Cryptosporidiosis

Part of the Communicable Disease Control Manual

Chapter reviewed and updated in December 2017. A description of changes can be found at Updates to the Communicable Disease Control Manual.

Contents


Epidemiology in New Zealand

Cryptosporidiosis is caused by infection with the coccidian protozoan Cryptosporidium spp.

More detailed epidemiological information is available on the Institute of Environmental Science and Research (ESR) surveillance website.

Further information on foodborne illness is available on the Ministry for Primary Industries website.

Case definition

Clinical description

An acute illness that includes symptoms of diarrhoea (may be profuse and watery) and abdominal pain. The infection may be asymptomatic but to meet the case definition the individual must have compatible symptoms.

Laboratory test for diagnosis

  • Laboratory definitive evidence for a confirmed case requires detection of Cryptosporidium spp oocysts in a faecal specimen by at least one of the following methods[1]:
  • Cryptosporidium antigen detection by either:
    • detection of direct fluorescence using monoclonal antibodies
    • detection of antigens using a rapid antigen test
    • enzyme immunoassay.
  • detection of Cryptosporidium nucleic acid
  • visualisation by direct microscopy detection of Cryptosporidium cysts.

Case classification

  • Under investigation: A case that has been notified, but information is not yet available to classify it as probable or confirmed.
  • Probable: A clinically compatible illness that either is a contact of a confirmed case of the same disease or has had contact with the same common source – that is, is part of a common-source outbreak.
  • Confirmed: A clinically compatible illness accompanied by laboratory definitive evidence.
  • Not a case: A case that has been investigated and subsequently found not to meet the case definition.

Spread of infection

Reservoir

The gastrointestinal tract of humans (C. hominis) and animals (C. parvum) including cattle, sheep, pigs, cats, dogs, poultry and fish. Asymptomatic carriage.

Incubation period

Probably 1–12 days, with an average of 7 days.

Mode of transmission

Faecal-oral, including person to person, from infected animals or from contaminated water or food.

Period of communicability

Oocysts, the infectious stage, appear in the faeces at the start of illness and are excreted for several weeks after symptoms resolve.

Notification procedure

Attending medical practitioners or laboratories must immediately notify the local medical officer of health of suspected cases. Notification should not await confirmation.

Management of case

Investigation

Obtain a history of contact with animals, consumption of untreated water, recreational water contact, overseas travel, exposure to faeces or contact with other symptomatic cases.

Investigate further if there is an outbreak, or if the case is in a high-risk occupation, such as a food handler or a staff member at an early childhood service, or attends an early childhood service (see ‘Other control measures’ below).

Ensure stool samples from people with diarrhoea have been tested for Cryptosporidium spp.

Restriction

In any health care facility, only standard precautions are indicated in most cases; if the case is diapered or incontinent, apply contact precautions for the duration of illness.

In the case of immunocompromised people, there is currently no available chemotherapeutic agent that can be used to treat the infection, hence infection prevention and control are of major importance to protect such people. For further details, refer to the exclusion and clearance criteria in Appendix 2: Enteric disease.

Cases should not use public swimming pools until 2 weeks after symptoms have resolved.

Cases should be particularly careful not to transmit disease to immunocompromised people, this includes avoiding close physical contact with immunocompromised individuals until 2 weeks after symptoms have resolved.

Counselling

Advise the case and their caregivers of the nature of the infection and its mode of transmission.

Educate about hygiene, especially hand cleaning, and the risk of co-bathing with siblings if the case is a child.

Management of contacts

Definition

All people who have had close physical contact (for example, household) with a symptomatic case or who have been exposed to the same animal, water, food or other material suspected to be the source of infection.

Counselling

Advise all contacts to seek early medical attention if symptoms develop.

Other control measures

Identification of source

Check for other cases in the community. Investigate potential food, water or swimming pool sources of infection only if there is a cluster of cases or an apparent epidemiological link.

If indicated, check water supply for microbiological contamination and compliance with the latest New Zealand drinking-water standards (Ministry of Health 2008).

If a water supply is involved, liaise with the local territorial authority to inform the public. Advise on the need to boil water.

If indicated, check swimming pools for compliance with the Standard for Pool Water Quality (NZS 5826:2010). Liaise with the local territorial authority staff to investigate potential water or pool sources of infection.

Disinfection

Clean and disinfect surfaces and articles soiled with stool. For more details, refer to Appendix 1: Disinfection.

Health education

Consider a media release and direct communication with relevant early childhood services, schools and health professionals to encourage prompt reporting of symptoms. In communicating with doctors, include recommendations regarding diagnosis and infection control.

Hand-cleaning facilities should be available and used after contact with animals. Young children should be supervised during contact with animals and during hand cleaning. Food-related activities should be separated from areas that house animals.

In early childhood services or other institutional situations, ensure satisfactory facilities and practices regarding hand cleaning; nappy changing; toilet use and toilet training; preparation and handling of food; and cleaning of sleeping areas, toys and other surfaces.

Educate the public about safe food preparation (see Appendix 3: Patient information).

Reporting

Ensure complete case information is entered into EpiSurv.

Where food/food businesses are thought to be involved inform the Ministry for Primary Industries.

If a cluster of cases occurs, contact the Ministry of Health Communicable Diseases Team and outbreak liaison staff at ESR, and complete the Outbreak Report Form.

References and further information


[1]     Once confirmed, the sample is anonymised and sent to Massey University for genotyping.

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