cryptosporidium monitoring of ireland's waters- theo de waal
TRANSCRIPT
Scoil Leighis Tréidliachta UCDUCD School of Veterinary Medicine
Cryptosporidium monitoring of Ireland's waters
Theo de Waal
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Outline
• Introduction
• What is Cryptosporidium
• How is it spread
• Cryptosporidium in humans
• Cryptosporidium in surface water
• National reference laboratory
• Survey of Irish water supplies
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Introduction
• Cryptosporidium first described in 1907 Tyzzer– C. muris
• Only associated with disease and death in 1955 in Turkeys– C. meleagridis
• In early 1970’s first reported of its association with diarrhoea in cattle
• In 1976 first two human case described – 3-year-old child– 39-year old immunosuppressed patient
• Today Cryptosporidium one of the most commonly identified intestinal pathogens 3
What is Cryptosporidium?
• Small single cell eukaryotic organism
• Found in GIT
• Oocyst environment– Small
• 4-8 µm in size– Smooth, thick outer wall– Contain infective sporozoites
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Cryptosporidium life cycle
• Direct life cycle
• Sporulated oocyst ingested
• Infect microvillus border of GIT – vertebrates– 3 species : Gastric mucosa– 1 specie: Respiratory system
• Complex development– Asexual multiplication– Sexual reproduction
• Autoinfection
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How is it spread?
• Transmission: faecal-oral route– Close contact– Waterborne– Foodborne
Fayer, R., 1997. Cryptosporidium and Cryptosporidiosis . CRC Press
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Cryptosporidium oocyst survival
• Very resistant!– Oocysts can remain viable in environment
& animal liquid waste ~ 1 year– Resistant to environmental stressors– Resistant to most chemical disinfectants
http://www.bio-uv.com/fr/site/Piscines-spas-collectifs/Prevention-Cryptosporidium/Prevention-contre-les-pathogenes-parasitaires_129_.html7
CRYPTOSPORIDIUM IN HUMANS
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Cryptosporidium spp:
• More than 22 recognised Cryptosporidium species– 39 Cryptosporidium genotypes
• Host specific - C. hominis to broad host range - C. parvum and C. ubiquitum
• Only few considered infectious to humans– Human cryptosporidiosis in Ireland1,2
• C. hominis (20%)• C. parvum (80%)
1. Zintl, et al, 2009, The prevalence of Cryptosporidium species and subtypes in human faecal samples in Ireland. Epidemiol. Infect. 137, 270-277.2. Graczyk, et al., 2007. Human enteropathogen load in activated sewage sludge and corresponding sewage sludge end products. Applied and Environmental
Microbiology 73 (6):2013-2015.
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Cryptosporidium in Ireland: Human
Year0
100
200
300
400
500
600
700
Cryptosporidium1
2004 2005 2006 20072008 2009 2010 2011
Nu
mb
er
cases
• Crude incidence rate– 6.9 – 13.4/100,000 annually
• Strong urban-rural divide
• Rural areas reported more cases
• Regional as high as– 31.4/100,000 per year
101Human cryptosporidiosis became a notifiable disease on January 1st 2004
Ireland: Seasonal distribution in humans
http://www.hpsc.ie/hpsc/A-Z/Gastroenteric/Cryptosporidiosis/Publications/EpidemiologyofCryptosporidiosisinIrelandAnnualReports/
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CRYPTOSPORIDIUM IN SURFACE WATER
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Cryptosporidium waterborne outbreaks
• First waterborne outbreak Braun Station, Texas (1984)
• Largest epidemic – Milwaukee, Wisconsin (1993)
• To date outbreaks affecting >106 individuals documented
Finnegan's Lake, County Galway.
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Cryptosporidium waterborne outbreaks - Ireland
Area Year Cases Source & Deficiency Species
Belfast 2000 & 2001 246 & 191 Septic tank seepage into reservoir C. bovine strain & C. human strain
Mullingar 2002 26 Heavy rain, agricultural runoff into lake. No filtration.
C. genotype 2 (=C. parvum) in humans
Ennis 2003, 2005, 2008 ? Surface water into spring source. No filtration
?
Carlow 2004 31 ? C. parvum, C. andersoni, C. muris in water. C. hominis in humans
Galway 2007 240 Agricultural runoff, sewage plant. Inadequate filtration
C. hominis and C. parvum in water and humans
Clonmel 2007 ? Surface water contamination following heavy rain
?
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Drinking water in Ireland- vulnerable?
