Scoil Leighis Tréidliachta UCDUCD School of Veterinary Medicine

Cryptosporidium monitoring of Ireland's waters

Theo de Waal

1

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

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20

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Reasons given for routine monitoring

resp

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)

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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