Legionnaires’ disease is a severe, often lethal, form of pneumonia. It’s caused by the bacterium Legionella pneumophila found in both potable and nonpotable water systems.
Legionnaires’ disease, or Legionellosis, is a severe infection caused by Legionella species, primarily L. pneumophila. In fact, L. pneumophila is responsible for 90% of infections. The disease typically presents as pneumonia and symptoms may include a high fever, chills, cough, muscle aches, headaches, and diarrhea.
How do people contract Legionella?
The most popular theory is that the organism is aerosolized in water and people inhale the droplets containing Legionella. However, new evidence suggests that another way of contracting Legionella is more common. “Aspiration” is the most common way that bacteria enter into the lungs to cause pneumonia. Aspiration means choking such that secretions in the mouth get past the choking reflexes and instead of going into the esophagus and stomach, mistakenly, enter the lung. The protective mechanisms to prevent aspiration is defective in patients who smoke or have lung disease. Aspiration now appears to be the most common mode of transmission.
What are the symptoms of Legionnaires’ disease?
The incubation period of Legionnaires’ disease is from two to ten days; this is the time it takes before symptoms of the illness appear after being exposed to the bacteria. For several days, the patient may feel tired and weak. Most patients who are admitted to the hospital develop a high fever, often greater than 39.5°C (103°F). A cough can be the first sign of a lung infection. The cough may be sufficiently severe to cause sputum production (coughed up mucous). Gastrointestinal stomach symptoms are common with diarrhea being the most distinctive symptom. Many patients have nausea, vomiting, and stomach discomfort. Other common symptoms include headaches, muscle aches, chest pain, and shortness of breath.
The symptoms of Legionnaires’ disease are similar to the symptoms of the flu:
- high temperature, feverishness and chills;
- muscle pains;
- headache; and leading on to
- pneumonia, very occasionally
- diarrhoea and signs of mental confusion
Legionnaires’ disease is not known to spread from person to person.
How is Legionnaires’ disease treated?
Many antibiotics are highly effective against Legionella bacteria. The two most potent classes of antibiotic are the macrolides (azithromycin), and the quinolones (ciprofloxacin, levofloxacin, moxifloxacin, gemifloxacin, trovofloxacin). Other agents that have been shown to be effective include tetracycline, doxycycline, minocycline, and trimethoprim/sulfamethoxazole.
Erythromycin, the former antibiotic of choice, has been replaced by more potent and less toxic antibiotics.
What to do
- If you develop the above symptoms and you are worried that it might be Legionnaires’ disease, see your general practitioner.
- It is not always easy to diagnose because it is similar to the flu. A urine or blood test will be helpful in deciding whether an illness is Legionnaires’ disease or not. When doctors are aware that the illness is present in the local community, they have a much better chance of diagnosing it earlier.
- If you suspect that your illness is as a consequence of your work then you should report this to your manager, as well as your health and safety representative and occupational health department, if you have one. There is a legal requirement for employers to report cases of Legionnaires’ disease that may be acquired at their premises to the Health and Safety Executive.