A few days ago I wrote about some research I’d done about pandemics. At the same time, I also learned about disease transmission. Those flu pandemics that hit fast and burned out after several months were all airborne pathogens (diseases). We’re all familiar with airborne disease – it’s why we cover our noses when we sneeze or our mouths when we cough. The disease spreads into the air through our coughing and sneezing and then other people breathe it in and are infected.

Then you have something like HIV or Hepatitis, which is a blood-borne pathogen. Again, something we’re all familiar with. Blood-borne diseases are harder to spread; they require fluid-to-fluid contact, such as through unprotected sex, using unclean needles or medical equipment (scalpels, etc), or blood transfusions. The current HIV pandemic has behaved very differently from a flu pandemic. Because it’s harder to spread, it took years rather than months. It’s no less deadly, though.

According to America’s Blood Centers, they do not accept blood from people infected with influenza. The risks of influenza (which is an airborne disease) being transmitted through blood transfusions is small, but possible. Meaning airborne diseases can sometimes also be blood-borne.

Third is food-borne illness. A good example is the recent scare with E Coli contaminated spinach. All that’s required for a food-borne disease to spread is for people to eat it with their food.

The fourth I’m going to mention is water-borne disease, like schistosomiasis. You’re most likely to catch these diseases by drinking, bathing or swimming in diseased water.

Many diseases are both food- and water-borne, like salmonella (which can cause dysentery or typhoid), botulism, or cholera.

Some other types of transmissions are skin-to-skin contact, or the (undoubtedly inadvertant) ingestion of fecal matter, or coming into contact with contaminated objects. For instance, the small pox disease was spread to Native Americans through diseased blankets.