Optimal number of samples to test for institutional respiratory infection outbreaks in Ontario

• Published in: Epidemiology and infection Vol. 141; no. 8; pp. 1781 - 1785
• Main Authors: PECI, A., MARCHAND-AUSTIN, A., WINTER, A-J., GUBBAY, J. B.
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01-08-2013
• Subjects: Adenoviruses; Aged; Aged, 80 and over; Biological and medical sciences; Child; Coronaviruses; Disease Outbreaks - statistics & numerical data; Fundamental and applied biological sciences. Psychology; Humans; Infant, Newborn; Influenza; Influenza, Human - epidemiology; Influenza, Human - virology; Laboratories; Microbiology; Multiplex Polymerase Chain Reaction - economics; Multiplex Polymerase Chain Reaction - methods; Ontario - epidemiology; Organisms; Other Infections; Public health; Respiratory syncytial virus; Respiratory Tract Infections - epidemiology; Respiratory Tract Infections - virology; Sampling Studies; Short Report; Viruses; Canada; North America; Ontario; America; United States > US; laboratory tests; outbreaks; Influenza; respiratory infections; Respiratory disease; Epidemiology
• ISSN: 0950-2688; 1469-4409
• DOI: 10.1017/S0950268812002531

The objective of this study was to determine the optimal number of respiratory samples per outbreak to be tested for institutional respiratory outbreaks in Ontario. We reviewed respiratory samples tested for respiratory viruses by multiplex PCR as part of outbreak investigations. We documented outbreaks that were positive for any respiratory viruses and for influenza alone. At least one virus was detected in 1454 (85·2%) outbreaks. The ability to detect influenza or any respiratory virus increased as the number of samples tested increased. When analysed by chronological order of when samples were received at the laboratory, percent positivity of outbreaks testing positive for any respiratory virus including influenza increased with the number of samples tested up to the ninth sample, with minimal benefit beyond the fourth sample tested. Testing up to four respiratory samples per outbreak was sufficient to detect viral organisms and resulted in significant savings for outbreak investigations.