Related articles: Legionellosis
Definition
Legionellosis is an infectious disease caused by the bacterium Legionella pneumophila . This micro-organism reproduces quickly in hot-humid environments, especially in water pipes and air conditioners.
Infection is usually acquired by inhaling droplets of water heavily contaminated by the bacterium (aerosol), generated, for example, by showers, nebulizers to irrigate gardens or air conditioning systems in large buildings, such as hotels, barracks or hospitals.
The lungs are the site most affected by the infection which, in most cases, determines a form of pneumonia.
Legionellosis affects mainly the elderly, smokers and immuno-compromised patients or those with previous lung diseases.
Most common symptoms and signs *
- Anorexia
- Asthenia
- Chills
- Diarrhea
- Difficulty concentrating
- Dyspnoea
- Abdominal pain
- Chest pain
- Articolar pains
- Muscle pains
- hemoptysis
- Hemoptysis
- Temperature
- Lethargy
- Headache
- Nausea
- Drowsiness
- Confusional state
- Cough
Further indications
After a week of infection, legionellosis causes atypical pneumonia with high fever, chills, headache, myalgia, lethargy, confusion and malaise. Frequently, lack of appetite, nausea, watery diarrhea, abdominal pain, dry cough and arthralgia also occur. Pulmonary manifestations may include dyspnea, pleural pain and hemoptysis.
In some cases, an extrapulmonary infection develops with spontaneous and less severe resolution, called Pontiac fever, without pneumopathy, but with a flu-like syndrome characterized by asthenia, fever, headache, myalgia and general malaise. Legionellosis, however, can also be located in other body areas; Possible outbreaks of extrapulmonary infection are the heart, the CNS, the liver and the intestine. In immunosuppressed patients, it is possible that the disease gives rise to sinusitis, peritonitis, pyelonephritis, cellulitis, pancreatitis, cardiac or respiratory failure.
Diagnosis requires culture of the sputum or bronchoalveolar lavage fluid, necessary for identification of the responsible microorganisms, direct immunofluorescence tests, serological tests and PCR analysis. Furthermore, a chest X-ray must be performed, which in case of positivity shows pulmonary infiltrates with or without small pleural effusions, a non-specific sign of pneumonia.
The therapy requires the administration of specific antibiotics for 2-3 weeks (doxycycline, macrolides or fluoroquinolones). In the absence of adequate treatment, legionellosis evolves towards a gradual deterioration. Mortality is low in healthy patients, but can reach 50% in epidemics of nosocomial pneumonia.
