Koch's postulates

Welcome back.

In this final episode for chapter 13, I'm gonna talk about how infections spread and how Koch's postulates helped us understand the microbe relationship to diseases.

Portals of exit are the routes pathogens use to leave the body and move on to a new host.

In many cases, these directly mirror the portals of entry we already discussed.

Lyme disease caused by Borrelia burgdorferi can be difficult to fully eliminate because the bacteria disseminate in the body and persist in tissues like joints and the nervous system.

These tricky spirochetes hide in less accessible areas to avoid the immune defenses and antibiotics, which contributes to lingering or recurrent symptoms, even with treatment.

Now, how do we know which microbe is causing a disease? Etiology is the cause of disease, and historically, this was addressed using Koch's postulates, a set of criteria used to link a specific microorganism to a specific disease.

The idea was very simple.