Epidemiology and Infection

Research Article

Evaluating measles surveillance using laboratory-discarded notifications of measles-like illness during elimination

Y.-H. J. WANGa1a2 c1, R. M. ANDREWSa3, H. KELLYa4 and S. B. LAMBERTa1a5

a1 National Centre for Epidemiology and Population Health, Australian National University, Canberra, Australia

a2 Communicable Diseases Section, Department of Human Services, Victoria, Australia

a3 Clinical Epidemiology and Biostatistics Unit, Murdoch Childrens Research Institute and Department of Paediatrics, University of Melbourne, Victoria, Australia

a4 Victorian Infectious Diseases Reference Laboratory, Victoria, Australia

a5 Vaccine & Immunisation Research Group, Murdoch Children's Research Institute and School of Population Health, University of Melbourne, Victoria, Australia

SUMMARY

For jurisdictions implementing measles elimination strategies, a minimum surveillance benchmark of 1/100 000 population per year measles-like illness (MLI) cases initially notified, but then rejected based on laboratory testing was proposed. We used this standard to assess the quality of the Victorian enhanced measles surveillance between 1998 and 2003. Victorian enhanced measles surveillance includes interviews with notified cases and confirmatory laboratory testing for notifications. We found 72% (918/1281) of measles notifications were discarded after testing. The median annual rate of discard was 2·9/100 000. The annual discard rate was inversely associated with the age of the notifications, and measles negative with no other diagnosis made was the most common laboratory outcome. The annual rates of discarded notifications in Victoria were consistently above the minimum recommended standard. The rate of discarded MLIs as a surveillance threshold should be useful in measles endemic regions, but may require modification where disease elimination has occurred.

(Accepted February 09 2007)

(Online publication March 12 2007)

Correspondence:

c1 Author for correspondence: Dr Y.-H. J. Wang, Centre for Epidemiology and Population Health Research, Macfarlane Burnet Institute for Medical Research and Public Health, GPO Box 2284, Melbourne, VIC 3001, Australia. (Email: julie@burnet.edu.au)

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