Vibrio cholerae-An emerging pathogen in Austrian bathing waters?

Abstract

Vibrio cholerae, an important human pathogen, is naturally occurring in specific aquatic ecosystems. With very few exceptions, only the cholera-toxigenic strains belonging to the serogroups O1 and O139 are responsible for severe cholera outbreaks with epidemic or pandemic potential. All other nontoxigenic, non-O1/non-O139 V. cholerae (NTVC) strains may cause various other diseases, such as mild to severe infections of the ears, of the gastrointestinal and urinary tracts as well as wound and bloodstream infections. Older, immunocompromised people and patients with specific preconditions have an elevated risk. In recent years, worldwide reports demonstrated that NTVC infections are on the rise, caused amongst others by elevated water temperatures due to global warming.The aim of this review is to summarize the knowledge gained during the past two decades on V. cholerae infections and its occurrence in bathing waters in Austria, with a special focus on the lake Neusiedler See. We investigated whether NTVC infections have increased and which specific environmental conditions favor the occurrence of NTVC. We present an overview of state of the art methods that are currently available for clinical and environmental diagnostics. A preliminary public health risk assessment concerning NTVC infections related to the Neusiedler See was established. In order to raise awareness of healthcare professionals for NTVC infections, typical symptoms, possible treatment options and the antibiotic resistance status of Austrian NTVC isolates are discussed.

Keywords: Climate change; Diagnostic tools; Environmental reservoirs; Epidemiology; Vibrio cholerae non-O1/non-O139.

Fig. 1

Reported cases of non-toxigenic Vibrio cholerae (NTVC) infections in Austria, from 2006 to 2022 (n = 38). Dark blue bars represent cases with a confirmed travel history to local bathing waters. Medium blue bars represent cases where information is insufficient but there is a likely association with local bathing waters. The grey bars are cases of travel-associated NTVC infections

Fig. 2

Age distribution (a) and type of infection (b) of the 27 non-toxigenic Vibrio cholerae (NTVC) cases reported between 2006 and 2022 with Austrian and most likely Austrian origin. Additional information: Sex: 53% male, 26% female, 21% insufficient data; Age median = 32 years, min. = 4 years, max. = 80 years

Fig. 3

Typical appearance of non-toxigenic Vibrio cholerae (NTVC) on sheep-blood agar (a) and on thiosulfate citrate bile sucrose (TCBS) agar (b). Typical NTVC colonies on TCBS agar after filtration of 100 ml lake water sample through a 0.45 µm pore size nitrocellulose filter (c)

Fig. 4

Seasonal abundance of V. cholerae cells in water (blue bars) and on zooplankton (orange bars) at a representative sampling site of Lake Neusiedler See (data taken from Schauer et al. [42])