Cryptosporidium

Cryptosporidiosis is a disease caused by a microscopic protozoan parasites of the genus Cryptosporidium. It is primarily a food, animal contact and waterborne disease and although major outbreaks are thankfully fairly rare, the illness resulting from it can be serious and it is therefore important to try and stop it occurring wherever possible. The aim of these web pages is to provide background information on the disease, its occurrence and the control measures currently in place in the UK to deal with it.

Environmental health practitioners play a key role in monitoring and safeguarding the quality of water supplies in the UK and are instrumental in providing support and advice when an outbreak occurs. The body of knowledge about Cryptosporidium is growing fast and what we have been able to provide here is only a small part of it. We hope that you will find the pages in this section a useful introduction to the subject.


▼ Background Information 

Cryptosporidium is a protozoan parasite of the class Coccidia. Of two main types reflecting different seasonal peaks of infection, it is found world-wide and excreted in large numbers by a diverse variety of hosts including birds, fish and mammals and is able to live for long periods in animal droppings in fields, reservoirs and pipes. With a low infective dose - less than 10 organisms and possibly only one - it causes a self-limiting, but nonetheless very unpleasant gastrointestinal illness in humans, among whom two-thirds who contract the illness (Cryptosporidiosis) are children.  The elderly and otherwise immune-compromised are also at increased risk.

First identified in 1907, Cryptosporidium (`hidden spore`) is so named due to its very small (4-6 microns) size and the ease with which it can accordingly escape detection in samples. Detection methods have improved a lot since it was first found, but it is still a difficult and expensive process. 

Acting through the faecal-oral route (`bum to tum`), without a cure it has earned a worldwide reputation as a serious threat to public health. Although just as common as a food poisoning organism and one that can be acquired during farm visits, at petting zoos and from swimming pools, it is Cryptosporidium in drinking water supplies that has attracted the most attention as it is readily transmitted to large numbers of people in water and it is immune to conventional chlorination. Indeed, chlorination may actually increase the risk, as chlorine encourages the hard-coated oocyst to release the disease-causing sporozoites. Ultra violet light, ozone and membrane filtration are, however, effective against the organism. 

Often striking communities which had previously enjoyed safe water, in 1987, an outbreak of Cryptosporidium hit Carrollton, a university town in rural Georgia, USA, affecting 13,000 people out of a total population of 65,000 with diarrhoea, stomach cramps and vomiting.  In 1993, the City of Milwaukee, Wisconsin, suffered on an even bigger scale when an estimated 403,000 residents fell ill through contamination of the water system. Four thousand were hospitalised at an estimated cost of $54 million.  By 1992 reported cases of Cryptosporidium in the United States had reached the same level as those of Giardia, until then the most common protozoan contaminant in water. 

Cases in Europe also increased and since the first major outbreak, in Swindon in 1989, there have been over a dozen more reported in the United Kingdom, including from borehole supplies that had never failed any microbiological standards previously. The last major outbreak was traced to an infected rabbit that fell into a water storage tank.

Following the first series of major outbreaks, governments and their water suppliers had to find answers to many questions. In the UK, a series of official reports (firstly by Badenoch and then by Bouchier) provided a lot of useful information and tests have shown that source protection allied to attention to detail during treatment and not reusing backwash water are the best methods to reduce Cryptosporidium numbers in supply water. Where outbreaks do occur, boiling the water will inactivate the organism.

Though there is no known safe level for Cryptosporidium in treated water, it is nonetheless now rare in well maintained public water networks with multiple barrier treatment and robust detection systems in place and the greatest danger is to people who use private water supplies. These supplies are, of course, tested microbiologically for faecal organisms but, for reasons of cost and practicality, not routinely for Cryptosporidium. With little source protection and no, or inadequate, treatment systems in place and, often, a risk from the proximity of water sources to young stock animals, farm waste and septic tanks, the organism can be a serious problem for users of private supplies who might well be advised to connect to a public supply where available.

 
▼ Official UK information 

The Water Industry Act 1991

Under s.70 of this Act, it is an offence, subject to a "due diligence" defence, for a water undertaker to supply water unfit for human consumption.

