Swimmers Catch Severe Infections in the Baltic Sea

  Published: 26.09.07 Updated: 26.09.2007 15:50:34
I. Hökeberg. Department of Communicable Disease Control and Prevention, Stockholm County Council, Sweden

Septicaemia caused by non-toxigenic and non-agglutinating Vibrio cholera occurred in several elderly persons during the summer of 2006 in Sweden. All patients had been swimming in the Baltic Sea. Three cases were reported from Blekinge in the south of Sweden and two cases from Stockholm. One case of Vibrio vulnificus septicaemia was also reported from Stockholm. Two of the cases reported in Stockholm were elderly men with chronic ulcers and also other immunocompromising diseases. The third patient had a severe wound caused by a propeller from a motorboat. Accordingly, everyone had a wound as an entrance for the infection. Two of the three patients died due to septicaemia. They had all been infected in Sweden but just one in Stockholm County; the other two were infected in southern Sweden.

In 2004, the first serious case of Vibrio cholera (non-toxigenic, non- agglutinating) infection was notified in Stockholm County. The patient was a woman with multiple wounds on her lower limbs. She had been taking a bath in an outdoor wooden bathtub. The bathtub was filled with water from the Baltic Sea and heated to above 30° C. Vibrio cholera was found in the tub as well as in pipes connecting the tub with the sea water.

The non-toxigenic and non-agglutinating form of Vibrio cholera is present in the Baltic Sea but does not seem to cause serious disease in swimmers at water temperatures below 20° C. Sea temperatures above 20° C are seen along the Swedish Baltic coastline only during particularly warm summers. Vibrio cholera has also been found in Swedish lakes like Mälaren and Erken in the vicinity of Stockholm but no case of disease has been attributed to exposure in these lakes.

Vibrio vulnificus, however, as a cause of wound infection and septicaemia, is previously well described. Three cases of wound infection caused by Vibrio vulnificus after swimming in the Baltic Sea were reported from Germany during the summer of 2006.

Swedish health authorities issued recommendations during the summer. People with large, open wounds were advised to avoid swimming in bays and lakes in Sweden. People who are immunocompromised, by disease or old age, and have open wounds are at increased risk of developing wound infection and septicaemia and should take precautions. These recommendations may need to be repeated prior to the 2007 summer season. Increased vigilance in the health services in countries around the Baltic Sea is advised.

The non-toxigenic and and non-agglutinating type of Vibrio cholera is not contagious and should not be confused with toxin producing Vibrio cholera O1 or O139 that cause epidemic cholera. Cholera is found in several parts of the world but is no longer present in Sweden or other countries around the Baltic Sea.