Water and infectious diseases in EuropeWhat do we know?Gertjan Medema Water and Health, A European Perspective

Koblenz, 8-9 December 2009

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Water & disease in Europe: history?

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Water quality and health in Europe

Waterborne disease: Drinking water: pathogens are of greatest concern (Craun & Calderon, 2006)

Human water systems: pathogens are of greatest concernBathing water quality: pathogens are of greatest concern

Water & Health workshop• What is the size of the problem?

• How many Europeans are ill because of pathogens in their water?• What do we know?

• Why?• To understand burden of disease from water and relate this to other

(environmental) health impacts• To justify interventions / improvements in water systems

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Burden of disease estimates (WHO)

Burden of disease of water, sanitation and hygiene(Prüss et al, 2002)

• Infectious diarrhoea, (para)tyhoid, parasites• Water supply scenario’s• % Population in each scenario• Relative risk of illness based on intervention studies (preventable illness)• DALY’s (disease burden) & deaths

Europe8000 deaths / yr (0.4% of world)65300 DALYs / yr (0.9% of world)

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Burden of disease estimates (WHO Europe)Environmental factors (Valent et al 2004)

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Infectious disease surveillanceEuropean Centre for Disease Prevention and Control

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Infectious disease surveillanceFood and water-borne diseases and zoonoses

500 Million inhabitants:5497 cases

204104 cases17 cases (imported)6253 cases

Water + Food + Zoonoses

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Infectious disease surveillanceWaterborne pathogens: Cryptosporidium

Limitations of surveillance in current situation

• Data lacking from 11 countries

• Underreporting

• Assume EU = UK= 30000 cases / EU / yr= 471 DALY’s / EU / yr= 7.4 Million Euro / EU / yr(based on Van Lier & Havelaar, 2008)

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Infectious disease surveillanceWaterborne pathogens: Legionella

Assume France = EU= 10500 cases / EU / yr

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Infectious disease surveillanceThe reporting pyramid

CDC, Foodnet

Intestinal infectious diseasesWheeler et al, 1999 (England)

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1.4

6.2

17

136

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Infectious disease surveillanceFood and water-borne diseases and zoonoses

204104 cases7.6 community cases / reported case (Wheeler et al., 1999)

1.6 (0.7 – 3.6) million cases

Water + Food + Zoonoses

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Infectious disease surveillanceLegionella (NL)

SurveillanceCa 300 reported cases per yearHalf imported, half endemic

National Health Council 2003Surveys: ~5% of pneumonia in hospitalsis Legionella16000 pneumonia hospitalisations / yr800 Legionella hospitalisations / yr80 deaths / yr

If NL = EU: 24500 Legionella hospitalizations / yr

Legionellaoutbreak

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Infectious disease surveillanceWaterborne disease

Not specific to waterborne diseases (+ food + zoonoses)• Does provide picture for pathogens specific to water, such as

Legionella

Reporting pyramid: tip of the iceberg is visible• More information about the size of the iceberg from population

studies, translation to true incidence becomes possible

Surveillance systems efficiency differ between countries• Difficult to obtain Europe-wide information about incidence of

(waterborne) diseases

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WHO Europe 1986-1996: intestinal infections

2% of all reported intestinalinfections through tap water

55 outbreaks via drinking water with on average 220 cases (2-3500)

Microrisk: EU 1990-2004: 86 outbreaks through communitywater supply, 72546 cases, 341 hospitalizations, 1 fatal

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Community drinking waterborne outbreaks in Europe 1990-2004(Risebro et al, 2007)

Pathogen Isolated in Cases Bacterial Protozoal Viral

Water Supply

Country No. Outbreaks

Campylobacter Shigella Cryptosporidium Giardia Norovirus Viral

(undete-rmined)

Mixed Pathogen Gastroenteritis Ground-

water Surface Water Mixed Not

Reported

Finland 12 4 - - - 6 1 - 1 10 2 - - France 7 - - 2 - - - 3 2 5 - - 2 Germany 2 - - - 1 1 - - - 1 - - 1 Greece 3 - 2 - 1 - - - - 2 1 - - Italy 1 - - - - - - - 1 - - - 1 Netherlands 1 - - - - - - - 1 1 - - - Rep. Ireland 2 - - 1 - - - - 1 1 1 - - Spain 6 1 1 1 - - - - 3 1 - 1 4 Sweden 7 3 - - - 1 - 1 2 3 3 - 1 UK (England) 29 - - 28 - - - - 1 5 14 4 6 UK (N.Ireland) 3 - - 3 - - - - - - 3 - - UK (Scotland) 6 - - 5 - - - 1 - - 6 - - UK (Wales) 1 1 - - - - - - - - - - 1 UK (unspecified) 6 - - 6 - - - - - 3 2 1 - No. Outbreaks 86 9 3 46 2 8 1 5 12 32 32 6 16 Cases 72546 16222 531 7772 232 11408 2500 2511 31370* 43571 23047* 906 5022

