Salivary amylase as a monitoring index for respiratory infectious virus contamination

Abstract Contact infection is a common route of respiratory infections, including that caused by severe acute respiratory syndrome coronavirus 2. Monitoring of viral contamination of environmental surfaces is critical for implementing appropriate hygiene measures and reducing the risk of viral transmission. We assessed the novel utility of the salivary amylase test on environmental surfaces for monitoring the viral contamination risk. An assay based on the principle of immunochromatography was used to detect amylase. Contamination of plastic substrates with amylase and viral genes over time showed similar patterns under laboratory conditions. Moreover, amylase was detected on the surfaces surrounding individuals who performed behaviors (e.g., coughing and sneezing) that spread droplets. Accordingly, detection of amylase might indicate the presence of viral genes in cases where droplets from infected individuals were retained on surfaces. Environmental surfaces (n = 186) located in public facilities were investigated and amylase was highly detected in the food courts (66.7−75.0%) and washbasins of hotel guest rooms (100%). However, no correlation was observed between the adenosine triphosphate level (a marker of hygiene control) and the sites positive for amylase. Our research provide a method revealing sites of viral contamination and lead to the establishment of an appropriate infection control system.