Water-related bacteria on the rise in Sweden – can be fatal
Vibrio bacteria have become increasingly common in Swedish waters. However, it is not yet known exactly how common they are or where they are found. Sweden lacks an overall picture of where they are found and who is at risk of becoming seriously ill from them, says researcher Betty Collin.
Infections caused by Vibrio bacteria are often associated with swimming in countries around the Mediterranean – and that is a misconception, according to Betty Collin, senior lecturer in microbiology at Kristianstad University and a nurse in the infectious diseases department at Skåne University Hospital.
She has been researching Vibrio bacteria for 20 years and says that there are risks associated with swimming in Sweden too.
The bacteria are found in salt or brackish water in the Öresund and along the southern Baltic Sea coast.
But we don’t know how far north they have spread, and we don’t know what the situation is like on the west coast. We need to study this more closely, says Betty Collin.
Can lead to sepsis
If you become infected, you can develop swimmer’s fever, which in the worst-case scenario can lead to sepsis.
We have had patients who have developed severe sepsis and who have had limbs amputated. Unfortunately, fatalities do occur. For those who become infected, the suffering can be immense. Often, patients have to spend a long time in hospital.
Some patients have had large wounds whilst swimming, whilst others have had smaller ones. This is how Vibrio bacteria enter the body.
The risk of falling ill is greater if you also have underlying health conditions and a weakened immune system. It is usually older people who are affected. But we need to learn more about the risks, says Betty Collin.
Algal blooms increase the risk
Swimming during algal blooms is particularly risky.
Warm water above 20 degrees, combined with algal blooms, leads to higher concentrations of bacteria.
Another problem is that Vibrio bacteria are relatively new in Sweden, even amongst doctors.
They are not familiar with the bacteria or the mechanisms of antibiotic resistance they carry, which is crucial for administering the correct treatment quickly, says Betty Collin.
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There are several species of Vibrio bacteria that can cause wound fever.
The bacteria found in Sweden are Vibrio vulnificus, which can cause serious wound infections; Vibrio parahaemolyticus, which can cause intestinal and wound infections; and Vibrio cholerae, which can lead to tissue necrosis and sepsis.
The bacteria occur naturally in the sea. When their numbers become very high – for example, during algal blooms – there is a greater risk of coming into contact with them.
To date, the bacteria have not been found in Swedish inland lakes or freshwater lakes.
Vibrio infections peak in late summer. Many people fall ill in August or September.
The highest number of cases has been reported from Blekinge, Skåne, Kalmar, Halland, Gotland and Västra Götaland.
During hot summers such as 2006 and 2018, several severe wound infections and cases of sepsis were documented in Sweden.