The Private Water Supplies Regulations 2009 or 2007 in Scotland, 2010 in Wales and Northern Ireland)

These make it a duty on Local Authorities to serve notices where water is “unwholesome” or a potential health risk. Cryptosporidium in the water will cause the water to be both. Notices are described in Regulation 18 for unfit water and in Section 80 of the Water industry Act 1991 for unwholesomeness.

Local authorities also have a duty under the Regulations to monitor private water supplies (except owner-occupied single domestic properties) for contaminants. However the monitoring does not include Cryptosporidium specifically. Possible contaminants identified during a statutorily required risk assessment should be included in any monitoring as specified in the regulations and Cryptosporidium is often identified as likely to be present. Many would argue however that the faecal indicators that are specified in the regulations (including Clostridium) are likely to indicate the possible presence of Cryptosporidium and that Cryptosporidium is so unlikely to be found during random sampling and is so expensive to find that it is not routinely worth looking for.

Further information

 
▼ Previous UK outbreaks 

Bournemouth, May 2013

Greenmeadow Community Farm, Torfaen, Wales, April 2012

Investigation into an outbreak of Cryptosporidium infection in spring 2012

Merthyr Tydfil Leisure Centre, August 2009

Northampton, Pitsford Water Treatment Works - June 2008

Staffordshire, Oct – Dec 2007

North West Wales, 2005

  • Report of the Outbreak Control Team
    (Anglesey County Council, Anglesey Local Health Board, Centre for Research into Environment and Health, Dwr Cymru, Environment Agency Wales, Gwynedd County Council, Gwynedd Local Health Board, National Public Health Service for Wales)

Glasgow and Edinburgh, 2002

Northern Ireland, April 2001

Northern Ireland, August/September 2000

Cryptosporidiosis linked to swimming pools, Autumn 1999

Northumberland 1995 (Private Water Supply)

  • A mixed outbreak of Cryptosporidiosis and Campylobacter infection associated with a private water supply
    Reported in Epidemiology & Infection. Issue 116, pp 303-308. 1996

Torbay, South Devon 1992 and 1995

Cryptosporidium in Water Supplies. Report of the Group of Experts

Chairman: Sir John Badenoch. July 1990. HMSO. ISBN 0117523224.

Chapter 9. Outbreaks of Cryptosporidiosis.

 
▼ Outbreaks outside the UK 

2013

An Outbreak of Cryptosporidium at a Recreational Water Park in Niagara Region, Canada (Abstract )
Hopkins, J; Hague, H; Hudgin,G; Ross, L; Moore, D

  • Journal of Environmental Health. Vol 75, Number 9. May 2013

2012

Two geographically separated food-borne outbreaks in Sweden linked by an unusual Cryptosporidium parvum subtype, October 2010
Gherasim, M Lebbad, M Insulander, V Decraene, A Kling, M Hjertqvist, A Wallensten

Outbreak of Cryptosporidiosis associated with a man-made chlorinated lake? Tarrant County, Texas, 2008.

  • Journal of Environmental Health. Vol 75. No.4. November 201

2011

Outbreak of cryptosporidiosis in a child day-care centre in Gipuzkoa, Spain, October to December 2011

2008

A foodborne outbreak due to Cryptosporidium parvum in Helsinki, November 2008

A food-borne outbreak of cryptosporidiosis among guests and staff at a hotel restaurant in Stockholm county, Sweden, September 2008

2007

An outbreak of cryptosporidiosis at a day-care centre in Sweden

A large outbreak of cryptosporidiosis in western Ireland linked to public water supply

First reported waterborne outbreak of cryptosporidiosis with Cyclospora co-infection in Turkey

2005

Cryptosporidiosis outbreak associated with eating in a canteen, Denmark August 2005

2003

Cryptosporidiosis outbreak in British tourists who stayed at a hotel in Majorca, Spain

2002

Cryptosporidiosis outbreak in Ireland linked to public water supply May 2002
 

1996

An outbreak of cryptosporidiosis in the Netherlands

1994

A massive outbreak in Milwaukee of Cryptosporidium infection transmitted through the public water supply

 
▼ Cryptosporidium information held in the CIEH Library 

The following publications and journal articles are held in the CIEH library. The library, which is located at the CIEH headquarters in London is a specialist reference library dedicated to environmental health. It is open, by appointment, to all members of the CIEH and to those engaged in environmental health research. The opening hours are 9.00 am - 5.00 pm, Mondays to Fridays (excl. Bank Holidays.) If you would like to visit the library, please telephone 020 7928 6006.

