The Genus Francisella

Abstract

Francisella tularensis was recognized as the causative agent of a febrile illness in three different parts of the world in the early part of the 20th century. McCoy (1911) described a new disease which he found while studying a suspected outbreak of plague in ground squirrels in Tulare County, California. McCoy and Chapin (1912) isolated the etiologic agent of this “plague-like disease” and named the organism Bacterium tularense after the county in which it was found. This organism was also recognized as a disease agent of humans at about the same time. Pearse (1911) described what was known as “deer fly fever” in the area around Brigham City, UT, and Wherry and Lamb (1914) identified B. tularense as the infectious agent of a diseased meat worker in Cincinnati, OH. Edward Francis carried out an extensive series of experiments on the transmission of this organism and on the pathology of the disease he named tularemia (Francis, 1923). Shortly after the description of tularemia in the United States, Ohara (1925) isolated a similar organism (Francis and Moore, 1926) in Japan that caused Yato-byo (hare disease). In 1926, Soviet researchers (Pollitzer, 1967) isolated the same organism from human cases in Siberia. The name of the etiological agent of tularemia has changed over the years from B. tularense, to Pasteurella tularensis, to what it is called today, Francisella tularensis, the latter name in honor of the studies performed with this organism by Francis. In 1950 (Larson et al., 1955), another bacterium was discovered that was eventually placed in the genus Francisella. This organism, F novicida,has only been found twice since its original isolation and apparently has a very low infectivity for humans.