Legionnaires' disease

Synonyms

Legionellosis, Pontiac fever (milder course)

definition

The Legionnaires' disease is the result of infection with Legionella pneumophila, an aerobic (with oxygen) living, gram-negative rod-shaped bacterium, which in large warm water systems has its disease significance for humans.

Epidemiology / frequency distribution

In Germany there is about 400 cases of illness. In the USA, where Legionnaires' disease was first described, it is estimated that 90,000 diseases per year. In healthy people, about 20% of the disease is fatal, while in patients with weakness of the Immune system 70% can be fatal. The Pontiac fever is not fatal.

history

After 1976, at the annual meeting of members of a US war veterans association in a hotel in Philadelphia, 180 cases of serious disease lung infection came, from which almost 30 people died, investigations were made into the cause of the disease, which was followed by the discovery of the hitherto unknown bacterium Legionella pneumophila followed. The naming "Legionnaires' disease“Occurred because mostly US veterans, but also a few other hotel guests were affected.

The milder one Pontiac fever has already been described after an outbreak in the city of Pontiac in 1968, without a pathogen being detected at the time.

causes

Legionella pneumophila/ Legionnaires' disease is a germ that occurs everywhere in the environment in soil and water, which finds favorable living conditions in warm, stagnant water. In this context, poorly used hot water systems in larger buildings, air conditioning systems, but also air humidifiers, which can cause an infectious aerosol to develop, which is typical for Legionnaires’s disease, the pneumonia of the supporting and intermediate tissues (interstitial / atypical pneumonia) responsible for. For larger buildings such as Even hospitals, mechanisms are created to disinfect the hot water, such as by heating the system in sections to over 70 ° C for a few minutes, by chemical additives such as chlorine, filter systems or by ultraviolet light.

Symptoms

To 2 to 10 days of incubation flu-like symptoms appear quickly (see flu), such as muscle pain, fever of sometimes over 40 ° C, chills and a headache. A dry to slightly bloody one to cough, Nausea, Vomit and diarrhea occur. If the brain is inflamed at the same time, impaired consciousness can also be expected.

In the case of Pontiac fever, the pure flu-like symptoms are in the foreground, but it does not occur lung infection. The symptoms appear after one or two days and last about a week.

diagnosis

As a non-common disease, the Legionnaires' disease partly a diagnostic challenge. The history of risk factors, such as the recent use of rarely used showers or air conditioning systems in older large buildings, is groundbreaking, but whirlpools, indoor fountains and aquariums are also possible sources of infection. In addition to the unspecific, flu-like symptoms is the interstitial pneumonia, which by a X-ray can be determined, an indication that further narrows the circle of causes of the disease. The creation of a blood culture is not successful, but Legionella can be detected directly in the sputum by means of a fluorescent antibody marker, or after cultivation on a special culture medium. However, since not all patients have sputum, a sample would need to be rinsed lung be taken. Alternatively, Legionella antibodies can be searched for in the urine, or the Legionella genome can be detected from blood, urine or sputum using the polymerase chain reaction, the detection from sputum being the most meaningful. Legionnaires' disease must be reported if it is proven.

therapy

With Antibiotics Legionnaires' disease is easy to treat. Come to use Quinolones or Macrolides. In severe cases, a quinolone can be combined with a macrolide, or a macrolide with rifampicin for two to three weeks.

prophylaxis

A vaccination against Legionella pneumophila there is not any. The risk of infection in modern, large European buildings is unlikely due to the disinfection systems, even if, for example, a shower that has not been used for a long time or the already mentioned whirlpool can pose a health risk with insufficient water hygiene, but not only on the germ Legionella pneumophila limited. In countries with lower hygiene standards, to reduce the risk of illness in a hotel complex, the hot water in the shower can run for five to ten minutes, during which the room must be left to avoid potentially infectious Aerosol inhale.

Particularly vulnerable people with a reduced immune system, such as the elderly, AIDS sufferers, otherwise immunosuppressed such as Chemotherapy patients, as well as patients with chronic lung disease, have an increased risk of exposure to Legionella, the full picture of Legionnaires' disease instead of the milder one Pontiac fever to develop. This group of people should avoid places where there is a risk of infection.

forecast

With timely suspicion and timely administration of Antibiotics the prognosis for Legionnaires' disease is favorable. If the immune system is severely impaired, however, the disease does not lose its dangerousness and remains potentially fatal. The course of Pontiac fever is similar to a flu-like infection.