Publications

  • Guidance for the investigation of Cryptosporidium linked to swimming pools
    Public Health Wales/Health Protection Agency. February 2011
  • Water Supplies: A Practical Guide
    David Clapham.
    SPON Press, 2004. 340 pp. ISBN 978-0-415-28282-6
  • Cryptosporidium in Water Supplies. Third Report of the Group of Experts
    Chairman: Ian Bouchier. November 1998. Department of Health/Department of the Environment. Published by TSO Ltd. . ISBN 1851121315
  • Cryptosporidium in Water Supplies. Report of the Group of Experts
    Chairman: Sir John Badenoch. July 1990. Department of Health / Department of the Environment. Published by HMSO. ISBN 0117523224.
  • Preventing Cryptosporidium getting into Public Drinking Water Supplies
    DETR consultation paper. May 1998.

Journal articles

2013 2012
  • Two geographically separated food-borne outbreaks in Sweden linked by an unusual Cryptosporidium parvum subtype, October 2010
    A. Gherasim, M Lebbad, M Insulander, V Decraene, A Kling, M Hjertqvist, A Wallensten
    Eurosurveillance, Volume 17, Issue 46, 15 November 2012  
  • Outbreak of Cryptosporidiosis associated with a man-made chlorinated lake? Tarrant County, Texas, 2008
    Journal of Environmental Health. Vol 75. No.4. November 2012
  • Outbreak of cryptosporidiosis in a child day-care centre in Gipuzkoa, Spain, October to December 2011
    Eurosurveillance. Vol. 17. Issue 5. 02 February 2012
     
2011
2010 2009
  • Long-term Cryptosporidium typing reveals the aetiology and species-specific epidemiology of human cryptosporidiosis in England and Wales, 2000 to 2003.
    R M Chalmers, K Elwin, A L Thomas, E C Guy, B Mason
    Eurosurveillance, Vol 14, Issue 2, 15 January 2009. pp 1-9
  • Epidemiology of human cryptosporidiosis in Ireland, 2004-2006: analysis of national notification data.
    Patricia Garvey, P McKeown
    Eurosurveillance, Vol 14, Issue 8, 26 February 2009
  • Compliance with boil water advice following a water contamination incident in the Netherlands in 2007
    I Karagiannis. B Schimmer, A M de Roda Husman
    Eurosurveillance, Volume 14, Issue 12, 26 March 2009
  • Prevalence of Giardia and Cryptosporidium in Muskrats in Northeastern Pennsylvania and New Jersey
    Adenike Bitto and Abdalla Aldras.

    Journal of Environmental Health (USA) Vol 71. No. 8. April 2009 pp20-26
  • A foodborne outbreak due to Cryptosporidium parvum in Helsinki, November 2008
    A Pönka , H Kotilainen, R Rimhanen-Finne, P Hokkanen, M L Hänninen, A Kaarna, T Meri, M Kuusi
    Eurosurveillance, Volume 14, Issue 28, 26 July 2009
  • Cryptosporidium rabbit genotype, a newly identified human pathogen.
    Chalmers RM, Robinson G, Elwin K, Hadfield SJ, Xiao L, Ryan U, et al.
    Emerging Infectious Disease. 15, 829-830. May 2009
     
