Diphtheria outbreak in Germany – RKI warns of infectious disease

A dangerous infectious disease is on the rise. Anyone who notices a slight cough or an irritated throat should also consider diphtheria . The Robert Koch Institute (RKI) has identified a "signal of a nationwide diphtheria outbreak" in its latest report . The strain is "Corynebacterium diphtheriae of sequence type ST574."

This virus was first detected in Germany in autumn 2022. By the end of April 2025, the RKI had recorded 126 cases – most among refugees, but increasingly also among homeless or unvaccinated people, as well as among older people with pre-existing medical conditions.

In comparison to the diphtheria cases in recent years, it is striking that:

• other vulnerable population groups are now also affected, and no longer just refugees.
• There are increasing cases of diphtheria in the respiratory tract, some of which are severe or fatal .
• the transfers took place within Germany.

Based on these new findings, the Robert Koch Institute (RKI) wants to "raise awareness that diphtheria is occurring more frequently again, both in the form of primary diphtheria and respiratory diphtheria." Medical personnel and health authorities should be particularly vigilant. Laboratories should conduct additional testing for diphtheria in suspected cases and report positive cases.

There is an effective vaccination against diphtheria that protects against the disease – from sore throat, mild fever, shortness of breath, and choking. With diphtheria, the throat can swell so much that patients can't breathe. This is caused by the toxin of a bacterium called Corynebacterium, which is transmitted through droplets, for example, when sneezing.

"After two to five days, the diphtheria patient initially notices a sore throat and a slight fever. Later, hoarseness, shortness of breath, and swollen lymph nodes develop. Finally, a stubborn, grayish-whitish plaque forms on the tonsils and throat." This is how experts at the Munich Clinic describe the course of the disease. "Diphtheria can cause the throat to swell so much that suffocation is imminent. The toxin can also reach the heart, liver, or kidneys via the bloodstream, causing dangerous complications."

Anyone who is unvaccinated and becomes ill needs an antidote. Antibiotics also fight the pathogen.

Diphtheria is an acute infectious disease that can be fatal without treatment. In 1892, more than 50,000 mostly young people died from it in Germany, according to the Standing Committee on Vaccination (Stiko). Thanks to vaccination, which is now part of the standard vaccination program for infants, the number has declined dramatically.

The vaccination is recommended from three months of age. After three doses, a child is considered immune. The vaccination is usually administered as part of a six-in-one vaccination, which protects not only against diphtheria, but also against

• tetanus
• Polio (infantile paralysis)
• Pertussis (whooping cough)
• Haemophilus influenzae type b (Hib)
• Hepatitis B

However, current vaccination rates show that the willingness to vaccinate oneself or one's children is dwindling. For diphtheria, the complete immunization rate among children aged 15 months was recently only 64 percent. In 2024, almost 50 cases were reported to the Robert Koch Institute (RKI).

"A fundamental dilemma of vaccinations is that they prevent diseases that many people no longer recognize," Reinhard Berner, chairman of the German Standing Committee on Vaccination (Stiko), told the German Press Agency. One example is diphtheria, once called the "strangling angel of children." As Berner explains, its widespread disappearance has led to many people no longer knowing how painful and dangerous this and other diseases are.

The experts at the Munich Clinic also emphasize: “Doctors warn against vaccine fatigue because, thanks to vaccination, the disease has disappeared from the consciousness of the population in Germany, but diphtheria still poses a deadly threat.”