Legionellosis, which is also known as Legionnaires’ disease, is a severe variation of pneumonia. Legionnaires’ disease is caused by a bacterium that belongs to the subgenus Legionella.
What is legionnaires’ disease?
Legionnaires’ disease is a severe infection in the lungs caused by the bacterium Legionella pneumophila. Symptoms are similar to pneumonia and are characterized by high fever, difficulty breathing, and cough. Treatment with antibiotics is required. It occurs worldwide at any time of year, but is particularly common in summer and fall. It is usually not recognized until a late stage, as it can easily be mistaken for classic pneumonia. In some countries of the world, the disease is notifiable. Estimates suggest that about six percent of all pneumonias are caused by the bacterium Legionella pneumophila. Pontiac fever represents a weak variant of Legionnaires’ disease.
Causes
Legionnaires’ disease is a bacterial infection caused by Legionella pneumophila. These bacteria prefer fresh water that has a temperature between 20°C and 55°C. If the temperature exceeds 60°C, the germs die. For an infection with Legionella pneumophila, the germ must be inhaled and enter the lungs via the nose or mouth. Thus, possible sources of infection are the shower, whirlpools, air conditioners, inhalers as well as humidifiers. In this context, it should be mentioned that the Legionella pneumophila bacterium can usually spread in the water pipes if the pipes are hardly used. If the warm water stands in the water pipe for a long time, it provides an ideal medium for the germs to spread. Thus, Legionnaires’ disease can spread even in German gymnasiums if the showers have not been used for a long time during the summer vacations. Direct transmission of the pathogen from an infected person to a healthy person is unknown. Once in the lungs, the germs multiply in the monocytes, which are a special form of white blood cells. It can take up to ten days for Legionnaires’ disease to break out.
Symptoms, complaints, and signs
Legionnaires’ disease can cause a wide variety of symptoms. This depends on the amount and type of Legionella as well as the other condition of the affected person. Immunocompromised individuals, children, and the elderly are generally more susceptible to Legionnaires’ disease symptoms. In any case, the symptoms can be classified as threatening, but easily treatable. After a short incubation period of about two to ten days, a sudden and severe course of the disease occurs. The symptoms can vary greatly, but are usually reminiscent of influenza. There is a very high fever, sometimes over 40 degrees, chills, muscle pain and general malaise. In addition, there is pain or an uncomfortable feeling in the chest area. Signs of the lung infection that occurs are the dry cough] as well as the pain. In the further course, there is coughing with sputum, and here blood may also be admixed. Accordingly, the pneumonia expands and shortness of breath, circulatory problems, nausea and vomiting occur. Furthermore, due to the physical stress, neurological deficits may occur (temporary loss of consciousness, movement problems, etc.). The older and overall weaker the affected person is, the more severe the symptoms are. If no treatment is started, legionellosis is also classified as life-threatening.
Diagnosis and course
Diagnosis for Legionnaires’ disease is made by detecting the pathogen using a urine sample. The urine is analyzed for certain proteins that are present only in Legionella infection. Furthermore, a sample from the lungs or throat can provide information about an infection. If the diagnosis is made early, the disease takes an unproblematic course. If it is not detected and remains untreated, it can be fatal in people with immunodeficiency as well as elderly persons with a 20% probability. If the bacteria have only caused Pontiac fever, those affected will recover within five days even without medical attention. Once Legionnaires’ disease is overcome, there is no immunity to the Legionella bacterium.Thus, these patients may again contract Legionnaires’ disease.
Complications
Complications occur primarily in cases of severe legionellosis. Invasion of the pathogens through the respiratory tract can lead to a lung abscess, a pus-filled necrotic (dead) area in the lungs. This requires medical treatment. If the abscess does not heal completely, a drain must be surgically placed or the focus is removed. Furthermore, pleural effusions occur, whereby the amount of fluid in the sliding gap between the lung and the pleura increases and leads to difficult breathing. If an effusion does not completely regress, adhesions may form, limiting respiratory function. In the most severe cases, the bacteria of legionellosis cause respiratory insufficiency. In this case, external respiration becomes so weak that lung function almost succumbs. This requires immediate mechanical respiratory support. The pathogens often settle on the heart muscle (myocardium) or the pericardium when the heart is overworked during the disease. This leads to inflammation of the respective tissues. Another serious complication that the Legionnaires’ disease bacterium can cause is acute kidney failure. In this case, the function of the kidneys is suddenly impaired and urine excretion is reduced or almost completely extinguished. If suspected, immediate hospitalization is required. If left untreated, the mortality rate of legionellosis is five to ten percent.
When should you go to the doctor?