2008
  • A swimming pool-associated outbreak of cryptosporidiosis in Staffordshire, England, October to December 2007.
    N Coetzee, O Edeghere, J M Orendi, R Chalmers, L Morgan
    Eurosurveillance.  Vol. 13. Issue 45. 6 November 2008. pp 1-3
  • Outbreak of Giardiasis and Crytosporidiosis associated with a neighbourhood interactive water fountain – Florida 2006.
    Leah Eisenstein, Dean Bodager, Dawn Ginzl.
    Journal of Environmental Health. Vol. 71. No.3. 2008 pp 18-22
  • Cryptosporidiosis Outbreak in a Nassau County, Florida, Return Travel Group from Ireland, May 24, 2006-June 4, 2006
    Rebecca Lazensky, Roberta M. Hammond, Kathleen Van Zile, Kim Geib
    Journal of Environmental Health. Vol. 71. No. 2. 2008 pp 20-24
  • A food-borne outbreak of cryptosporidiosis among guests and staff at a hotel restaurant in Stockholm county, Sweden, September 2008
    Eurosurveillance.  Vol. 13. Issue 51. 18 December 2008. pp 1-2
     
2007
  • Cryptosporidium parvum infection in orphan lambs on a farm open to the public.
    G. C Pritchard, J.A Marshall, M. Giles, R.M Chalmers, R. N Marshall
    The Veterinary Record. July 7, 2007. pp 11-14 

  • Cryptosporidiosis: A recreational water threat that hasn’t gone away
    Bruce T. Clark
    Journal of Environmental Health (USA)June 2007. pp 65-66 

  • Epidemiology of Cryptosporidiosis in rural Malawi
    T.D Mores, R.A.B Nichols, A.M Grimason & H.V Smith
    Environment and Health International. Congress edition. 2007 pp.36-44
     
2006
  • DWI considers crypto prosecution(reviews cryptosporidium incidents featured in the annual report for 2005 of the UK Drinking Water Inspectorate)
    ENDS Report.378. July 2006. p 21
  • Cryptosporidium outbreak linked to interactive water feature, UK: importance of guidelines
    M Jones, D Boccia, M Kealy, B Salkin, A Ferrero, G Nichols and J M Stuart

    Eurosurveillance Monthly. Vol. 11. Issue 4. April 2006 
  • Inactivation of Coccidian parasites by water purification chemicals and treatment device for campers and hikers
    M.B Lee and E.H Lee Environmental Health Review. Winter 2005. pp138-140 & p.148
     
2005
  • Outbreak of enteric cryptosporidiosis in cockatiels
    Y-K Kwon, S-H Wee, J-H Kook, C-G Lee Veterinary Record. Vol. 156. No.7. February 12, 2005. pp 210 - 211
  • Prevalence and characterisation of Cryptosporidium species in cattle faeces and on beef carcases at slaughter
    E. M Moriarty et al. Veterinary Record. Vol. 156. No.6. February 5, 2005. pp 165-168
  • Outbreak of enteric cryptosporidiosis in cockatiels
    Y-K Kwon, S-H Wee, J-H Kook, C-G Lee Veterinary Record. Vol. 156. No.7. February 12, 2005. pp 210 - 211
  • Identification of Cryptosporidium parvum genotype 2 in domestic horses
    R M Chalmers, A L Thomas, B A Butler , M C G Davies Morel. Veterinary Record. Vol. 156. No.2. January 8, 2005. pp 49-50
     
2004
  • Decontaminating swimming pools and managing cryptosporidium
    Brian Coll. Recreation. Vol 63. No. 4. May 2004
     
2003
  • The Elderly and Waterborne Cryptosporidium Infection: Gastroenteritis Hospitalizations before and during the 1993 Milwaukee Outbreak
    Elena N. Naumova, Andrey I. Egorov, Robert D. Morris, and Jeffrey K. Griffiths. Emerging Infectious Diseases. Vol. 9 No. 4 April 2003

  • Cost of Illness in the 1993 Waterborne Cryptosporidium Outbreak, Milwaukee, Wisconsin
    Phaedra S. Corso, Michael H. Kramer, Kathleen A. Blair, David G. Addiss, Jeffrey P. Davis, and Anne C. Haddix. Emerging Infectious Diseases. Vol. 9 No. 4 April 2003

  • Outbreak of Cryptosporidium in a public water supply in County Westmeath, Ireland
    Marie Gillooly. Environmental Health Scotland. Vol 15 (4). 2003. pp 10-15

  • Identification of Cryptosporidium parvum ‘cattle’ genotype from a severe outbreak of neonatal foal diarrhoea
    Veterinary Record. Vol. 153. No.20. November 15, 2003. pp 628-630
     