• Surface water (82% of drinking water)• Climate
• High rainfall
• Geology – Shallow layer of soil and subsoil
over karst limestone – Heavy soils either rapid surface
runoff or preferential flow• Unprotected catchments
• Septic tanks• Livestock
• Inadequate treatment on some supplies
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Groundwater vulnerability map
Households with septic tanks
Cryptosporidium in Ireland: Environment
• Several Irish studies have detected Cryptosporidium species in Irish river basins1,2
• 2005 EPA risk assessment - Irish public water supply– 8% high risk– 13% very high risk
1. Graczyk, et al., 2004. Human waterborne parasites in zebra mussels (Dreissena polymorpha) from the Shannon River drainage area, Ireland. Para Research 93: 385-391.2. Lucy, et al., 2008..Biomonitoring of surface and coastal water for Cryptosporidium, Giardia and human virulent microsporidia using molluscan shellfish. Para Research 103:1369-1375
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Cryptosporidium in Irish Water
• Source of contamination and public health risk– Very limited information– No genotyping facilities in Ireland– Few local authorities get samples genotyped in UK
• Survey of Cryptosporidium monitoring in public water supplies– 24.5 % supplies being monitored
• >83% high Crypto risk score• Monitoring frequency low
Monitoring
catch
ment m
anag
emen
t
treatm
ent c
ontro
l
high
risk
scor
e
supp
ly on
RAL/n
o barr
ier
surfa
ce w
ater s
uppl
y
very
larg
e sup
ply
compl
iance
with
EPA
prog
ramme (
HSE)
unco
vered
rese
rvoi
r 0
10
20
30
40
Reasons given for routine monitoring
resp
onse
s (%
)
lack o
f res
ource
s
not r
equi
red by
legi
slatio
n
low ri
sk sc
ore
effec
tive t
reatm
ent
fed by
grou
ndwate
r 0
10
20
30
40
50
Reasons why supplies are not routinely moni-tored
resp
onse
s (%
)
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Development of a National Reference Facility for Cryptosporidium: 2010
• National survey of Irish public water supplies
• Adopt best practice procedures– Laboratory accreditation
• Pilot study of water supplies
• Significance of emerging waterborne contaminants
• Strategies for service delivery beyond project
National Reference Facility for Cryptosporidium
• Detection of Cryptosporidium in water– Based on USEPA 1622
• Filtration• Immuno-magnetic separation • Fluorescent antibody
• INAB Accreditation – ISO17025– April 2012
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Cryptosporidium Reference Laboratory
Genotyping • Source of contamination • Public health risk • Catchment protection• Water safety plan development for supply
• Frontline help in source contamination events or outbreak investigations without need for samples to be sent overseas
• Nurture and provide local knowledge and expertise
FITC stained Cryptosporidium oocysts
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Pilot Scheme - 2011
• Detection and identification of Cryptosporidium species in supplies on RAL
• 5 supplies selected
• “Type” supplies established– Groundwater under influence of surface water – Pristine upland lake – Spring/Borehole supply
Results to date
Pilot scheme details No samples %
Samples submitted 152
Positive USEPA 1622 74 48.6
Genotyped 46 62.2
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Type supply: Groundwater under influence of surface water
• No barrier for Cryptosporidium
• On boil water notice
• Previously had one sample genotyped in Scotland – very mixed results – up to 7 different species implicated
• No clear idea of source of contamination/ public health risk
Type Supply : Groundwater under influence of surface water
Date No of oocysts
detected
Oocysts/10 L Genotype Possible source Public Health Risk
March 156
0.190.3
C. andersoni Uncertain
April 64 0.45 C. parvum High
May 3 0.01 ND
June 2 <0.01 C. parvum High
July 3 0.01 ND
August 4 0.01 C. muris No risk
September 24 0.11 C. andersoni Uncertain
October 55 0.52 C. parvum/ C.ubiquitum
High
November 24 0.12 C. bovis/C.ubiquitum Uncertain
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Type Supply: Upland Lake
• Town supply - source water upland lake
• No barrier for Cryptosporidium• Cryptosporidium detected in 2007 during intense
monitoring period– C. parvum detected once in raw water– C. ubiquitum also detected once
• EPA audit conducted in 2009
Type supply: Upland lake monitoring results
Date No of oocysts
detected
Oocysts/10 L Genotype Possible source
Public Health Risk
March 3 0.02 ND
April 0 <0.01 N/A
May 16 0.14 C. ubiquitum Uncertain
June 52 0.33 C.ubiquitum/ C. xiaoi
Uncertain
August 1 <0.01 N/A
September 2 <0.01 no amplification
October 2 0.01 C. envir genotype ??? No known risk
November 3 0.01 C. envir genotype ??? No known risk
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Type supply: Spring/Borehole supply
• Spring & Borehole supply
• Spring supply located downstream of lake – concern over influence of lake over spring
• No barrier for Cryptosporidium
• July 2011 - 5 oocyts detected (0.02/10 L)
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Type supply: Spring/Borehole supply monitoring results
Date No of oocysts
detected
Oocysts/10 L Genotype Possible source
Public Health Risk
August 264 2.4 C. ubiquitum Uncertain
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SUMMARY
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Cryptosporidium spp. and genotypes in Irish Drinking Water Supplies
Cryptosporidium spp. detected No. Samples Possible source Public Health Risk *
C. andersoni 14 adult cattle/yearlings Uncertain risk
C. ubiquitum 11 deer/sheep Uncertain risk
C. parvum 4 preweaned calves/human High risk
C. bovis 4 weaned calves No known risk
C. environmental genotype 3 unknown No known risk
C. ryanae 1 weaned calves No known risk
C. muris 1 mouse Uncertain risk
C. andersoni / C. bovis mixed 1 calves/yearlings/adult cattle Uncertain risk
C. ubiquitum / C. xaoi mixed 1 wildlife/sheep Uncertain risk
C. andersoni / C. canis mixed 1 cattle/dog Uncertain risk
C. andersoni / C. muris mixed 1 cattle/mouse Uncertain risk
C. parvum / C. ubiquitum mixed 1 wildlife/cattle/sheep High risk
C. bovis / C.ubiquitum mixed 3 deer/sheep /cattle Uncertain risk
Total 46
As described in the UK Environment agency Microbiology of Drinking Water (2009)- Blue BookHigh risk: Known human pathogen and causative agent of outbreaks
Uncertain risk: Isolated from sporadic human cases but pathogenicity uncertainNo known risk: No human isolates reported
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Summary & Conclusions
• Drinking water in Ireland particularly vulnerable to Cryptosporidium contamination
• Risk of recreational waters?
• Humans incidence– Predominant spring peak
• C. parvum, C. hominis
• Cryptosporidium reference facility established in Ireland– INAB Accreditation – ISO17025
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Acknowledgements
– Carolyn Read– Jenny Pender– Annetta Zintl– Marzieh Mirhashemi
– Frances Lucy– Declan Feeney– Hui-Wen Cheng
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Original illustrations and photographs of Cryptosporidium parvum - Tyzzer, 1912