RKI Confirms Growing Diphtheria Outbreak Across Germany

Health authorities in Germany are sounding the alarm after a sharp rise in diphtheria cases was recorded across multiple regions. The Robert Koch Institute (RKI), Germany’s central disease control body, has confirmed that the country is facing a nationwide outbreak of the bacterial infection, with the highest concentrations currently identified in Frankfurt, Berlin, and other metropolitan areas.

According to recent data published in the RKI’s Epidemiologisches Bulletin, 126 confirmed infections with the bacterial strain Corynebacterium diphtheriae — specifically sequence type ST574 — were registered in Germany by the end of April 2025. The strain, first detected in the country in autumn 2022, has now become a growing concern for public health officials. Genetic analysis shows increasing transmission within Germany itself, suggesting the outbreak is no longer confined to isolated incidents or imported cases.

Outbreak Expands Beyond Refugee Shelters

Although many of the early cases were concentrated among asylum seekers, particularly in shared housing facilities, recent clusters have been identified in broader segments of the population. Frankfurt has seen a surge in skin diphtheria cases, primarily but not exclusively affecting unhoused individuals. Another cluster includes respiratory cases in Berlin and other regions, including among native-born Germans.

The RKI reports that the current outbreak shows a significant shift: autochthonous transmission — meaning spread within Germany — is now more common. Vulnerable populations remain at greatest risk. These include refugees, people without permanent housing, those struggling with substance use, individuals who are unvaccinated, as well as the elderly and people with chronic health conditions.

Health professionals are urged to maintain a heightened level of awareness. Medical personnel have been advised to carefully assess patients with possible symptoms and to verify their vaccination status. Laboratories are also encouraged to perform specific toxin testing on suspected cases and promptly report confirmed infections to public health offices.

A Disease Thought Controlled Makes a Comeback

Once known as the “strangling angel” of children, diphtheria is a serious bacterial infection that can affect the throat, respiratory system, and skin. The primary transmission route is via airborne droplets, particularly through coughing or sneezing, although skin contact and contaminated surfaces can also spread the disease.

Typical symptoms of respiratory diphtheria include sore throat, fever, and swollen lymph nodes. In more severe cases, grayish-white patches may appear in the throat, which can lead to breathing difficulties. Skin diphtheria presents as chronic wounds or ulcers, especially in areas with poor hygiene.

Without timely treatment, the infection can become life-threatening. The diphtheria toxin may travel through the bloodstream and damage organs such as the heart, liver, and kidneys. Nerve paralysis and multiple organ failure are among the potential complications in untreated cases. Several recent reports have confirmed that respiratory diphtheria has caused fatal outcomes during the current outbreak.

Immunity Gaps and Waning Vaccination Coverage

Despite the resurgence of the disease, diphtheria remains preventable. In Germany, it is part of the routine immunization schedule. However, vaccination rates are increasingly inconsistent, especially among adults. Immunity wanes over time, and many individuals are unaware that booster shots are required every ten years to maintain protection.

The RKI emphasizes the importance of checking one’s vaccination record. People who have never received a complete series of diphtheria vaccinations are strongly advised to complete the full three-dose basic immunization. Children in Germany typically receive their first shots at two, four, and eleven months of age, followed by boosters at 5–6 and again between 9–16 years. For adults, the booster is commonly administered in combination with tetanus and pertussis vaccines.

Travelers planning to visit regions where diphtheria remains endemic — such as parts of Africa, the South Pacific, or Eastern Europe — are also advised to ensure their vaccination is up to date before departure.

RKI Calls for Nationwide Prevention Strategy

With confirmed cases rising each year — from 55 in 2022 to 49 in 2023, 18 in 2024, and at least four already in the first quarter of 2025 — the RKI warns that these numbers could increase without urgent preventative action.

Health authorities are now calling for stronger cooperation between clinics, local health departments, and shelters. Contact tracing, immediate isolation of suspected cases, and mass vaccination campaigns in high-risk environments are among the recommendations issued.

The growing number of severe and fatal respiratory cases, particularly among unvaccinated and immunocompromised individuals, highlights the urgency of reinforcing public awareness. In addition to alerting medical professionals, the RKI aims to inform the general population about the need for vaccination and prompt medical attention when symptoms occur.

As Germany deals with this unexpected reemergence of a disease once considered under control, public health experts are urging citizens to view the current situation as a serious but manageable challenge — one where individual responsibility plays a crucial role in preventing further spread.