2002
  • Bench-marking Pool Water Treatment for coping with Cryptosporidium
    R Gregory. C.Eng, MIChemE, MCIWEM, WRc plc, Swindon. Journal of Environmental Health Research. Vol.1 Iss. 1 February 2002
    Bench-marking Pool Water Treatment for coping with Cryptosporidium 

  • Enhancing surveillance of cryptosporidiosis: test all faecal specimens from children
    P Crook, R Mayon-White, M Reacher Communicable Disease and Public Health. Vol 5. No. 2 June 2002 pp 112-113

  • Laboratory ascertainment of Cryptosporidium and local authority policies for investigating sporadic cases of cryptosporidiosis in two regions of the United Kingdom
    RM Chalmers, S Hughes, AL Thomas, S Woodhouse, PD Thomas, P Hunter Communicable Disease and Public Health. Vol 5. No. 2 June 2002 pp 114-118

  • Cryptosporidium Oocysts in a Water Supply Associated with a Cryptosporidiosis Outbreak
    Emerging Infectious Diseases. Vol 8. No. 6 pp 619-624. June 2002 Andrew D. Howe, Sue Forster, et al

  • Occurrence of Cryptosporidium in agricultural surface waters during an annual farming cycle in lowland UK
    AT Bodley-Tickell, SE Kitchen, AP Sturdee. Water Research 36 (2002) 1880-1886

  • Managing a large outbreak of cryptosporidiosis: how to investigate and when to decide to lift a 'boil water' notice
    SL Harrison, R Nelder, L Hayek, IF Mackenzie, DP Casemore, D Dance. Communicable Disease and Public Health. Vol 5. No. 3. September 2002. pp 230-239
  • Cryptosporidiosis in Malawi: Preliminary results of a study into the incidence of cryptosporidiosis in paediatric patients in rural and urban areas of Malawi
    T D Thomson, A M Grimason, K C Tembo, Z Banda, R Mwenda & R Chapepa. Environmental Health Scotland. Winter 2002
     
2001
  • Regulating Cryptosporidium - the first year
    ENDS Report 314. March 2001. pp 27-30

  • Possible undetected outbreaks of cryptosporidiosis in areas of the North West of England supplied by an unfiltered surface water source
    P Hunter, Q Syed, EN Naumova. Commun Dis Public Health 2001: 4; 136-138
     
2000
  • Effect of a boil water notice on behaviour in the management of a water contamination incident
    M O'Donnell, C Platt, R Aston. Communicable Disease and Public Health. Vol.3 No.1 March 2000. pp58-59

  • Advice on the response from public and environmental health to the detection of cryptosporidial oocysts in treated drinking water
    PR Hunter. Communicable Disease and Public Health. Vol.3 No.1 March 2000. pp24-27

  • Compliance with advice to boil drinking water during an outbreak of cryptosporidiosis
    LJ Willocks, F Sufi, R Wall, C Seng, AV Swan for the Outbreak Investigation Team Communicable Disease and Public Health. Vol. 3. No. 2. June 2000. pp137-138

  • Implications and importance of genotyping Cryptosporidium
    Rachel Chalmers, Kristen Elwin. Communicable Disease and Public Health. Vol.3. No.3. September 2000. pp 155-157
     
1999
  • Cryptosporidium: the experts give their opinion (about the Bouchier report)
    D Clapham. Environmental Health (EHJ). Volume 107. Issue 4. April 1999. pp114-115
     
1997
  • Outbreak of Cryptosporidiosis associated with a swimming pool in Andover.
    T Sundkvist, M Dryden, R Gabb, N Soltanpoor, D Casemore, J Stuart. Communicable Disease Report. Vol 7. Review No. 12. 14 November 1997. R190-R192
     
