUS - 2006-2016
Numbers
Rate/100,000
HUS
Data source: CIDR

6. 0
100
200
300
400
500
600
700
800
900
2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
Numberofnotifications
year of notification
Culture positive PCRpositive culture negative
Suspected VTEC (clinical HUS w/o Lab or Epi criteria) Epi-link (prob. only)
Serodiagnosis (HUS only)
Large Increase in VTEC Notifications since 2012
in Part Due to Changing Diagnostic Practice
Note: all specimens PCR positive for VTEC at local hospital are referred for culture to the Irish VTEC Reference Laboratory PHL Cherry
Orchard –the PCR positive culture negative notifications remaining in the figure are those PCR positive cases for which culture was
unsuccessful despite attempts at Ref Lab
Data source: CIDR

7. 0
100
200
300
400
500
600
700
800
2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
Numberofcases
Year of notification
Other
O145
O111
O103
O26
O157
Changing Serogroup Distribution among Culture
Confirmed VTEC Notifications, Ireland 2004-2016
Data source: CIDR

8. 0
10
20
30
40
50
60
70
80
90
100
0
50
100
150
200
250
300
350
0-4 5-9 10-14 15-19 20-24 25-34 35-44 45-54 55-64 65+
Rateper100,000population
Numberofnotifications
Age group (years)
number rate
Highest Age-specific Incidence Rates for VTEC
Reported in Children under 5 Years of Age
Data source: CIDR 2016

9. Strong urban rural divide in
VTEC incidence with the lowest
rates consistently reported in
HSE-East, which includes the
greater Dublin area
Crude incidence rate VTEC, Ireland 2016
Data source: CIDR
VTEC Incidence – Urban/Rural Divide

10. Consistent differences in seasonality between VTEC O157
and O26 in Ireland suggest underlying differences in
disease aetiology between the strains
Garvey et al Emerg Infect Dis. 2016
Apr;22(4):742-4
A: Raw data B: Modelled data
Data source: CIDR

11. 0
10
20
30
40
50
60
70
80
90
100
2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
Numberofoutbreaks
Year of notification
Person-to-person Waterborne +/- P-P
Foodborne +/- P-P Animal contact/environmental +/- P-P
Other Unknown/not specified
Person-to-person spread (within families and childcare facilities)
and waterborne spread from untreated or poorly treated private
water supplies are important VTEC transmission routes in Ireland
Data source: CIDR

12. The Future
• Refining Guidance
• Research – in particular, determining impact of asymptomatic carriage
• Emerging diagnostics (WGS) that will mean greater capacity to identify
clusters (but will we be any more equipped to identify the source?)
• Additional Pressures (Harvest 2020/Foodwise2025) –e.g. “Increase fertility
levels and decrease calving intervals in suckler herds”
• 2016: Total cattle population was 6,613,400 - 3% increase on 2015
• Improving the quality of private water supplies
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13. Take Home Messages
• Welcome surveillance capacity for HUS
• Not just O157
• Rising incidence – three aspects:
– Real increase
– Laboratory artefact
– Sensitive Surveillance System
• HUS notifications remaining pretty static but increase in 2016
means we need to remain vigilant
• Currently a very large burden (not least on the Public Health
System)
• We have to become more intelligent and selective in how we
manage this disease
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