Genomic analyses of Francisella tularensis strains confirm disease transmission from drinking water sources, Turkey, 2008, 2009 and 2012

Abstract

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Clinical Characteristics of Ulceroglandular Tularemia in Two Bulgarian Regions, 2014-2015: a Report of Five Cases

“…6 Similar data were reported by Turkish researchers. [17][18][19][20][21] In contrast French outbreak described glandular form in 46% and ulceroglandular tularemia in 26% of cases. 22 The variety of clinical forms is infl uenced by complex factors as transmission, mechanism of entry and infective dose.…”

A Single Mechanosensitive Channel ProtectsFrancisella tularensissubsp.holarcticafrom Hypoosmotic Shock and Promotes Survival in the Aquatic Environment

“…F. tularensis can only persist in fresh water for a limited time (27, 28), and is seasonally recovered from natural bodies of water, suggesting recurrent cycles of contamination (7, 31). Early soviet researchers reported that a single infected animal could contaminate 500,000L of water (44), and infected animals are indeed implicated in virtually all cases of water contamination with F. tularensis (6–8, 10–12, 16, 17, 19, 22, 26, 31–33). To survive an osmotic downshock, such as that encountered when going from a mammalian host to fresh water, bacteria rely on mechanosensitive channels which act as ‘pressure relief valves’.…”

“…Outbreaks of tularemia from contaminated drinking water have been reported in at least 10 countries, totaling thousands of cases. Such outbreaks have been reported in Turkey (6–8), Sweden (9), Germany 10), Norway 11–13), Russia (14, 15), Bulgaria (16, 17), Kosovo (18, 19), The Czech Republic(20), Italy (21, 22) and the Republic of Georgia (23). Isolated cases of tularemia associated with infection from fresh water have also been described in France (24, 25) and the USA (26).…”

“…Isolated cases of tularemia associated with infection from fresh water have also been described in France (24, 25) and the USA (26). In many of these cases, F. tularensis was detected by PCR (10–13, 20) or cultured (8, 9, 15–17, 23, 26) from water of the affected area.…”

“…Persistence may be enhanced by the presence of amoebae or ciliates (29, 30), but the bacterium is not able to persist in fresh water indefinitely (27, 28), and is often only seasonally recovered from natural bodies of water (7, 31). This suggests that F. tularensis is introduced to bodies of water shortly before outbreaks, and indeed almost all cases of water contamination are attributed to the carcasses or excreta of infected animals including hares, rodents, voles, lemmings, muskrats, and beavers (6–8, 10–12, 16, 17, 19, 22, 26, 31–33). The shift from an animal to a fresh water niche involves an abrupt decrease in extracellular osmolarity, producing a hypoosmotic shock (or ‘downshock’).…”