What is the Difference Between Autoinfection and Retroinfection?

Autoinfection and retroinfection are two processes of reinfections where a pathogen inhabits the same host indefinitely. Both types of infections facilitate the pathogen to live within the host, but they differ in the way the infection occurs:

• Autoinfection: This type of infection happens when the pathogen already present in the body reinfects the host. It typically occurs from the anus to the mouth of the host, as in the case of Enterobius vermicularis, where eggs hatched by the pathogen are transmitted primarily from the anus to the mouth of the host.
• Retroinfection: This type of infection occurs when the third stage of the pathogen's larvae migrate back to the host through the same route. For example, in the case of Enterobius vermicularis, the larvae may migrate back into the rectum and to the small intestine, restarting the life cycle of the worm. Retroinfection generally occurs from the anus to the colon.

In summary, the key difference between autoinfection and retroinfection is that autoinfection is a reinfection by a pathogen already present in the body, while retroinfection is a type of infection where the third stage larvae of the pathogen migrate back to the host through the same route.

Comparative Table: Autoinfection vs Retroinfection

Here is a table summarizing the differences between autoinfection and retroinfection:

In both autoinfection and retroinfection, the pathogen reinfects the same host, facilitating the pathogen to inhabit the same host indefinitely.