= average of 5.7 outbreaks with 4836 cases / year

If EU = UK + Finland: 47 outbreaks with 40,000 cases / year

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Surveillance of waterborne outbreaks

Waterborne outbreak detection systems have a low recovery efficiency (Risebro et al, 2007)

• Need to improve case demographics of surveillance systems to facilitate outbreak detection

• Use of drug prescriptions, absenteeism, consultations are useful data to improve outbreak detection

• Link customer complaints of water consumers to health surveillance

Outbreak surveillance systems differ per country• Difficult to get Europe-wide picture

Information about cause(s) of the outbreaks • Allows prevention

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Household intervention studies GastroIntestinal (GI) illnessCommunity (surface) water supply

Colford et al, 2005 (USA)0%*UV and 1

µm filters

Coagulation, sedimentation, filtration, chlorination

Contaminated river

Colford et al, 2002 (USA)24%*UV and 1

µm filters

Coagulation, sedimentation, filtration, (ozonation), chlorination

Contaminated river

Hellard et al, 2001 (Australia)4%*UV and 1

µm filtersChlorinationProtected reservoir

Payment et al, 1997 (Canada)12%

Purified bottled water

Flocculation, filtration, ozonation, chlorination

Contaminated river

Payment et al, 1991 (Canada)34%Reverse

osmosisFlocculation, filtration, ozonation, chlorination

Contaminated river

SourceExcess risk of

drinking water

Interven-tion

TreatmentSource

Translation to USA:4.3 - 11.7 million cases of GI illness by community drinking water supply (Colford et al, 2006)

= 4 - 10% of all cases(Roy et al, 2006)

Incidences (/p/y)Waterborne GI: 0.023 – 0.064Total GI: 0.65

* No significant difference between study group with and without intervention

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Household intervention studies GastroIntestinal (GI) illnessCommunity (surface) water supply

No intervention studies in Europe

Direct translation USA = EU:12 - 32 million cases of GI illness by community drinking water supply

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Epidemiological studies

France: risk of childhood GI illness greater in alpine villages where the water did not satisfy drinking water standards (RR=1.7 95% CI 1.5 -1.9) (Zmirou et al, 1987)

France: correlation between drinking water turbidity and anti-diarrhoeal drug sales (Beaudeau et al, 1999)

UK: risk of GI illness is higher in case of pressure loss of tap water supply (Odds Ratio 12.5 (95% CI 3.5 – 45) (Hunter et al, 2005)

Norway distribution health epi study (Nygard et al, 2007)

• Consumers in area affected by repair had higher probability of intestinalillness (OR 1.6 - 2.0)

• Estimated # of GI cases 33000 on a population of 4.5 million• If Norway = EU: 3.7 million GI cases due to mains repairs

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Very small suppliesRisk assessment based on microbiological monitoring

E. coli monitoringFrance (CISEaux): 150775 samples of 4536 systems. 17.9% with E.coliEngland (UEA) : 34904 samples of 11233 systems. 18.9% with E. coli (Yip Richardson et al 2009)

Translate to risk of infection (Hunter, 2009)• step 1: use E. coli – pathogen ratio (Campylobacter, Giardia, Cryptosporidium)• step 2: use data on cold tap water consumption• step 3: use dose-response data of pathogens• step 4: compute risk of infection

Risk of infectionEngland 0.012/day; France 0.033/day. = 1 / yearNumber of EU citizens not connected to public supply: 34.3 millionPotential for multiple infections per year; potential for infection of visitors

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Risk of Cryptosporidium (Smeets et al, 2007)

Risk assessment based on statutory treated water data

If EU = UK surface water risk sites:13 million Cryptosporidium infections / yr

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Quantitative Microbial Risk Assessment

QMRA allows assessment of health risk in low exposure conditions

Translation of water quality data to health effects uncertain• Indirect relation (E. coli concentration)• Pathogen data: infectivity?

