Tularemia: History, Epidemiology, Pathogen Physiology, and Clinical Manifestations

Abstract

Francisella tularensis has been recognized as a human pathogen for almost 100 years and is the etiological agent of the zoonotic disease tularemia. Soon after its discovery, it became recognized as an important pathogen in several parts of the world, for example, in the United States and Soviet Union. The number of tularemia cases in the two countries peaked in the 1940s and has thereafter steadily declined. Despite this decline, there was still much interest in the pathogen in the 1950s and 1960s since it is highly infectious and transmissible by aerosol, rendering it a potent biothreat agent. In fact, it was one of the agents that was given the highest priority in the offensive programs of the United States and Soviet Union. After termination of the offensive programs in the 1960s, the interest in F. tularensis diminished significantly and little research was carried out for several decades. Outbreaks of tularemia during the last decade in Europe, for example, in Kosovo, Spain, and Scandinavia, led to a renewed public interest in the disease. This, together with a massive increase in the research funding, in particular in the United States since 2001, has resulted in a significant increase in the number of active Francisella researchers. This article summarizes, predominantly with a historical perspective, the epidemiology and clinical manifestations of tularemia and the physiology of F. tularensis.

Update on tick-borne bacterial diseases in Europe

“…None of the ticks tested positive for F. tularensis (Kaysser et al, 2008). In central European foci, hares appeared to be the main carrier and source of tularemia in humans, whereas ticks harbored by hares were the perennial reservoir of F. tularensis (Sjostedt, 2007b). Several outbreaks of tularemia have been reported in the literature, but they were not associated with transmission by ticks (Kantardjiev et al, 2006;Reintjes et al, 2002;Payne et al, 2005;Perez-Castrillon et al, 2001).…”

“…In Central Europe, contact with infected animals and ingestion of contaminated food or water are more common modes of transmission (Hubalek et al, 1996;Petersen et al, 2009). The prevalence of tularemia in ticks is very low: only 0.01 % of 120,000 I. ricinus adult ticks in Russia were positive (Sjostedt, 2007a). In Slovakia, 34 F. tularensis strains were isolated from 4,542 starving ticks, predominantly from D. reticulatus (Gurycova et al, 1995).…”

Epidemiology of Tularemia

“…Tularemia was first described as a disease of the rodent group called lemmings in the 16 th century in Norway. It was also described in Japan and Russia in the 1800s (11,12). The infectious agent was isolated by MacCoy and Chapin from dead ground squirrels in 1911 in Tulare, California, USA after the San Francisco earthquake in 1906.…”

“…Because ticks can carry the bacteria by both transovarial and transstadial transmission, they play a role in the life cycle of tularemia as both reservoir and vector.of its discovery (5). The first human cases were reported by Lamb and Wherry in 1914 (12). Edward Francis was the first person who studied the epidemiology of the disease in humans, and described the clinical manifestations in humans.…”

“…Especially amoebae living in water (Acanthamoeba Castellani) are important for the bacteria that survive in nature (50,61). Bacteria can survive for years in water, soil, mud, swamps, animal wastes, barns, and frozen meats (6,11,12,14).…”