Two dead from Vibrio infections in Germany as Baltic Sea season starts early

Early season and rising case numbers

Germany's Robert Koch Institute (RKI) has registered 17 domestically acquired Vibrio infections so far in 2026, with the season beginning earlier than usual. The institute attributes the early start to high air temperatures that warmed coastal waters rapidly. Among the 17 cases, 10 are men and 7 are women, with ages ranging from 3 to 95 and a median age of 70. Berlin's State Office for Health and Social Affairs (Lageso) separately reports three cases in the capital this year, all in people over 75. By calendar week 29, Berlin had already matched or exceeded the full-year totals of recent years: five infections were recorded in both 2023 and 2024, and two in 2025. In previous years, an average of only one infection had been reported by that point in the calendar.

Fatalities and at-risk groups

The RKI confirms two deaths among the 17 nationwide cases, both involving very elderly individuals. One of those fatalities was recorded by Lageso: a person who had visited the Baltic Sea coast in Mecklenburg-Vorpommern fell ill on 22 June and died on 13 July. It is the first Vibrio-related death registered by the Berlin authority since 2023. All three Berlin patients had wound infections; in two cases the infection progressed to sepsis, one with a fatal outcome. Lageso did not disclose the gender of those affected, citing data protection rules, but stressed that everyone was over 75 and belonged to recognised risk groups. Those groups include older adults, immunocompromised people, and individuals with pre-existing conditions such as diabetes, liver disease or severe heart disease. Open wounds sharply increase the danger of infection.

Baltic Sea conditions

Vibrio bacteria occur naturally in fresh, brackish and salt water. When water temperatures exceed 20°C, they can multiply rapidly in surface waters, according to the RKI. The Baltic Sea is particularly susceptible because of its low salinity and shallow coastal areas that warm quickly. Mecklenburg-Vorpommern's State Office for Health and Social Affairs (Lagus) reports three Vibrio infections in the state this year up to calendar week 29. Over the past five years, Lagus has recorded 28 infections and four deaths linked to Vibrio in Mecklenburg-Vorpommern. The early warming this summer has compressed the typical season, raising concern among health officials.

Research and warning system

At Warnemünde beach, scientists from the Leibniz Institute for Baltic Sea Research (IOW) are developing a more precise warning tool. A drone collects data on water temperature, currents, salinity and blue-green algae blooms in the bathing zone. Artificial intelligence then evaluates the data, with the goal of producing a traffic-light-style Vibrio risk assessment within minutes of a drone flight. The system is still in development but could eventually give bathers and local authorities rapid, location-specific alerts.