Which notified STEC cases need public health action? — The Association Specialists
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Which notified STEC cases need public health action? (23714)

Michelle Renwick 1 , Caitlin Pfeiffer 1 , Joy Gregory 2 , Dieter Bulach 1 , Simon Firestone 1
  1. Melbourne Veterinary School, University of Melbourne, Parkville, Victoria, Australia
  2. Victorian Department of Health, Melbourne, Victoria, Australia

Background:

The number of human Shiga toxin-producing Escherichia coli (STEC) notifications has risen in Victoria, Australia, since the gradual introduction of gastrointestinal multiplex diagnostic panels. Identifying the cases of greatest public health importance is essential to ensure efficient use of public health resources. A small proportion of STEC infections progress to haemolytic uraemic syndrome (HUS), a severe sequela. By identifying risk factors associated with HUS other countries have been able to prioritise which cases receive public health actions, but these factors may vary with epidemiological context. This study therefore aimed to describe the changes in notification data after diagnostic testing changed and identify factors associated with HUS.

Methods:

Surveillance data of 474 STEC and 65 HUS cases from the Victorian Department of Health, 2000-2020, were collated from the public health database and hard-copy documents. Piecewise Poisson regression was used to identify the start of an increasing trend in notifications. Seasonality, demographics, travel, rurality, serogroup, stx genes, case symptoms and comorbidities were described by time (before and after the start of the trend) and severity (HUS, STEC and STEC with atypical symptoms).

Results:

Notifications increased significantly after July 2014 amongst residents of metropolitan Melbourne and people >41 years old; more STEC cases had atypical symptoms and proportionally fewer cases had bloody diarrhoea or progressed to HUS. Notified HUS cases were more likely than other STEC cases to be aged 0-5 years, and have vomiting, bloody diarrhoea and STEC carrying the stx2 gene only.

Conclusion:

These results provide insight into the characteristics of STEC cases identified by the new testing protocols and factors associated with HUS consistent with findings from other countries. Further ongoing research involves integrated analyses of these data with genomic characterisation of the STEC isolates to identify predictors of which STEC cases are of the highest public health importance.