Legionnaires’ Disease – Causes and Prevention

Legionnaires’ disease can be serious, but most of us are not at risk.

I've been hearing about Legionnaires’ disease lately and it has caused me to look more closely at it. What is Legionnaires’ disease, how is it transmitted and who is at risk of contracting it?

Legionnaires’ disease is a type of pneumonia that affects the lungs. It is a very serious infection that is caused by a bacteria called legionella. According to the Centers for Disease Control and Prevention (CDC), the symptoms may include cough, shortness of breath, muscle aches, headache and/or high fever. A physical exam from your doctor and/or a chest x-ray will determine if you have pneumonia. If so, tests of urine and phlegm will tell if legionella is the cause of the lung infection.

Legionella bacteria thrive in water. The bacteria can grow in building water systems that are not properly maintained. The types of systems include air conditioning systems with cooling towers, water heaters, hot tubs, spas and warm, stagnant water. Legionella bacteria don’t tend to spread between people. Legionnaires’ disease is not spread through drinking water, but may be contracted through aspiration. Aspiration can happen if a liquid accidentally enters your lungs when you cough or choke while drinking. If the liquid you aspirate is water that contains legionella bacteria, then you might develop Legionnaires' disease.

Most people who are exposed to legionella bacteria won’t get sick because they have resistance to the disease. Legionnaires’ disease is also not common in children. According to the CDC, there are some factors that may increase the risk of a person getting sick, including:

  • Being a smoker, or a former smoker
  • Being 50 years or older
  • Having a chronic lung or respiratory condition, like emphysema or chronic obstructive pulmonary disease (COPD)
  • Having other medical conditions such as cancer, diabetes or HIV/AIDS
  • Taking drugs that reduce the ability to fight infections, such as steroids

The chances of legionella developing in home water systems are much smaller than in large public buildings systems. Complex systems in large public building allow the bacteria to grow and spread more easily. There are steps you can take to prevent Legionnaires’ disease in your home, though. If you have a hot tub or a warm pool, make sure your chlorine (or other disinfectant) levels are correct so that legionella bacteria are killed. These disinfectant levels can be difficult to regulate in warm or hot water. Maintain domestic water heaters at 140 degrees Fahrenheit (60 degrees Celcius). The temperature of the water should be 122°F (50°C) or higher at the faucet. This could cause scalding for small children or infirm elderly persons, so if you have people living with you who are at high risk of contracting the disease, then you should operate the water heater at a minimum temperature of 140°F (60°C) and consider installing a scald-prevention device.

Avoiding smoking is the single most important thing that you can do to lower your risk of contracting Legionnaires’ disease. Smoking increases the chances of developing the disease if you’re exposed to legionella bacteria.

There are no vaccines that can help protect you from Legionnaires’ disease. There are vaccines, though, that can prevent other types of pneumonia. They are the pneumococcal and flu vaccines. The CDC recommends that children younger than five years, all adults age 65 and older and people six years or older with certain risk factors should get the pneumococcal conjugate vaccine (PCV13). All adults age 65 or older should also get the pneumococcal polysaccharide vaccine (PPSV23). This vaccine is also recommended for people aged two through 64 years who are at high risk of pneumococcal disease. Everyone six-months-old or older should get an annual flu vaccine.

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