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Infection with Shiga-like toxin (verotoxin) producing strains of Escherichia coli (SLTEC or VTEC)* has the potential to cause severe and life threatening illness, including haemorrhagic colitis (HC), haemolytic uraemic syndrome (HUS) and thrombotic thrombocytopaenic purpura (TTP). Such strains are found in some animals, and are transmitted to humans through ingestion of undercooked meat (especially minced beef), or other food or water contaminated with animal faeces. Swimming in faecally contaminated lakes has also resulted in cases. Secondary transmission from person to person can occur. While cases are usually sporadic in Australia, two outbreaks, resulting in one death, have been documented. Large outbreaks have occurred overseas and reports of foodborne illness resulting from SLTEC strains are increasing world wide.

To improve the understanding of the epidemiology of these infections and facilitate the public health response to cases, a number of States (Queensland, New South Wales, South Australia, Western Australia and Tasmania) have already made SLTEC/VTEC infections and/or HUS/TTP notifiable conditions, and the other States and the Territories are in the process of, or considering, doing so.

On 22 July 1998, members of the Communicable Diseases Network Australia New Zealand (CDNANZ) endorsed case definitions for national reporting of SLTEC (VTEC) infections, HUS and TTP in Australia.** The Network agreed to report cases to the National Notifiable Diseases Surveillance System (NNDSS) for publication in CDI. Cases are reported for the first time in this issue (page 224). The case definitions and explanatory notes are provided in the box below.

National surveillance of HUS is also being undertaken by the Australian Paediatric Surveillance Unit, who are conducting an active surveillance study of HUS in children under the age of 16 years.

CDNANZ case definitions for the national surveillance of SLTEC (VTEC), HUS and TTP

Shiga-like toxin (verotoxin) producing E. coli (SLTEC, VTEC)

In a clinical specimen from a person with bloody diarrhoea, haemolytic uraemic syndrome (HUS) or thrombotic thrombocytopaenic purpura (TTP):

• isolation of Shiga -like toxin (verotoxin) producing E. coli;

OR

• identification of Shiga toxin (verotoxin) in E. coli OR the gene associated with the production of Shiga toxin (verotoxin) in E. coli.

Note: The SLTEC/VTEC case definition is for the reporting of confirmed cases to the National Notifiable Diseases Surveillance System. States and Territories may use more sensitive case definitions to identify possible cases for public health follow up. The case definition is not intended to prescribe the laboratory tests that should be done to screen for SLTEC/VTEC infections.
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Haemolytic uraemic syndrome (HUS)

A case diagnosed as haemolytic uraemic syndrome (HUS) by a specialist physician, paediatrician, or paediatric nephrologist.

Note: The diagnosis of HUS will generally require the following:

• microangiopathic haemolytic anaemia (Hbg/dl and microscopic evidence of fragmented red cells);

AND

• acute renal impairment (oliguria or anuria, and elevated serum urea, and elevated serum creatinine);

AND

• thrombocytopaenia (platelets d,000/mm³)

However, the platelet counts may be normal or even high, particularly later in the disease.

Thrombotic thrombocytopaenic purpura (TTP)

A case diagnosed as thrombotic thrombocytopaenic purpura (TTP) by a specialist physician, paediatrician, or paediatric nephrologist.

Note: The diagnosis of TTP will generally require the following:

• microangiopathic haemolytic anaemia (Hbg/dl) and microscopic evidence of fragmented red cells);

AND

• acute renal impairment (oliguria or anuria, and elevated serum urea, and elevated serum creatinine);

AND

• thrombocytopaenia (platelets d,000/mm³)

Footnotes
* also known as enterohaemorrhagic E. coli (EHEC)
**VTEC is already nationally reported in New Zealand.

This article was published in Communicable Diseases Intelligence Volume 22, No 10, 1 October 1998.