Vibrio vulnificus in Denmark

1. Introduction

Vibrio vulnificus, a halophilic marine vibrio, is an opportunistic human pathogen that can cause severe wound infections and septicemias with mortalities as high as 60 % (Oliver, 1989; Hlady & Klontz, 1996). The first fatal V. vulnificus infection was possibly reported in the 5th century B.C. by Hippocrates (Baethge & West, 1988). The king of the island Thasos in the Agean Sea got an acute infection which was characterized by a swollen foot with red and black skin lesions, rapidly progressive septicemia, and death on the second day. It is suggested that this infection was caused by V. vulnificus (Baethge & West, 1988).

In this century, most V. vulnificus infections have been reported from the United States, Japan, and Taiwan and since 1979 a number of cases in Belgium, Denmark, Germany, Holland, Israel, Korea, and Sweden, have been published (Mertens et al., 1979; Yang et al., 1991; Veenstra et al., 1992; Shin et al., 1993; Hoyer et al., 1995; Melhus et al., 1995; Dalsgaard et al., 1996b; Bisharat & Raz, 1997).

V. vulnificus in Denmark

During the unusually warm summer in Denmark in 1994, coastal water temperatures exceeded 20°C for about four weeks (Dalsgaard et al., 1996b). At the end of August 1994, 11 patients were admitted to hospitals with V. vulnificus infections; this was the first report of a series of human V. vulnificus infections from a temperate zone (Dalsgaard et al., 1996b). All patients contracted their disease after exposure to coastal water; none had consumed any seafood. In 1995 and 1997, a total of 3 and 4 V. vulnificus infections, respectively, were reported in Denmark (Bruun, 1997). In 1996 and 1998, water temperatures were low and no cases were reported (Bruun, 1997). The clinical cases in 1994 prompted the Royal Veterinary and Agricultural Univer sity, The Danish Institute for Fisheries Research, The Environmental Protection Agency and the Ministry of Food, Agriculture, and Fisheries to fund studies on the occurrence of V. vulnificus in Danish costal waters.

V. vulnificus is furthermore also pathogenic to eels and the expanding Danish eel-farming industry recently experienced severe outbreaks of V. vulnificus infections causing significant economic losses (Dalsgaard et al., in press). The use of brackish water in eel farms leads to higher growth potentials and thereby increased profits compared to the use of fresh water. However, water with low salinity of approximately 1% NaCl favors growth of V. vulnificus in eel farms where water temperatures usually are 23-24°C.