Cholera: Non-Cholera Vibrios
Vibrio cholerae non O1 und non O139
In addition to the toxin-producing Vibrio cholerae strains O1 and O139, the cholera pathogens, 200 other non-toxin-producing serogroups(Vibrio cholerae non O1 and non O139) are known. They lack the ability to produce the cholera toxin. In order to clearly distinguish them from the cholera pathogens, they are therefore grouped together under the term non-cholera vibrios. Non-cholera vibrios can also cause diseases, but these are usually less severe than cholera.
Non-Cholera vibrios are mainly found in bodies of water. Some species are considered salt-dependent, i.e. they are found particularly in seawater, lagoons, brackish water (mixture of salt and fresh water, e.g. in river estuaries) and in some cases also in inland lakes that have an increased salt content. They multiply more strongly at water temperatures above 20 °C.
Non-Cholera vibrios can cause diarrhoea, wound infections, otitis media, inflammation of the skin sub-tissues and subsequently blood poisoning. According to medical literature, typical risk groups include elderly and immunocompromised persons. People with pre-existing conditions such as liver disease, diabetes mellitus, cancer/chemotherapy and severe heart disease have an increased risk of contracting an infection and becoming seriously ill.
The increased occurrence of non-cholera vibrios in Austrian lakes may be related to the extreme heat period and the exceptional lack of precipitation in summer 2015: During additional investigations by AGES in summer 2015, non-Cholera vibrios were detected in a further seven freshwater bodies in Lower Austria and Burgenland. Migratory birds and waterfowl are considered a possible source of introduction. Among the positive detections of non-cholera vibrios, the classical indicator bacteria enterococci and E. coli, which are routinely used as indicators of increased risk in EU bathing water monitoring, were not elevated. The EU bathing waters investigated thus also complied with the legal requirements. The Federal Ministry of Social Affairs, Health, Long-Term Care and Consumer Protection (BMSGPK) commissioned a scientific assessment of this topic, which is rather new for Austria, from the European Centre for Disease Prevention and Control (ECDC). Periods of heat and thus the warming of waters may occur more frequently in the future as a result of global warming. This will also increase the likelihood of the occurrence of non-cholera vibrios in water bodies. Until now, only the East Sea was considered an area of increased possible occurrence. The ECDC has set up a monitoring system for the Baltic region that calculates and predicts the likely occurrence of non-Cholera vibrios using water temperatures in the Baltic Sea.