News and Information on Infectious Disease
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Legionnaires’ disease is caused by a microbe called Legionella that can be found in warm, stagnant water and is known to grow in residential or commercial water systems, hot water tanks, hot tubs or other large water containment systems.

Legionnaires’ disease can be contracted at any time of year, but most infections occur in summer when air conditioning and whirlpool tubs are used most often.

If treated early, the damage to internal organs from Legionnaires’ disease can be significantly reduced or stopped altogether. By killing the bacteria, the patient can fully recover from all symptoms of the infection.

The Legionella bacteria has evolved quite well however, and essentially escapes eradication by killing the very defense mechanism our body uses to stop the disease.

What is Legionnaires’ disease?

Legionnaires’ disease is pneumonia that occurs as a result of infection from Legionella bacteria. Key symptoms consist of high temperature, chills, body aches, and dry scratchy throat with a cough. To be certain of a Legionnaires’ disease diagnosis, positive lab tests would need to show presence of the bacteria, antigens or antibodies created by the immune system. The people most at risk are the elderly, people with illnesses and those with deficient immune systems.

First diagnosed in 1976 when an outbreak of pneumonia among individuals at a convention in Pennsylvania were being reported. Investigation of the outbreaks soon uncovered that the unexplained pneumonia infections were associated with the bacteria. In the end, there were 86 confirmed cases with 18 of those resulting in death.

More recently, outbreaks have occurred on cruise ships where pools and spas may be poorly managed with improper chlorination and circulation of water.

What causes Legionnaires’ disease?

Legionnaires disease bacteriaWhen water becomes contaminated with the Legionella bacteria, aerosols may be inhaled exposing the body to Legionella. But, exposure to the bacteria does not always result in infection. Common ways to breathe in the contaminated water include poorly maintained industrial air conditioning systems, or other places where large volumes of standing water can become hot. The disease cannot be passed from person to person and cannot be contracted from automotive air conditioners. The bacteria is also present in soil and may be contracted by handling the soil or ingesting particles while stirring or sifting the soil contaminated with the Legionella bacteria.

Approximately 5% to 10% of Americans have been exposed to some extent, but most will never develop symptoms of an infection. Of all pneumonia cases for which the patient is hospitalized, only 2% to 15% are caused by the Legionella bacteria.

Who can get Legionnaires’ disease

Between 10,000 and 40,000 people in the U.S. contract Legionnaires’ disease every year. Those most likely to get the disease include people over 50 years of age, and with serious health problems. Some health issues that contribute to contracting the disease include diabetes, chronic lung disease, heart disease, kidney failure, or immune system deficiency. Cigarette smokers tend to have diminished immune system capacity, placing them at increased risk.

Those cases of infection in children normally involve newborns and those who had undergone a surgical procedure.

Fatality rates for healthy adults are generally around 5% and for those with existing illness and diminished immune systems the death rate increases to 25%.

When treated early, the body’s immune system can receive help to kill the bacteria and complete recovery is common.

What are symptoms of Legionnaires’ disease?

Initial symptoms will start to appear within 2 days to 10 days after exposure to the bacteria. If exposure leads to symptoms, they will include:

  • high temperature
  • chills and clammy skin
  • muscle and joint pain
  • headache
  • lethargy

The body’s defense mechanism is to attack the bacteria with cells designed to encase the bacteria and kill it. But, the bacteria have evolved to survive the attack and kill the body’s initial defense mechanism. At this point, the symptoms are somewhat more intense:

  • dry, hacking cough
  • difficulty breathing (1/2 of all cases)
  • extremely high temperature – as high as 104°
  • irregular heart rate

In many cases, the symptoms can be experienced in areas besides the lungs. About 50% of patients diagnosed with Legionnaires’ disease also report diarrhea and about 25% of those diagnosed have vomiting and nausea too.

Treatment of Legionnaires’ disease

Treatment of Legionnaires’ disease includes antibiotic therapy, with the leading choice being erythromycin oftentimes prescribed with another antibiotic called rifampin.

A treatment strategy must be immediately determined once diagnosis is confirmed.

Treating Legionnaires’ disease immediately with antibiotics will result in recovery after a couple of weeks from starting the treatment. Older people may take longer to recover, especially if their immune system is not functioning 100% or if they are suffering from another illness.

In no case should anyone self-diagnose. It is critical to properly identify the bacteria or the antibodies produced by the body to fight the bateria in order to have a positive diagnosis. See your doctor.

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