A scientist observes that all people who contract a painful skin rash known as shingles have previously in their lifetime been infected with chicken pox. He theorizes that the virus that causes chicken pox is the same virus that cause shingles. What type of reasoning is being displayed in this case?

The virus that generates chickenpox disease is a virus of the family called "herpes" where once they infect the human organism they are not eliminated by human defense, but are reserved and coexist in the organism in the lymph nodes, and when faced with immunodeficiency situations for certain reasons, it generates their reactivation, manifesting a recurrence of the disease.

Explanation:

The chickenpox virus is called the Zoster chickenpox virus, once it infects the human in his childhood, it settles in the ganglion near where it is inactively inoculated.

This is reactivated again manifesting shingles or herpes zoster in adulthood and in situations of immunodeficiency as in those malnourished humans, or who are exposed to long hours in the sun, or who suffer stressful situations.

Shingles is a disease that manifests itself in a very painful way (more than chickenpox) in the form of scabs and vesicles in different possible areas.