1998
  • Cryptosporidium and giardia lamblia in private water supplies
    David Clapham & Natasha Franklin. Environmental Health (EHJ). Volume 106. Issue 6. June 1998
  • Outbreak of waterborne giardiasis caused by sewage contamination of drinking water
    Peter M. Wallis, Brian Primrose & William J. Robertson. Environmental Health Review. Summer 1998. pp 44-51
  • Investigation of an outbreak of cryptosporidiosis associated with treated surface water finds limits to the value of case control studies
    PR Hunter, C Quigley. Communicable Disease and Public Health. Vol 1. No 4. December 1998. pp 234-238
  • A large outbreak of Cryptosporidiosis associated with a public water supply from a deep chalk borehole
    L Willocks, A Crampin, L Milne, C Seng, M Susman, R Gair, M Moulsdale, S Shafi, R Wall, R Wiggins, N Lightfoot. Communicable Disease and Public Health. Vol 1. No 4. December 1998. pp 239-243
  • Molecular characterisation of Cryptosporidium parvum from two large suspected waterborne outbreaks
    S Patel, S Pedraza-Diaz, J McLauchlin, DP Casemore. Communicable Disease and Public Health. Vol 1. No 4. December 1998. pp 231-233
  • Cryptosporidium and the safety of our water supplies
    David P Casemore. Communicable Disease and Public Health. Vol 1. No 4. December 1998. pp 218-219
     
1996
  • Cryptosporidiosis outbreak associated with an educational farm holiday
    M R Evans, D Garner. Communicable Disease Report. Vol 6. Review No. 3. 1 March 1996. R50-R51
  • Cryptosporidium in water supplies. The second report of the Badenoch Committee
    David Clapham. Environmental Health. Vol. 104. No. 4. April 1996. pp119-121
  • Cryptosporidiosis in children who visited an open farm
    GM Sayers, MC Dillon, E Connolly, L Thornton, E Hyland, E Loughman, MA O'Mahony, KM Butler. Communicable Disease Report. Vol 6. Review No. 10. 13 September 1996. R140-R144
  • A mixed outbreak of cryptosporidium and campylobacter infection associated with a private water supply
    L.A Duke, A.S Breathnach, D.R Jenkins, B.A Harkis & A.W Codd. Epidemiology and Infection. (1996) 11, pp 303-308
     
1995
  • Waterborne Cryptosporidiosis associated with a borehole supply
    D Morgan, M Allaby, S Crook, D Casemore, TD Healing, N Soltanpoor, S Hill, W Hooper. Communicable Disease Report. Volume 5. Review Number 7. 23 June 1995. R93-R97

  • Disinfection of public pools and management of fecal accidents
    Richard S. Kebabjian. Journal of Environmental Health. Vol. 58, Number 1. July/August 1995. pp 8-12
     
1993
  • Cryptosporidiosis in infancy and childhood mortality in Guinea Bissau, West Africa
    Kåre Mølbak, Niels Hø, Adam Gottschau, José Carlos Correia Sá, Liselotte Ingholt, Augusto Paulo José da Silva, Peter Aaby. British Medical Journal. Vol. 307. 14 August 1997. pp 417-420
  • Detection of Giardia and Cryptosporidium and enteric viruses in surface and tap water samples in Spain
    R De Leon, JB Rose, A Bosch, F Torrella, CP Gerba. International Journal of Environmental Health Research. 3, (1993) pp 121-129
     
1991
  • Nosocomial outbreak of cryptosporidiosis in AIDS patients
    Pernille Ravn, Jens D Lundgren, Poul Kjaeldgaard, Winnie Holten-Anderson, Niels Højlyng, Jens Ole Nielsen, Johannes Gaub. British Medical Journal. Vol. 302. 2 February 1991. pp 277-280
  • Cryptosporidium in cats: prevalence of infection in doestic and feral cats in the Glasgow area
    MMA Mtambo, AS Nash, DA Blewett, HV Smith, S Wright. The Veterinary Record. December 7, 1991. pp 502-504
     
1990
  • Cryptosporidiosis in England and Wales: prevalence clinical and epidemiological features
    Public Health Laboratory Service Study group. British Medical Journal. Vol. 300. 24 March 1990. pp 774-777
  • Waterborne Cryptosporidiosis and environmental health
    AM Grimason, HV Smith, PG Smith, ME Jackson, RWA Girdwood. Environmental Health. Volume 98. Issue 9. September 1990. pp 228-232
     
1985
  • Cryptosporidiosis
    DP Casemore Environmental Health. Volume 93. No. 5 May 1985
 
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