From: Philip
Sent: Monday, February 19, 4:24 PM
Subject: Public health question
Hi Tom: I was reading a placard at a museum that spoke about a huge fine for people spitting on the street because an epidemic was underway. It raised the following question in my mind: I've often noticed that spitting on the street is frowned upon; but I've always considered it to be a quick and efficient way of disposing of an inconvenient piece of mucus: No wasted tissue paper, no environmental impact, no handling a germ laced piece of tissue, no placing a contaminated tissue in a garbage container where it could infect custodial personnel, & no carrying a soiled tissue in your pocket (or sleeve -- gross). Instead, quickly deposit the material on the street where it soon evaporates. If someone steps on it only a shoe sole is contaminated, and a shoe sole is seldom in contact with an infection conduit on another person. What do you think?
So, when you sneeze or spit, the small percentage of the expelled material that leaves as microscopic droplets, and remains suspended in the air at the level of everyone's heads to be breathed in, is actually the infectious concern. The droplets only remain suspended for a short time before they are dessicated by the surrounding air and no longer infectious.
"Cold and flu virus-laden droplets may remain infectious for several hours, depending on where they fall. Viruses generally remain active longer on stainless steel, plastic and similar hard surfaces than on fabric and other soft surfaces."
From the perspective of a respiratory virus, this is a very efficient mechanism to increase your population. You infect a host and irritate the respiratory mucosa in such a way as to cause sneezing and coughing and spitting, which very effective at spreading infection to nearby hosts. In addition to this, the viruses are constantly mutating and changing their genetic makeup as a clever way of escaping or bypassing detection by the immune system.
I'm reading a very interesting book by Bill Bryson called "At Home," and he makes the interesting point that a lot of human disease was accelerated when we switched from Neolithic nomadic people to "sedentism," living in cities, not only because we were in close proximity to each other, but because we lived alongside commensal organisms from rats to cats to pigs that were vectors for myriad diseases.
All of this to say that the kleenexes or sleeves we sneeze or spit into are a supposed effort to contain the droplets and minimize their spread. Unfortunately, any time you touch your face and especially its orifices, some droplets go onto our hands. Our predilection for shaking hands with, and hugging, people around us is an annoyingly convenient way for viruses to spread. (Or, from the viruses' point of view, our very obliging habit or frequently shaking hands and hugging...)
Preventive efforts have been aimed at encouraging kids (and everyone) to sneeze into their upper sleeve, instead of their hands or cuffs of their sleeves, because your have are unlikely to touch your upper sleeve for the hour or two that the virus relations infectious on your sleeve.
I've observed that flu epidemics tend to spike just after Christmas, a time if year when we all spend a lot of time hugging many relatives, then stuff ourselves into close quarters in airplanes for several hours to ensure that we breathe droplets from as many people as possible. ("a surge of cases in January could have been caused by children returning to school after the Christmas break and spreading the virus."
https://www.google.com/amp/s/www.voanews.com/amp/4227099.html)
Frequent hand washing, or use of hand sanitizer, is the best defense against spreading viruses.
