All of the following are seen in legionnaire’s disease except: September 2009
**Legionnaire's Disease**
### Core Concept
Legionnaire's disease is a type of pneumonia caused by the bacterium *Legionella pneumophila*. It is a zoonotic infection, meaning it can be transmitted from animals to humans, and typically occurs through inhalation of aerosolized water droplets contaminated with the bacteria.
### Why the Correct Answer is Right
The correct answer is one of the options listed below. We will identify it after explaining why each option is incorrect. Legionnaire's disease is characterized by fever, headache, and a severe type of pneumonia. The bacteria can cause a systemic inflammatory response syndrome (SIRS) and multi-organ dysfunction, particularly affecting the lungs, kidneys, and central nervous system. The pathogenesis of Legionnaire's disease involves the bacteria's ability to evade the host's immune system and replicate within macrophages and other cells.
### Why Each Wrong Option is Incorrect
**Option A:** Hyponatremia
* This is incorrect because Legionnaire's disease is typically associated with a mild to moderate elevation in sodium levels, not hyponatremia.
**Option B:** Hemoptysis
* This is incorrect because hemoptysis (coughing up blood) is more commonly associated with other types of pneumonia, such as pneumococcal pneumonia or tuberculosis.
**Option C:** Gastrointestinal symptoms
* This is incorrect because Legionnaire's disease is primarily a respiratory infection, and while some patients may experience mild gastrointestinal symptoms, they are not a prominent feature of the disease.
**Option D:** Elevated liver enzymes
* This is incorrect because Legionnaire's disease is not typically associated with elevated liver enzymes.
### Clinical Pearl / High-Yield Fact
Legionnaire's disease should be considered in the differential diagnosis of pneumonia, especially in patients with a history of exposure to contaminated water sources, such as hot tubs or air conditioning units.
### Correct Answer: C. Gastrointestinal symptoms.