Environmental surveillance during an outbreak of tularaemia in hares, the Netherlands, 2015

Abstract

Tularaemia, a disease caused by the bacterium Francisella tularensis, is a re-emerging zoonosis in the Netherlands. After sporadic human and hare cases occurred in the period 2011 to 2014, a cluster of F. tularensis-infected hares was recognised in a region in the north of the Netherlands from February to May 2015. No human cases were identified, including after active case finding. Presence of F. tularensis was investigated in potential reservoirs and transmission routes, including common voles, arthropod vectors and surface waters. F. tularensis was not detected in common voles, mosquito larvae or adults, tabanids or ticks. However, the bacterium was detected in water and sediment samples collected in a limited geographical area where infected hares had also been found. These results demonstrate that water monitoring could provide valuable information regarding F. tularensis spread and persistence, and should be used in addition to disease surveillance in wildlife.

Tularemia transmission to humans: a multifaceted surveillance approach

“…In Hungary a hare (Lepus europaeus)-tick cycle explains their inter-epizootic period [22] and should be studied in Georgia. Contaminated water also is likely to serve as a reservoir [23][24][25][26].…”

Environmental Surveillance of Zoonotic Francisella tularensis in the Netherlands

“…Disease incidence due to infections with subspecies holarctica has been shown to be higher near lakes and rivers (Desvars et al, 2015 ). F. tularensis has been detected in various types of surface waters and sediments (Petersen et al, 2009 ; Broman et al, 2011 ; Janse et al, 2017 ) where the bacterium can be hosted by free-living protozoa and may reside in biofilms (Abd et al, 2003 ; Sinclair et al, 2008 ; van Hoek, 2013 ).…”

“…Since then, occasional human cases (17 in total) have been reported. Also, after surveillance of dead hares started in 2011 (Janse et al, 2017 ), several Francisella -infected hares were identified in the same period. These human and hare tularemia cases from 2011 to 2017 occurred dispersed in time and space (van de Wetering et al, 2015 ; Pijnacker et al, 2016 ; Janse et al, 2017 ; Zijlstra et al, 2017 ), which suggests a widespread occurrence and the existence of an endemic cycle of the pathogen.…”

“…Also, after surveillance of dead hares started in 2011 (Janse et al, 2017 ), several Francisella -infected hares were identified in the same period. These human and hare tularemia cases from 2011 to 2017 occurred dispersed in time and space (van de Wetering et al, 2015 ; Pijnacker et al, 2016 ; Janse et al, 2017 ; Zijlstra et al, 2017 ), which suggests a widespread occurrence and the existence of an endemic cycle of the pathogen. In 2015, environmental surveillance following a tularemia epizootic among hares in Friesland (northern Netherlands) revealed the presence of F. tularensis DNA in surface water and sediments (Janse et al, 2017 ).…”

“…These human and hare tularemia cases from 2011 to 2017 occurred dispersed in time and space (van de Wetering et al, 2015 ; Pijnacker et al, 2016 ; Janse et al, 2017 ; Zijlstra et al, 2017 ), which suggests a widespread occurrence and the existence of an endemic cycle of the pathogen. In 2015, environmental surveillance following a tularemia epizootic among hares in Friesland (northern Netherlands) revealed the presence of F. tularensis DNA in surface water and sediments (Janse et al, 2017 ). Surveillance data can be used to signal potential public health threats, but also to better understand the environmental components that may drive changes in the abundance of pathogenic microbes.…”