In order to infect someone, a virus needs to escape its host, hitch a ride to the new host, and find a point of entry. This is known as transmission. But how exactly does that happen?
There are several types of virus transmission, but they can be generally divided into three groups.
The first one is by far the most common, and involves contact. If the contact is direct and close, infection can happen by touching the blood, sweat, saliva or other bodily fluids of an infected person; kissing and sex fall into this category too. Ebola is one of the viruses that spread through contact.
Indirect contact means that the virus is sitting on a surface or object somewhere, waiting for the next victim to stop by. These contaminated objects are known as fomites and are the reason we sanitise, launder, disinfect and clean any potentially contaminated stuff.
The second type of transmission is known as droplet transmission — this is your typical sneeze, cough, and leaning in too close while talking and spurting saliva. Viruses enjoy a brief ride in the air while cushioned inside a tiny droplet of mucus or saliva, which is then inhaled by the new host. Er, victim. A typical droplet transmitted virus is influenza.
The third type is the most devious, albeit also less common, and that’s airborne transmission. It starts out as a flying droplet, but instead of landing directly into someone else’s airways, an airborne virus is able to survive much longer once the original droplet has evaporated. Travelling via air currents, ventilation systems and the like, an airborne virus can infect someone who hasn’t even been close to the original host. Measles is one such nasty, by the way.
These types of transmission are also listed in order of difficulty to control contagion. Contact can be avoided to a great extent, while the occasional sneeze or airborne particle are more tricky to avoid.
And at this very point it is good to remember that the Ebola virus is not nearly as contagious as some other things out there. It spreads through contact, but you can’t catch it from the air, water of food. Now let’s hope it never evolves the ability to survive in the air.