Solutions for Preventing Infection in Institutional Environments Based on a New Hygiene Inspection Method

Hygiene Science

Contact infection is considered to be one of infection routes for COVID-19, influenza, and other infectious diseases. What happens is this: an infected person’s saliva droplets containing the virus adhere to an object, and an uninfected person comes in contact with it, brings the virus into the body, and then becomes infected.
Preventing infection involves keeping the surrounding environment hygienic and cutting off infection routes. Nowadays there is demand for simple ways to identify places contaminated with viruses for efficient hygiene control.

Many viruses are dispersed from the body together with saliva from infected people.

Components contained in saliva. Saliva contains proteins such as amylase and mucin, inorganic matter such as calcium and phosphoric acid, and oral bacteria and other components such as white blood cells and food residue. The saliva of an infected person contains the virus.

We considered employing immunochromatography, which uses antigen-antibody reactions, as a way to visually determine the amount of amylase, which is contained in saliva in high concentrations, present on the surfaces of an environment.
Before and after the test subjects did certain actions that disperse saliva (coughed, sneezed, and ate a meal), plates placed around the subjects were tested for amylase. Amylase was subsequently detected on the plates placed near the subjects, which were predicted to be contaminated with saliva droplets, and not detected on the plates placed away from the subjects.

Results of detecting amounts of amylase by immunochromatography. The results were judged based on the band densities of the test lines relative to the reference density. Band density of three-plus is equivalent to 125 ng of amylase, two-plus density to 62 ng, one-plus density to 31 ng, and the one-minus density to 0 ng.

Relationship between model behaviors, namely a cough, a sneeze and a meal accompanied by conversation, and test positions and the amylase test results. After a cough, one-plus band density was detected near the chest. After a sneeze, three-plus band density was detected near the feet, one-plus band density at a position approx. 2 m away, and one-minus band density at a position approx. 3 m away. After a meal accompanied by conversation, two-plus band density was detected near the chest and one-plus band density around the center of the table.

It is important to wipe surfaces with a disinfectant or the like to prevent places where hygiene is crucial from being contaminated with saliva droplets from infected people. We will apply the findings of this study to methods that contribute to efficient hygiene control.

Fabric and Home Care

Fabric and Home Care

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