Case studies in several countries, difficult to translate to Europe-wide image

• QMRA valuable to identify water supply systems at risk in EU/country

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Burden of drinking waterborne disease in Europe (/ yr)

Burden of disease estimates (water, sanitation, hygiene)• 13,500 deaths, 550,000 DALY’s

Health surveillance• Total unknown (due to combination with food and zoonoses)• Typical waterborne pathogens:

• Cryptosporidium EU: 6253 reported, 30000 estimated• Legionella EU: 5497 reported, 10500 – 24500 estimated

Waterborne outbreaks• Reported: 5.7 outbreaks with 4836 GI cases • Estimated: 47 outbreaks with 40,000 GI cases

Epidemiological studies• Household intervention studies (US): 12 – 32 million GI cases• Distribution system repair study: 3.7 million GI cases

Quantitative Risk Assessment• Small supplies: 34.3 million infections• Cryptosporidium: 13 million infections

Different areasDifferent areas

Different outcomesDifferent outcomes

Different diseasesDifferent diseases

Different methodsDifferent methods

Different assumptionsDifferent assumptions

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Bathing waters

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Burden of disease estimatesEpidemiological + water quality data + exposure data

South California estimates (Dwight, 2005, Pendleton)

• Exposure data• 28 beaches • 90 million beach days per year• 28% swim in ocean

• Water quality data (enterococci)• Epi relation enterococci – GI risk

• Annual disease Cases Cost (USD)

• GI 0.6 – 1.5 million 21 – 49 million

Kay et al, 1994

Cabelli et al, 1982

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Epidemiological studies

Pond, 2005

Bartram, 2009

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Translate water quality data to health riskEngland & Wales (Georgiou & Langford, 2002)

Bathing waters (n=557)95.15 complied with EU mandatory level65.53 complied with guideline valueExposure data (survey 809 persons)

• 3.1 million exposures (swimming with head immersions)Water quality data (fecal streptococci) translated to excess risk of GI illness

• 0.065 per exposureExcess cases of GI illness due to swimming

• 1.96 million• Corrected for immunity: 1.75 million

If UK = EU: 16.5 million GI illness cases

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Health risk estimates based on water quality dataand epidemiology

Allows translation of water quality monitoring to burden of illness and cost of illness

• Conduct such studies!

Many water quality data available from statutory monitoring

Exposure data (beach visits, swimming and other water activities) limited

• EU surveys

Consistency of “dose-response” relation• Additional epi-studies (fresh water)• Validation studies

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Bathing water studies

Epibathe (marine and fresh waters)17 sites, 4 countries (UK, Ger, Hun, Sp), 7217 citizens

Wyn-Jones et al, 2009

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Bathing water studies

Epibathe marine waters

Wyn-Jones et al, 2009

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Bathing water studies

Epibathe fresh waters

Wyn-Jones et al, 2009

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Bathing water studies

Epibathe fresh waters, E. coli

Wyn-Jones et al, 2009

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Quantitative risk assessment

NLPathogen data in bathing waters (Cryptosporidium & Giardia)

• Crypto 4 – 200 / L; Giardia 1 – 53 / LExposure scenarios

• Incidental, occasional, frequentCalculated risk of infection

• Per swim event: 0.2 – 4.7%• Per year: 0.2 – 71%

Using data from UK: NL 9.3 million swim events with head immersion• 20,000 – 430,000 Crypto/Giardia infections per year

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Use of Quantitative Risk Assessment

Risk estimate based on water quality data• Pathogens (surveys needed)• E. coli / enterococci (US EPA, 2009)

Allows comparison of risk from different sources

Allows comparison of risk (or improvements) of different scenarios

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Conclusions?

Water and health in Europe, what do we know?• Mostly fragments• Burden of disease on European scale: rough

estimate• Drinking water

• Outbreak study on European scale: tip of iceberg• Drinking water disease burden is low

– Disease prevented by interventions• Areas of concern: outbreaks, very small supplies (both

esp. under climate change)• Water systems

• Legionella is still significant and water-specific health burden in Europe

• Bathing water• Epi + water quality: disease burden is significant (esp.

under climate change)

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Recommendations

Improve assessment of waterborne burden of disease in Europe• Disease prevented by good water practice

Improve outbreak surveillance

Improve small system surveillance

Improve Legionella surveillance

Determine bathing water associated burden of disease• European assessment based on available data• Validate with epi-study and QMRA

HEALTH

TARGETS

PUBLICHEALTHSTATUS

RiskManagement

Assessment of risk

AssessEnvironmental

Exposure

Acceptablerisk

From: Fewtrell & Bartram, 2001. in Water Quality Guidelines, Standards and Health (WHO). IWA publishing.