Legionnaires’ disease is a serious type of pneumonia caused by Legionella bacteria, and its symptoms can be quite varied but generally start with flu-like signs that worsen over several days. The illness usually begins within 2 to 10 days after exposure to the bacteria, although in rare cases symptoms can appear as late as 20 days afterward.
The most common symptoms include:
– **High fever**: Almost everyone with Legionnaires’ disease experiences a sudden and often very high fever, sometimes accompanied by chills.
– **Cough**: This can be a dry cough or one that produces sputum (mucus). About half of patients cough up sputum, and in some cases, the sputum may be bloody.
– **Shortness of breath**: Difficulty breathing or feeling breathless is common as the infection affects the lungs.
– **Muscle aches and pains**: Many people feel muscle soreness or aches throughout their body.
– **Headaches**: Persistent headaches often accompany the fever and muscle pain.
– **Fatigue and weakness**: A general feeling of tiredness and lack of energy is typical.
– **Gastrointestinal symptoms**: Up to half of those infected experience nausea, vomiting, diarrhea, or stomach pain. These symptoms can sometimes be severe and may precede the respiratory symptoms.
– **Neurological symptoms**: Confusion, disorientation, and impaired cognition can occur, especially in older adults or those with weakened immune systems.
– **Loss of appetite**: Many patients report not feeling hungry or having difficulty eating.
– **Chest pain**: Some people experience chest discomfort or pain, often worsened by coughing or deep breaths.
– **Excessive sweating**: Profuse sweating can accompany the fever and chills.
– **Relative bradycardia**: This is a less common symptom where the heart rate remains low or normal despite the presence of a high fever, which is unusual in most infections.
The symptoms can be severe and worsen over several days, often leading to pneumonia visible on chest X-rays, typically showing lung consolidation in the lower parts of the lungs. Because the symptoms overlap with other types of pneumonia and respiratory illnesses, Legionnaires’ disease can be difficult to diagnose based on symptoms alone.
People at higher risk of developing Legionnaires’ disease or experiencing more severe symptoms include those over 50 years old, smokers or former smokers, individuals with chronic lung diseases, and those with weakened immune systems.
In contrast, a related but milder illness called Pontiac fever, caused by the same bacteria, presents mainly with fever and muscle aches but without pneumonia and usually resolves within a few days without treatment.
Overall, the symptoms of Legionnaires’ disease reflect a serious lung infection combined with systemic effects that can involve the digestive system and the brain, making it a complex illness that requires medical attention.
