Parenteral Transmission: Definition & Exposure

Instructor: Artem Cheprasov

Artem has a doctor of veterinary medicine degree.

Have you ever heard of the parenteral route? It is a way by which potentially deadly microbes may enter your body. This lesson describes this route as well as examples of how a person may be exposed.

What Is Parenteral Transmission?

Parenteral transmission refers to the passage or transfer of potentially dangerous pathogens via a way other than through the digestive system. Pathogens are disease causing agents. This term, pathogen, is most often applied to microorganisms such as viruses and bacteria.

First, let's find out why it's called parenteral transmission, and then let's learn about how people may be exposed to a pathogen via parenteral transmission.

The Parenteral Term

To understand what parenteral really refers to, we have to understand this term's basic parts. You'll notice that parenteral has 'enter' in it. This actually comes from the word part 'entero-'. 'Entero-' literally translated means to the intestines. However, in a broader context, it refers to most of the digestive tract including the stomach. So, when you eat on a daily basis, you are actually using enteral nutrition. Remember this word part's definition by recalling that food 'enters' your stomach and intestines after you swallow it.

The word parenteral also includes the suffix '-al', which means relating to. We can think of how we can all relate to someone named Al in order to help us remember that. Finally, parenteral has a prefix of 'par-'. Par means aside or apart from. Recall the definition of this by simply looking at the word a'par't. Putting it all together, parenteral transmission refers to transmission of a pathogen via any method, apart from things relating to the intestinal (digestive) tract. While that is technically true, in practice, this is commonly limited to methods of transmission that involve breaks in the skin as you're about to learn.


So, how do people get exposed to pathogens via parenteral transmission then? Well, as was recently mentioned, it all really boils down to a breakage of the skin via one way or another. For example, an injection relies on a syringe and needle or catheter. If that syringe, needle, catheter, or whatever substance is being delivered to the patient via the syringe or catheter is contaminated with a pathogen, then the person can become exposed via one of three main routes:

  • Intravenous. This means the injection is given directly into the vein. This, of course, means the skin is punctured by the needle prior to puncturing the vein.
  • Intramuscular. Such an injection route delivers the injection into the muscle. As you well know, the muscle lies below the skin, so a breakage of skin has to occur first.
  • Subcutaneous. This means the injection is delivered to an area right below the superficial-most layers of the skin. Obviously, the skin has to be punctured for this to occur.

This woman is being given an intramuscular injection.

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