If a high fever, dry cough and other signs of Legionnaires’ disease are noticed, a doctor should be consulted. Other warning signs that need to be clarified include rhinitis, limb and muscle pain, and symptoms of pleurisy or laryngitis. Gastrointestinal symptoms such as nausea, vomiting and diarrhea are also characteristic of the disease. In some patients, encephalitis develops, which is manifested by dullness and confusion, among other symptoms. If these signs of illness occur, medical advice must be sought or, in the case of encephalitis, the affected person must be taken to the hospital. Weak breathing or kidney failure are serious complications that must also be clarified immediately. If urination is disturbed, it is best to consult the family doctor. People who regularly come into contact with contaminated water at work are particularly susceptible to Legionnaires’ disease. Small children and old or weakened people also belong to the risk groups and should have the described symptoms clarified immediately. In addition to the general practitioner, the internist, an ENT specialist or a pulmonary specialist can be consulted.
Treatment and therapy
Legionnaires’ disease or legionellosis should be treated by a physician as early as possible. Ideally, therapy should begin as soon as the bacterial infection is suspected. An antibiotic is prescribed for a period of 14 days. This inhibits the growth of the bacteria and kills the pathogens. Since the Legionella bacterium is very resistant, the right choice of antibiotic is crucial. Drugs containing the active ingredient erythromycin have proven to be particularly successful. Furthermore, it may be useful to take other medications for symptom treatment. People whose immune system is particularly weakened should take the medication for at least three weeks. The strength of the antibiotic is determined by the severity and course of the Legionnaires’ disease. In particularly severe courses of the disease, a combination of antibiotics can also be used. This is often given as an infusion during the first days of treatment. If there is only pontiac fever due to infection with the Legionella bacterium, treatment with an antibiotic is not necessary. Usually, only medication for symptom control is prescribed. Compared to common pneumonia, penicillin does not help kill the Legionella bacterium and thus is not used to treat Legionnaires’ disease.
Outlook and prognosis
Disease is possible worldwide. Legionnaires’ disease also occurs in industrialized countries. In most cases, the hot water supply system is responsible for this. In this, the health-threatening bacteria accumulate. The typical symptoms are often not correctly attributed. Doctors therefore assume that the number of unreported cases is high.Legionnaires’ disease usually takes a good course in previously healthy people. According to scientific surveys, only a fraction of those who contract the disease die. Many of them even do not notice any symptoms. The prognosis is different for older people over the age of 50 and those with weak immune systems. Experts believe that the risk is considerably higher for them. More than two-thirds of those with pre-existing heart or lung conditions die if infected. Antibiotics are available as a therapeutic agent. This works well, which means a favorable prognosis if treatment is started in time. An illness lasts only a few days. No symptoms remain. Antibodies can be detected in the blood. However, these disappear after a short time. This makes a new infection possible. An immunity does not build up.
Prevention
Preventive measures against legionnaires’ disease or legionellosis focus on avoiding the possible routes of infection. For example, when staying in a hotel, it is recommended that the hot water be drained for a few minutes. During this time, the bath should be left so as not to inhale the first water vapor. Most bacteria hide in it. Public hot tubs should be avoided. At home, hot water systems and air conditioning should be professionally installed and constantly maintained. Inhalers and humidifiers must be constantly disinfected and cleaned to prevent Legionnaires’ disease.
Aftercare
The type of aftercare depends on the course of the Legionnaires’ disease. In most cases, the disease heals completely. Then no symptoms remain. Scheduled examinations are not considered because no further consequences are expected from the original disease. However, preventive measures are suitable for aftercare. The physician provides any information as part of the therapy. Patients should be aware of possible infestation in hot water systems and take appropriate protective measures. The responsibility for implementing the physician’s advice falls on the sufferer. Legionnaires’ disease can also take a severe or even fatal course. If the patient survives such an illness, consequential damage such as impaired lung function sometimes remains. Aftercare then provides ways and means of spending a symptom-free everyday life. Depending on the extent of the symptoms, therapies and doctor’s appointments are necessary. A rhythm is agreed between doctor and patient. Drug treatment is not uncommon. Basically, immunocompromised persons are much more susceptible to disease. In addition, the risk of protracted symptoms is significantly increased in them. Their follow-up care is comparatively intensive due to their existing pre-existing conditions. Complications can be fatal in them.
What you can do yourself
In a healthy person with an intact immune system, an infection with the bacterial strain Legionella often leads to only mild symptoms. This can manifest itself, for example, in fever (Pontiac fever) and usually does not need to be treated. In most cases, the infection heals on its own. Until the fever has subsided, you should take it easy on yourself. However, if Legionella causes pneumonia in a patient, treatment must be started as soon as possible, as the infection can be life-threatening for the chronically ill and elderly. Consultation with a physician is essential in this case. Antibiotic therapy should be started as soon as possible, since self-help is no longer possible in this case. In severe cases of illness, the medication is administered as an infusion at the beginning. During the period of taking antibiotics, it is important to take the medication exactly as instructed by the doctor. One should pay attention to the signals of his body during this time, take care of himself and keep bed rest. After completing the course of antibiotics, it may be advisable to take medication to sanitize the intestines, as the intestinal flora may have been attacked by the therapy. To avoid re-infection, the source of the Legionella infection should be eliminated.
