infection

Blogpost 055 – The Prodromal Phase of Infection

Dear friends,

In our last post, we began a discussion of infection and what are commonly considered it four distinct phases.

By way of a quick review, these are:

  • The incubational phase
  • The prodromal phase
  • The acute phase
  • The convalescent phase

The incubational phase, as you’ll recall, is that period of time from initial contact with an infectious agent – be it bacterial, viral, or otherwise – and the onset of initial symptoms.

Those symptoms bring us to the second phase of infection: the prodromal period. But, what is the cause of this period? Why doesn’t the incubational one just continue?

The Soldier Becomes an Army

The word “prodromal” means “precursory,” in the sense of a forerunner. So, if you’re rightly thinking that acute infection is the full flowering, as it were, of symptoms, then its forerunner stage would be whatever leads to the appearance of those symptoms.

Hey, I’ve been quietly sitting here enjoying the buffet. But now, it looks like it’s time to open up a chain of restaurants!

That forerunner could be likened to a lone soldier. But, one soldier doesn’t make an army. So, our pathogen starts increasing its footprint within its infected host by means of reproduction.

Defenses Are Down

You’ll also recall that, in order for that to happen in the case of B. burgdorferi, its host’s immune system or autonomic nervous system (or both) needs to be in a state of functional compromise. In other words, something’s not working properly.

It’s almost as if the infecting bug says to itself, “Hey, I’ve been quietly sitting here enjoying the buffet. But now, it looks like it’s time to open up a chain of restaurants!” Again, it can do this (i.e., begin reproducing and colonizing) only because the terrain is ripe for colonization. (Hint: if you don’t want to get sick, start by actively pursuing health.)

The Meaning of Initial Symptoms

But what about these initial symptoms? Are they conclusive? Do they necessarily identify the underlying infection and its cause? Not necessarily. In fact, as the following excerpt from the online edition of the textbook Boundless Microbiology explains:

Related  Blogpost 054 – Infection

“In this phase, the numbers of the infectious agents start increasing and the immune system starts reacting to them. It is characterized by early symptoms that might indicate the start of a disease before specific symptoms occur. Prodromes may be non-specific symptoms or, in a few instances, may clearly indicate a particular disease. For example fever, malaise, headache and lack of appetite frequently occur in the prodrome of many infective disorders. It also refers to the initial in vivo round of viral replication.”

So, what’s the take away from all of this? Simply: once symptoms begin manifesting themselves, you are actively infected. That we know. Exactly what is infecting you may still be unclear. Regardless, it’s time to figure out what’s wrong and start fixing it, and the sooner the better!

Otherwise, you could find yourself in the third phase of infection. If the prodromal period is like invasion, then the acute one is akin to occupation. On that ominous note, I’ll leave you. We’ll pick up there in our next post.

For now, keep well, and listen to your body!

All the best,

Dr. Blanche Grube

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