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Cryptococcal Infection

In document Blue Book (Page 47-51)

Victorian Statutory Re q u i re m e n t

Notification not required.

Infectious Agent

Cryptococcus neoformans, an encapsulated yeast-like fungus.

C. neoformans var. neoformans (serotypes A & D).

C. neoformans var. gattii (serotypes B & C).

Clinical Features

Cryptococcal infection usually presents as a sub-acute or chronic meningo-encephalitis with headache and altered mental state.

Lung involvement may cause symptoms of lower respira-tory tract infection or may be asymptomatic.

The skin, bone and other organs are less frequently infected.

Public Health Significance and Oc c u r re n c e

Sporadic cryptococcal infections occur worldwide.

Method of Diagnosis

HIV-infected persons may have cryptococcal meningitis, even in the absence of inflammatory cells in the cerebro-spinal fluid (CSF).

CSF should be stained with an India ink stain.

CSF, blood, sputum and urine should be cultured for cryptococci.

CSF and serum should be tested for cryptococcal antigen.

Pulmonary cryptococcosis in non-HIV infected persons usually manifests as a nodule, which must be distin-guished from a malignancy (which may coexist).

Re s e r voi r

C. neoformans var. neoformans occurs worldwide, frequently in association with pigeon or other bird droppings.

C. neoformans var. gattii occurs in endemic foci in the tropical and sub-tropical world where certain eucalypts provide an ecological niche.

Mode of Transmission

It is transmitted by inhalation.

Communicability

Cryptococcal infection is not spread from person-to-person or animal-to-person-to-person.

Susceptibility

Persons with impaired immunity due to corticosteroid therapy, lymphoma and sarcoidosis are at increased risk of crytococcal infection.

Persons with AIDS are particularly prone and now constitute a majority of cryptococcal infection cases.

Control of Case

The diagnosis should be established.

The possibility of underlying HIV infection should be considered.

Referral to a specialist centre should occur.

Therapy for cryptococcal meningitis usually involves at least six weeks of antifungal medications: Amphotericin B in combination with 5-flucytosine.

Persons with AIDS then require lifelong suppressive therapy, usually with an imidazole antifungal agent.

Discrete lung lesions may need diagnosis by biopsy and the need for antifungal therapy depends upon the underlying health of the host.

Immunosuppressed persons are usually treated to prevent dissemination.

Control of Contacts

Contacts of cases need no specific follow-up.

Preventive Measures

Remove large accumulations of bird droppings.

Epidemic Measures

Clusters have not been reported.

C r y p t o s p o r i d i o s i s

Victorian Statutory Re q u i re m e n t

Statutory notification is not required.

Note

Notification if Cryptosporidium spp are isolated from water supplies, or are associated with a food or water-borne illness outbreak.

Infectious Agents

Cryptosporidium spp. (coccidian protozoa).

Clinical Features

Cryptosporidiosis is a parasitic protozoan infection that affects the gastrointestinal tract.

The major symptoms are watery diarrhoea associated with cramping abdominal pain.

The disease may sometimes be mild, but in persons with impaired immunity, particularly those with AIDS, it may be a life-threatening illness.

Public Health Significance and Oc c u r re n c e

Cryptosporidiosis occurs worldwide. Young children, the families of infected persons, homosexual men, travellers, health care workers and people in close contact with animals comprise most reported cases.

Small outbreaks may occur related to child care centres.

Substantial water-borne outbreaks have been reported in the United States in 1993.

Method of Diagnosis

The laboratory should be informed of clinical suspicion of cryptosporidiosis.

Oocysts may be identified by microscopy of faecal smears treated with a modified acid fast stain. A monoclonal antibody test is useful for detecting oocysts in faecal and environmental samples. Oocyst excretion is most intense during the first days of illness. Oocysts are rarely recovered from solid faeces.

ELISA assays have been developed for the detection of antibodies, but these are not in routine use.

Re s e r voi r

Humans, domestic and wild animals.

Modes of Transmission

Cryptosporidium spp. are spread by the faecal-oral route directly from person-to-person and animal-to-person, and via contaminated food and water.

Incubation Period

From one to 12 days, with an average of about seven days.

Period of Communicability

Cases may be infectious for as long as oocysts are excreted in the stool: from the onset of symptoms until several weeks after symptoms resolve.

Under suitable conditions, oocysts may survive in soil and be infective for up to six months.

Susceptibility and Resistance

People with normal immune systems usually have asymptomatic or self-limited symptomatic disease.

People with impaired immunity may experience pro-longed illness, depending on the course of their altered immune function.

Control of Case

• Exclude symptomatic persons from food handling and direct care of hospitalised and institutionalised patients until asymptomatic.

• Stress the importance of hand washing.

• Disinfect soiled articles.

• Exclude symptomatic persons from direct care of children in child care centres.

• Exclude children with diarrhoea from child care centres until their diarrhoea has ceased.

Tre a t m e n t

Symptomatic. Supportive care with fluid and electrolyte replacement and anti-diarrhoeal agents may be needed by severely affected cases, particularly those with underlying immune deficiency.

Control of Contacts

The diagnosis should be considered in symptomatic contacts.

Preventive Measures

• Educate the public in personal hygiene.

• Dispose of faeces in a sanitary manner.

• Insist on careful hand washing by persons in contact with animals.

• Filter or boil contaminated drinking water (chemical disinfectants such as chlorine are not effective against oocysts at the concentrations used in water treatment).

Epidemic Measures

Investigate clustered cases. Look for sources of infection such as water or raw milk supplies.

In document Blue Book (Page 47-51)