Bacteria and viruses have been around since the earliest life on Earth emerged, and in that time they’ve found many ways to spread between hosts:

  • Person to person contact Through the air
  • Animal to human contact
  • Touching a surface (faucet, counter, door knob) that is contaminated by a sick person touching it
  • Through food
  • Through bodily fluids contaminating other surfaces or becoming airborne from a toilet flush

The most common way germs are spread

Researchers say that most people catch viruses through indirect contact, say by touching a door knob that was handled by someone contagious and then touching their face. (Hesman-Saey, 5-9-2020) Studies have found that we absentmindedly touch our eyes, nose and mouth as often as every 2 \12 minutes. (JabI’, 2020) Some people do so even more than this. Bacteria and viruses hitch a ride as we hand-deliver them into the orifices of our body. This is the reason why hand-washing is so important to keep from getting sick.

Germs spread through the air
Many illnesses are airborne pathogens-launched into the air by sick people and then breathed in by others. The truth is that you have experience with the spread of aerosol particles every day. Whenever you smell popcorn from across the room, cigarette smoke in a restaurant, or a foul smell when Dad takes off his socks, you’re experiencing the spread of aerosol particles. They are sent aloft and then carried around the room by air currents even without any acceleration.

Coughing and sneezing IS one way this happens. A sneeze droplet can travel up to 8 melers (27 feel), and even a nleler away from the mouth, cough droplets are traveling at a speed of I meter per second. “It’s not a speed you can avoid by turning your head away,” says fluid mechanics engineer Eric Savory, who has studied the topic.

Yet ordinary talking is likely a bigger culprit, as germs can be spread through everyday conversation. Talking produces thousands of aerosols from the lungs for every saliva droplet from the mouth. (Hesman-Saey, 5-9-2020)

Buildings & how they affect the flow of germs
The ease with which germs spread can depend on various factors,. Even buildings and infrastructure can playa role. “If rooms are poorly ventilated, the microbes people exhale or the stool droplets that permeate the air during a toilet flush get more heavily concentrated in the air over time.” (Wenner-Moyer, 2018, p. 53) For example, when there was an outbreak of infectious disease at one apartment complex, it was found that poor drainage allowed viruses from a person who was sick to spread from floor to floor through toilet pipes, infecting people on lower floors even though they had no direct contact with the sick person.

Germs spread through food & food workers
Another common way germs are spread is through food preparation. One study found that 70% of restaurant managers work while sick either because they can’t get time off or can’t afford to take it. (Wenner-Moyer, 2018)

Food you buy from the grocery store can also be contaminated. According to food safety expert JeffNelkon, it’s safe to assume that produce that’s out for display in the grocery store has been handled by at least 10 people. (Cowan, 3-20-2020) If any of them were sick, they can transfer these germs through touch or when you eat the food raw.

Why germs are spread more easily during the winter
Ultraviolet light in sunlight can damage pathogens and limit their spread. “Sunlight kills most pathogenic microbes quite rapidly,” says microbiologist John Postgate. This is one of the reasons colds are much less common throughout the summer months. (Broad, 4-25-2020) When people spend more time outdoors, it’s harder for pathogens to take hold and spread throughout the population.

Germs spread from animals to humans
Animal-to-human transmission is a routine cause of new or mutated viruses. While some, such as the infamous “bird flu” or “swine flu” are pretty definitively known to be caused by animal-to-human transmission, it’s likely that this only scrapes the surface.

“There’s a laundry list of pathogens that infect both humans and animals that you find in urban rats,” says infectious disease researcher Gregory Glass. Yet because doctors and scientists seldom look for this path of transmission, recorded cases are next to zero. (Wenner-Moyer, 2018)

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