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Cryptosporidiosis

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Reporting Obligations

Confirmed and suspected cases shall be reported to the local Health Unit.

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Epidemiology

Aetiologic Agent

Cryptosporidium are oocyst-forming coccidian protozoa. Oocysts are excreted in feces of an infected host. The most common species causing disease in humans are C. hominis, which only infects humans, and C. parvum, which infects humans, cattle and other mammals.

Oocysts may survive for 2–6 months in a moist environment. Cryptosporidum is resistant to most disinfectants including 3% hypochlorite, iodophors, and 5% formaldehyde and can survive for days in treated recreational water venues.

The infectious dose is low; studies have demonstrated that the ingestion of ≤10 C. hominis or C. parvum oocysts can cause infection in healthy persons.

Clinical Presentation

Cryptosporidiosis is a parasitic infection that commonly presents as gastroenteritis. The major symptom is diarrhea associated with cramping and abdominal pain. In children, diarrhea can be watery and profuse preceded by anorexia and vomiting. General malaise, fever, anorexia, nausea and vomiting occur less often. Symptoms often wax and wane but remit in less than 30 days in most immunologically healthy people. Asymptomatic infections are common and constitute a source of infection for others.

Cryptosporidiosis in immunocompromised individuals (such as those with HIV) may lead to more severe clinical manifestations such as pancreatitis and liver cirrhosis. They may be unable to clear the parasite or their symptoms can relapse.

Modes of Transmission

Fecal-oral, which includes person-to-person, animal-to-person, waterborne (recreational or drinking water) and foodborne transmission.

Incubation Period

Not known precisely; 1–12 days is the likely range with an average of about 7 days.

Period of Communicability

Oocysts, the infectious components of the parasites life cycle, appear in stool at the onset of symptoms and are infectious immediately upon excretion; duration of post-symptomatic oocyst excretion varies from several weeks to months. The duration of oocyst infectiousness in the environment under suitable soil conditions can range from 2 to 6 months.

Symptoms can last for 30 days or less in healthy hosts, or longer in immunocompromised.

Risk Factors/Susceptibility

Persons with intact immune function usually have asymptomatic or self-limiting illness. It has been estimated that 10–20% of AIDS patients develop infection at some time during their illness. Those who are particularly prone to infection include children under two, animal handlers, travelers, men who have sex with men and close personal contacts of infected individuals (family, healthcare and daycare workers).

Diagnosis and Laboratory Testing

Diagnosis is through demonstration of Cryptosporidium oocysts in appropriate clinical specimen (e.g. stool, intestinal fluid, or small bowel biopsy) or through detection of Cryptosporidium DNA or demonstration of Cryptosporidium antigen by an approved method (e.g. EIA, ICT).

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Treatment and Case Management

Treatment is under the direction of the patient’s health care provider. There is no specific treatment except rehydration when indicated.

Inform patient that symptomatic cases will be excluded from conducting activities in high-risk settings such as the food industry, healthcare, or daycare, until 24 hours after symptoms resolve.

Provide education about the illness and how to prevent spread, emphasizing strict hand hygiene.

Patient Information

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References

Ministry of Health and Long-Term Care, Infectious Diseases Protocol, 2019.