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About 8 percent of all pneumonias and 4 percent of fatal pneumonia is caused by legionnaires disease. Legionnaires disease is caused by a bacerium known as legionella pneumophila, as well as, other species of legionella. It strikes its victims in early fall or late summer. The legionella bacteria can live in water and has thus been spread through air conditioning systems in hotels and hospitals. This disease was found and given its name when there was an outbreak of respiratory illness that caused twenty nine deaths among American Legion members who were attending a convention in a Philadelphia hotel in 1976. When test were run the causative organism proved to be a common contaminant of water systems that was responsible for earlier epidemics of pneumonia that had not been understood in previous cases. To date there have been no cases of this disease where one person has been directly infected by another person.
In most cases the first symptoms will develop within a week of infection. These symptoms may include muscular and abdominal pain, fatigue, headaches, a dry cough and diarrhea. After a few days pneumonia will develop creating additional symptoms such as a high fever, shortness of breath, chills that cause the patient to shake, drowsiness, occasional delirium and the coughing up of a thick phlegm. Unless treated immediately the disease will become even more severe creating progressively worse breathing problems. In all cases the person must be admitted to a hospital. There a sample of the spatum will be taken for analysis or a lung biopsy will be done to reveal the micro organism that is responsible for the illness. Blood test and urine test will be done to confirm the diagnosis. In most cases people that are infected with legionella pneumophila will produce antibodies to fight the disease, these are shown in increasing concentration in the blood test. Even so, the results of these test are usually not available until the pneumonia has run its course. Thus, they will be given the antibiotic erythromycin, usually intravenously, which will relieve the symptoms quickly. In some cases the antibiotic rifampin may be required as well. In most cases a patient who is treated with erythromycin will show signs of getting better but a full recovery can still take a long time.
The bacterium that causes Legionnaires disease easily breeds in warm, moist conditions. The source of most outbreaks have come from water or air conditioning systems in large public buildings. Once the droplets of heavily contaminated water from the air conditioning or showers have been inhaled the infection will follow. This is known to happen both in localized outbreaks and as isolated cases. People who are elderly, heavy smokers, take corticosteriods and heavy drinkers are at a higher risk with this disease. The symptoms can be relatively minor or life threatening once the infection starts. Although younger people tend to recover fully from legionnaires disease, a substantial amount of elderly or previously ill people tend to die from the irreversible lung damage done by this disease. In the United States alone, over 700 cases of legionnaires disease are reported each year but it is believed that the true number of incidents is higher. It is also believed that around two percent of hospital cases of pneumonia may be caused by this disease.
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