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Cryptosporidiosis

Queensland Health Guidelines for Public Health Units

Revision history

Version Date Changes
1.0 September 2015

 

Infectious agent

For further information please contact your local doctor, or Public Health Unit.

Human infections of cryptosporidium are caused predominantly by Cryptosporidium parvum and Cryptosporidium hominis. Cryptosporidium is a protozoan parasite of the gastrointestinal, biliary and respiratory tracts of humans and of birds, poultry, fish, reptiles, domestic animals and cattle and sheep.  Occasional infections are caused by other species of cryptosporidium.

Notification criteria

Clinical Evidence
Not applicable 

Epidemiological Evidence

Not applicable

Laboratory Definitive Evidence

Detection of Cryptosporidium oocysts in a faecal specimen. 

Community Outbreak Criteria

Clusters of cases in an area or an institution, or a significant increase in notified cases in the community, compared to historical data.

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Notification procedure

Pathology laboratories

To notify on:

Detection of Cryptosporidium oocysts in a faecal sample,

OR

Detection of Cryptosporidium specific antigen,

OR

Detection of Cryptosporidium by NAT.

Reporting to NOCS

Report only confirmed cases.

Confirmed Case
A confirmed case requires laboratory definitive evidence.

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Public health significance and occurrence

Occurs worldwide. Increasingly recognised as a cause of both sporadic and epidemic human disease (epidemics due to contaminated water supplies can affect many people). Most cases are in children under 10 years. Outbreaks in which a high proportion of cases are adults suggests waterborne transmission.  Asymptomatic infections are common and constitute a source of infection for others.

The oocyst excreted in the faeces is the infective form. It is highly resistant to chlorine as used in water treatment, and with a diameter of 4-6µm treatments considered effective in removing oocysts are micro filtration, nano filtration, and ultrafiltration and reverse osmosis. With regard to sand filtration, optimisation of filtration (slow or rapid) is required to achieve complete removal of the oocysts. Oocysts can remain infective for 2-6 months in moist environmental conditions.

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Clinical features

Acute gastroenteritis which is self-limiting in healthy persons but may last up to 30 days. Profuse watery diarrhoea with crampy abdominal pain. May be preceded by anorexia and vomiting in children. Fever and malaise may be present. In immunocompromised persons e.g. people with AIDS, the infection can be severe, prolonged and even fatal.

Reservoirs

Humans, cattle and other domesticated and wild animals.

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Mode of transmission

Person-to-Person: Via faecal-oral route from patients or carriers. Infection may occur after the ingestion of very few oocysts. Easily transmitted in settings such as day care centres.
Water borne: From contaminated untreated or inadequately treated drinking water supplies or recreational water such as dams and swimming pools. Oocysts are highly resistant to the chemical disinfectants used for purifying drinking water.
Animal-to-Person: Via direct contamination, especially from calves and lambs on farms or in children’s zoos.
Food borne: Via direct ingestion of raw or contaminated food.

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Incubation period

Variable; a likely range of 1-12 days, with an average of 7 days.

Period of communicability

Oocysts appear in the stools at the onset of symptoms and may continue to be excreted for several weeks after symptoms cease. Outside the body, they may remain infective for 2-6 months or longer in a moist environment.

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Susceptibility and resistance

People with intact immune systems may have asymptomatic or self-limited symptomatic infections. It is not clear whether reinfection or latent infection with reactivation can occur. Those with impaired immunity generally clear their infections when the causes of immunosuppression are removed. Children younger than two (2) years, animal handlers, travellers, men who have sex with men, and close personal contacts of infected individuals are particularly prone to infection.

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Management

Cases

Investigation
Investigate for source of infection and contacts.
 
Restriction
Enteric precautions during acute illness. Treatment is symptomatic only. Exclude ill patients from food handling, childcare or patient care until at least 48 hours after diarrhoea has ceased. Thorough handwashing after defecation should be stressed. People with cryptosporidiosis should not enter a swimming pool until 14 days after symptoms have ceased, due to the potential for prolonged excretion of oocysts.

Counselling
Advise about mode of transmission and personal interventions, especially handwashing.

Contacts

Contact Tracing
Not usually.

Definition
People who have had close contact with the case.  

Investigation
The contacts of sporadic cases are not usually investigated. Stool cultures from asymptomatic contacts are only necessary in those who are in situations where the spread of infection is particularly likely (such as day-care centres, hospitals).

Prophylaxis
Not applicable                      

Counselling
Symptomatic contacts should be excluded from food handling and the care of children or patients until investigated, or until symptoms cease.

Other control measures

Concurrent Disinfection
Faeces can be discharged directly into modern sewage disposal systems. Articles soiled with faeces should be subjected to thorough laundering in a hot wash and be thoroughly dried. Soiled nappies should be soaked in a product rated for nappy sanitising, according to label directions.

Community outbreaks/epidemics

  • Investigate to determine source, including water, food and animal contacts.
  • Investigate common exposures to possible sources, eg. day care centres, swimming pools, farm visits.
  • Stress the importance of hand washing after defecation.
  • Pay attention to environmental cleaning particularly in institutions, and especially of toilet areas.

If swimming pool transmission is suspected, refer to the Queensland Health Swimming and Spa Pool Water Quality and Operational Guidelines, 2004.

 

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Preventive measures

  • Washing hands thoroughly after using the toilet, changing nappies and before handling food or eating
  • washing the hands of toddlers and babies after a nappy change
  • washing hands after contact with pets, and after cleaning up animal faeces
  • washing hands after gardening or other direct contact with soil
  • washing hands after contact with cattle and other farm animals
  • washing fruit and vegetables before eating them
  • not eating or drinking unpasteurized milk products
  • not drinking untreated water and inadequately filtered water and boiling untreated water or water of unknown quality for a t least one minute before drinking
  • not swallowing water in swimming pools or other recreational water
  • avoid swimming in natural waters (rivers, creeks, dams, surf) within a week after heavy rain
  • not sharing linen and towels during diarrhoea and for 2 weeks after diarrhoea has stopped.

Water filters with a pore size of 1µm or smaller are effective in removing cryptosporidia.

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Feedback

Report to notifying agency, if an outbreak investigation is conducted.

Summary

Prepare a report of the investigation for the Communicable Diseases Branch, Queensland Health, on request in sporadic cases and always for outbreaks. Complete an outbreak summary form for the OzFoodNet outbreak register.

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References

Heymann, David L. (Ed). 2015. Control of Communicable Diseases Manual, 20th edition.  American Public Health Association: Washington.

Queensland Health. 2004. Swimming and Spa Pool Water Quality and Operational Guidelines, Queensland Government

Mandell, Douglas and Bennett’s Principles and Practice of Infectious Diseases, 8th Ed. 2015 edited by John E. Bennett, Raphael Dolin and Martin I. Blaser. ELSEVIER SAUNDERS.

Queensland Health.  2014.  Queensland Notification Criteria – Guidelines for Laboratories.

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Last updated: 21 September 2015