Howard Taylor Ricketts

Howard Taylor Ricketts (February 9, 1871 – May 3, 1910) was an American pathologist after whom the Rickettsiaceae family and the Rickettsiales are named.

He was born in Findlay, Ohio. In the early part of his career, Ricketts undertook research at Northwestern University on blastomycosis. He later worked in the Bitterroot Valley of Montana and at the University of Chicago on Rocky Mountain spotted fever. This early pathology, entomology and epidemiology research in Hamilton, Montana lead to the eventual formation of the Rocky Mountain Laboratory there.

While in Montana, Ricketts and his assistant discovered that the vector that carried the pathogen for Rocky Mountain spotted fever is a tick, the Rocky Mountain wood tick (some other species of ticks, such as the American dog tick also are vectors). It was not at once clear what kind of organism the pathogen was; eventually it was named Rickettsia, the first of the Rickettsiales to be identified. However, for decades, until electron microscopy and other technologies became sufficiently advanced, it was not known whether Rickettsiales were bacteria, viruses, or something in between. They now are known to be bacteria specialised for intracellular parasitism.