Baltic Sea · Vibrio vulnificus · bathing with wounds
Vibrio bacteria in the Baltic Sea
Vibrio bacteria occur naturally in the Baltic Sea – in warm, low-salt brackish water they multiply strongly in midsummer. For healthy bathers without open wounds this is harmless, and there is no general bathing ban. It becomes serious for certain risk groups: anyone with an open wound and a pre-existing condition should avoid warm seawater.
What are the conditions today?
Conditions favourable
The water is 20 °C or warmer – according to the state of Schleswig-Holstein, Vibrio vulnificus is activated from this mark. For risk groups with wounds that means: stay out of the water.
Water temperature: 20,8 °C
This is an assessment based on the measured water temperature – NOT a measurement of bacteria. The state does not routinely test bathing waters for vibrios, so the number of germs cannot be derived from it.
What does the EU model say for our bay?
The EU health agency ECDC calculates daily how favourable the environmental conditions for vibrios are – from water temperature and salinity. For the Bay of Lübeck it currently looks like this:
Index off the Trave estuary 5.73 / 30
0 in the lower part of the scale 30
Model date 17/08/2026
The index rates environmental conditions only. It is not a measured germ count and says nothing about an individual’s infection risk. A higher value means the bacteria find better conditions to multiply.
The value applies to the nearest model cell off the Trave estuary. Right at the beach the computation grid is land – the model returns no values there.
Data: ECDC Vibrio Map Viewer (model v2, Copernicus Marine Service) · CC BY 4.0
What are vibrios?
Vibrios are rod-shaped bacteria that occur naturally in saline water – long known as a normal component of the North and Baltic Seas. In Schleswig-Holstein three species relevant to humans are mainly detected: Vibrio vulnificus, Vibrio parahaemolyticus and Vibrio cholerae (not the cholera-causing types). They prefer shallow, quickly warmed water in the Baltic, the Schlei and river estuaries – brackish water with moderate salinity.
Why the Baltic Sea in particular?
Because two conditions come together here: warmth and little salt. Vibrios prefer a salinity well below that of the North Sea or Mediterranean – the low-salt Baltic matches that exactly. Add temperature: according to the German Federal Institute for Risk Assessment, vibrios multiply markedly from about 18 °C, with a particularly high risk from 20 °C. Shallow bays such as those off Travemünde warm into exactly this range in midsummer – the current water temperature is therefore the best indicator.
How do infections happen – and how not?
There are two routes: through wounds and through raw seafood. When bathing or wading, the bacteria can enter through even the smallest skin injuries; ear infections are also described. The second route is eating raw or insufficiently cooked seafood such as oysters, mussels, prawns or fish. Important: there is no person-to-person transmission, and swallowing seawater is not the typical route.
Who really needs to take care?
Not all bathers are equally affected. The state of Schleswig-Holstein names these groups in particular:
- People with open or poorly healing wounds – the decisive factor
- Older people with a weakened immune system
- People with liver disease
- People with diabetes mellitus
- People with alcohol dependency
- People with immunosuppressive conditions or therapies (such as cancer)
For healthy bathers without wounds: normal time in the water is considered harmless. A general bathing ban for the North and Baltic Seas is not indicated according to the state, because there is no danger to the general population.
How to protect yourself
- With open or poorly healing wounds, stay out of warm seawater – including wading. This applies especially with the pre-existing conditions listed above.
- Cover fresh wounds, even small cuts or scratched insect bites, before bathing – or postpone the swim.
- Do not eat seafood raw and cook it thoroughly – oysters, mussels, prawns and fish.
- Rinse and dry wounds well after bathing.
- Above 20 °C, decide more consciously: the shallow, heated shore zone is the warmest part.
Symptoms: how to recognise an infection
The time between contact and first symptoms is short – usually 12 to 72 hours. With a wound infection the site hurts strikingly badly, reddens and swells; the state describes that wound infections take a very serious course in more than half of cases, with deep skin and tissue destruction up to blood poisoning. After eating raw seafood, nausea, diarrhoea and cramps dominate, in severe cases also sepsis.
