RKI warns of diphtheria outbreak: What is behind the disease?

The Robert Koch Institute (RKI) has warned of a Germany-wide diphtheria outbreak. In its current epidemiological bulletin, the RKI cites genome sequence analyses. Specifically, the pathogen is Corynebacterium diphtheriae of sequence type ST-574, which was first detected in Germany in autumn 2022.

Unlike previous cases, this one not only affects refugees, but also other vulnerable groups such as the homeless or elderly people with pre-existing medical conditions. It is also striking that the disease is being transmitted within Germany and that respiratory diphtheria, which affects the breathing process and is sometimes fatal, is increasing, according to the RKI. Furthermore, it cannot be ruled out that neighboring countries are also affected.

For a long time, diphtheria had virtually disappeared from Germany. In January, a schoolchild in Berlin died from it. According to the Tagesspiegel newspaper, he had not been vaccinated and had battled the disease for four months. How dangerous is diphtheria? What symptoms occur, and how can you protect yourself against it? An overview of the most important questions and answers.

According to the Robert Koch Institute (RKI), diphtheria is a bacterial infection that can occur both in the throat and on the skin.

For a long time, the disease was one of the leading causes of illness and death among children. However, it can occur at any age. Even though the disease is potentially fatal, deaths have become very rare in Germany.

Pharyngeal and laryngeal diphtheria is usually caused by Corynebacterium diphtheriae. The bacterial strains C. diphtheriae, C. ulcerans, and C. pseudotuberculosis can cause so-called cutaneous diphtheria.

After two to five days, those affected typically develop a sore throat and "firmly adherent plaque" in the throat. The boy who has now died was initially treated for acute tonsillitis in September. Diphtheria was later diagnosed. Since October, the child has required artificial respiration.

The plaque in the throat area can accumulate and cause suffocation. This is why diphtheria has been nicknamed the "choking angel" for children.

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According to the Techniker Krankenkasse, other symptoms can include a sweet, foul breath odor, swollen lymph nodes, a barking cough, hoarseness, and fever.

If diphtheria pathogens enter a wound, a greasy coating can form. Ulcers, suppuration, and pain can also occur. This is known as cutaneous diphtheria. If pathogens enter the bloodstream, internal organs and nerves can also be damaged. The Robert Koch Institute (RKI) warns of inflammation of the heart muscle or nerves.

In the most common form of diphtheria, pharyngeal diphtheria, a thick, whitish, and firmly adherent coating forms in the throat and nose after a few days. This layer is also called a pseudomembrane.

According to the MSD manual, it consists of white blood cells, bacteria, and other substances. The further it spreads into the throat, the more it narrows the airways and makes swallowing difficult.

Diphtheria is highly contagious. The disease is caused by corynebacteria and is transmitted primarily through droplet infection. The pathogens are spread from person to person through close contact, for example, when coughing or sneezing.

However, direct transmission through objects or smear infection via skin diphtheria wounds or infectious secretions is also possible.

The most effective protection against diphtheria is vaccination. Therefore, the German Standing Committee on Vaccination (Stiko) recommends that infants, children, adolescents, and adults be vaccinated against the disease as a matter of routine.

Infants should receive a basic vaccination at two, four, and eleven months of age. Children should receive a booster vaccination once between five and six years of age and once between nine and 14 years of age. From age 18, the Stiko recommends a booster vaccination every ten years.

Those who have not yet been vaccinated against diphtheria can get immunized. This involves two vaccinations one month apart and a third vaccination six months later.

Vaccination provides reliable protection against the symptoms of diphtheria, i.e., against the onset of the disease, but not against infection. This means that even vaccinated people can be carriers of the diphtheria-causing corynebacteria.

Diphtheria is highly contagious and can be fatal. Upon inquiry, the Robert Koch Institute (RKI) reported that one adult died from cutaneous diphtheria in 2023, and two adults died from pharyngeal diphtheria in 2024. However, because most people in Germany are vaccinated, such severe cases are rare.

According to the Robert Koch Institute (RKI), 77 percent of children born in 2021 are fully vaccinated by the age of 20 months. The vaccination rate is higher among school beginners, at 92.4 percent (2020) .

The current case in Berlin also demonstrates how crucial vaccination is for the course of the disease. Through contact tracing by the health department, another person in the child's family was diagnosed with diphtheria. However, this person had been vaccinated and therefore only experienced a mild course of the disease, according to the Havelland district.

The sooner, the better. Because if the disease is detected early, there's a good chance of full recovery. If suspected, the treating physician will administer an antidote and an antibiotic to kill any remaining bacteria.

Diphtheria is usually treated in a hospital. This allows patients to receive rapid intensive care in the event of complications. Because the disease is so contagious, patients are isolated from other people. In the worst cases, patients may require artificial respiration.

Since most infants and children in Germany have been vaccinated since 1960, the disease has become rare in this country.

Because the disease cannot be completely eradicated through vaccination, smaller outbreaks continue to occur. However, according to Statista, the annual number of cases has been in the single to low double digits for more than twenty years.

There was a sudden increase in 2022. 177 cases of diphtheria were reported. The following year, the number was 145. Since last year, however, the numbers have returned to normal, with 47 cases.

The RKI attributes the sudden increase in the Infectious Disease Epidemiological Yearbook to imported pathogens that affected several countries in Europe in the summer of 2022.

This text has been updated. It was first published on February 2, 2025.