11 March 2019 The disease develops in two to 10 days (normally five to six) after breathing warm, humid air contaminated with the bacteria. The name of the disease and bacterium comes from its original discovery at a convention of the American Legion (a US war veteran association) in Philadelphia in 1976. More than 200 delegates developed severe pneumonia and 31 of them died. When the bacterium was identified in 1977, it was named Legionella , and the infection became known as legionnaires' disease. How can you catch legionnaires' disease? A person can be infected by breathing in Legionella in the air, in the form of very small microscopic water droplets (aerosols) containing the bacteria. Legionella lives in warm water (25ºC-42ºC) and in nature (ponds, rivers, soil) and man-made systems (plumbing, taps, showers, toilet flushes, swimming pools, jacuzzis, spas, industrial cooling systems and air conditioning). You cannot get the disease by drinking water with Legionella . Legionella is not transmitted person to person. What are the main symptoms of legionnaires' disease? Legionella essentially causes lung disease. Its symptoms are non-specific and common to flu and colds: Dry cough; Fever; Chills; Headache; Muscle pain; Breathing difficulty; Abdominal pain; Diarrhoea. Over time, there are warning signs that some patients start to experience, indicating the disease may be developing into a more serious condition: Shortness of breath; Tiring easily; Difficulty in completing sentences; Feeling sleepy and listless. Who is at risk of legionnaires' disease? Some people are at risk of becoming seriously ill and need to be admitted to hospital, possibly in an intensive care unit. The main risk groups are: People over the age of 50; Smokers; People with chronic lung disease (bronchitis, emphysema, etc); People with a weakened immune system due to disease or treatments (chemotherapy, among others). How is legionnaires' disease diagnosed? From the combination of symptoms described by patients and their history of exposure to aerosols. This exposure can be confirmed with simple lab tests (in most cases a simple urine test can detect the bacteria). How is legionnaires' disease treated? Legionella infection can be treated with appropriate antibiotics . Success of the treatment depends on timely administration of an antibiotic. Patients must clearly explain their symptoms and history of probable inhalation of aerosols. Physicians also have to be very careful to obtain this information so that they can order the right tests. The disease’s severity also depends on the amount of Legionella inhaled and the person belonging to at least one of the risk groups. What can I do to reduce the risk of infection? There are some measures that can help you prevent the disease: Avoid breathing water vapour in showers, swimming pools, jacuzzis and places where hygiene seems doubtful or unknown, especially if you belong to a risk group for serious disease; Clean tap filters and dip shower heads in bleach and wipe them carefully afterwards; Avoid breathing in the first vapours from still water (e.g. in water heaters and geysers that have not been used for some time). When should I consider that I have legionnaires' disease and what should I do? If you have the described symptoms and have been exposed to suspect aerosols, especially if there are other known cases in the same area, contact the 24/7 Health Line (808 24 24 24) before going to your doctor or a hospital emergency unit. Explain your symptoms clearly in the hospital emergency department and tell them that you have inhaled aerosols. Remember in most cases the symptoms you have are not caused by Legionella ! This article was written with the support of physicians and other clinical professionals from the Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
