Legionnaires’ Disease

A recent outbreak of Legionnaires’ disease has left 7 dead in Portugal. The World Health Organization (WHO) has declared the situation a major public health emergency and the Portuguese Health Ministry has reported 302 infected by the disease.

Given the fact that this disease tends to cluster in small outbreaks, I thought it would be a good idea if everyone learnt about the disease and how it spreads. Knowledge of the symptoms of the disease and knowing how to limit its spread can be very useful in such outbreaks.

Legionnaires’ disease is caused by a kind of bacteria of the same name. Ninety percent of the outbreaks are caused by a bacterium with the name Legionella pneumophila. The rod shaped little devil has a tiny whip like tail called flagellum. It loves to grow in moist conditions with lots of oxygen. This makes it very good at moving in stagnant warm water (like a hot tub, or an AC water condenser) and gravitating into a person’s lungs where it tends to set up an infection.

People who are most at risk from becoming gravely ill or even dying from a Legionnaires’ outbreak are:

• Individuals who are 50 years of age or older
• Smokers
• People with chronic lung disease
• Individuals with weakened immune systems

Outbreaks of Legionnaires’ disease are expected around situations where people share water that has been sitting, and its container has not been cleaned or sterilized properly.

In the US, sharing improperly cleaned hot tubs tend to be the cause of many an infection of the disease. In the ongoing outbreak in Portugal, the bacteria have been found in the refrigeration system of a fertilizer plant.

• The typical symptoms of the disease revolve around the respiratory system, a cough (either wet or dry) being the central symptom.
• As the immune system fights back, the patient will then notice chills and then a fever.
• As the immune system kicks into overdrive to combat the infection, other symptoms like nausea and vomiting can be seen.
• Of course, severe fatigue is understandable when your white blood cells are at war with tiny bacteria.

Chest x-rays of a patient suffering from the infection may show both lower lobes of the lungs getting whitened out. The definitive test is a sputum test or a urine test which detects the special proteins the immune system creates to combat the infection. This is called an antibody test and is very specific to Legionnaires’ disease and can be done on large numbers of people very quickly. It is useful in a situation like an outbreak.

Thankfully, the bacterium is still very sensitive to some of the higher antibiotics. Levofloxacin and Azithromycin are the two most commonly used antibiotics in the treatment of Legionnaires’ disease and so far they seem to work quite well. These are pretty commonly available medications in developed parts of the world.

More information about this disease can be found on the Centers for Disease Control (CDC) website.