What to do if you suspect an infection
Seek medical help immediately – the course can be rapid. One sentence matters at the doctor’s: “I was swimming in the Baltic Sea.” Only then will they test specifically for vibrios. Detected early, the infections are treatable with antibiotics, even in at-risk patients. Doctors report suspected cases to the health authority under § 6 of the German Infection Protection Act. Addresses are on our page Doctors and pharmacies; in an emergency call 112.
Does “excellent bathing water quality” say anything about vibrios?
No – and that is the most common misconception. The official EU classification of Travemünde’s two bathing waters (Kurstrand and Priwall) is based on measuring E. coli and intestinal enterococci, i.e. faecal germs. Vibrios are not included: they are natural marine bacteria and are not routinely sampled as part of bathing water monitoring. An excellent rating therefore does not mean “no vibrios” – both statements stand side by side. More on water quality under Beach and water.
How widespread are vibrios in Schleswig-Holstein?
The state does not sample routinely but repeatedly runs research projects. In the 2025 project, two samples were taken at each of 36 bathing sites; vibrios were detected in 64 of the 72 samples, at concentrations between 1 and 120 CFU per millilitre. Above all this shows: the bacteria are a normal part of the water, and their detection alone is not an alarm signal. Whether concentrations rise long-term due to warmer seas cannot currently be derived from the data, according to the state – though it is considered possible.
ECDC Vibrio Map Viewer (modelled conditions in near real time) ↗
Frequently asked questions about vibrios
Can you still swim in Travemünde despite vibrios?
Yes. For healthy people without open wounds, bathing in the Baltic is considered harmless; a general bathing ban is not indicated according to the state of Schleswig-Holstein, because there is no danger to the general population. Caution applies to risk groups with wounds.
From what water temperature are vibrios active?
They multiply markedly from about 18 °C, and from 20 °C there is a particularly high risk according to the Federal Institute for Risk Assessment. The state of Schleswig-Holstein names the mark of around 20 °C at which Vibrio vulnificus is activated. They remain active for a while even when the temperature drops below that again.
How do you get infected with vibrios?
Through wounds while bathing or wading – even the smallest skin injuries suffice – and by eating raw or insufficiently cooked seafood such as oysters, mussels, prawns or fish. Ear infections are also described. Vibrios are not transmitted from person to person.
Who belongs to the risk group?
Above all people with open or poorly healing wounds, older people with a weakened immune system, and people with liver disease, diabetes mellitus, alcohol dependency or immunosuppressive conditions and therapies.
What are the symptoms of a vibrio infection?
Symptoms usually appear 12 to 72 hours after contact. With wound infections the site hurts strikingly badly, reddens and swells; severe courses with deep tissue damage up to blood poisoning are possible. After eating raw seafood, nausea, diarrhoea and cramps dominate.
What to do if a wound hurts after bathing?
Seek medical help immediately and explicitly mention that you were swimming in the Baltic Sea – only then will they test specifically for vibrios. Detected early, the infections are treatable with antibiotics. In an emergency call 112.
Is the bathing water in Travemünde tested for vibrios?
No, there is no routine sampling for vibrios. Official bathing water monitoring measures E. coli and intestinal enterococci. However, the state repeatedly runs research projects; in 2025 vibrios were detected in 64 of 72 samples at 36 bathing sites.
Does “excellent water quality” mean there are no vibrios?
No. The EU classification is based on faecal germs (E. coli, enterococci) and says nothing about vibrios, which are natural marine bacteria. Both statements can be true at the same time.
Are vibrios new to the Baltic Sea?
No. They have long been known as a natural component of the North and Baltic Seas. What is new is that warm summers more often favour the conditions for them to multiply; so far the state does not derive a robust trend of rising concentrations from its data.
Are children or dogs particularly at risk?
For healthy children the same rules apply as for adults: without open wounds bathing is harmless, fresh grazes are better covered or the swim postponed. The state makes no statement on pets – with open wounds on an animal, restraint is sensible; if in doubt ask a vet.
