More than 18,000 known people are hospitalized with Legionnaires' Disease each year and that number is likely low because the disease is not considered in the differential diagnosis or not reported to the state health departments.
Legionnaires' Disease is caused by a bacteria from the genus Legionella. There are more than 40 species, but the most common species causing 80-85% the diseases is L pneumophilia. The organism is found worldwide, but outbreaks of the disease seem to occur more frequently in the northeast part of the United States, England, Australia, and the Netherlands. This organism loves warm, damp environments and can survive for months in lakes and soil. Most outbreaks, however, have been reported through indoor water systems, pipes, spas, and air-conditioning systems. The temperature range at which the organism can actively grow ranges from 77 degrees F- 108 degrees F.
Transmission
The good news is that Legionnaire's Disease is not spread from person to person. The outbreaks that have been reported show that individuals have inhaled fine water droplets containing the bacteria which then invade the respiratory tract and begin to multiply.
Who is at Risk
As with most illnesses, not everyone becomes ill if exposed to a potential pathogenic organism. However, there are some individuals who are more vulnerable to becoming sick. Individuals who:
- are smokers
- have immunosuppressed disorders, such as HIV or cancer, or who are on medications that depress the immune system, such as Prednisone, or any chemotherapeutic agent.
- are alcoholics
- are male
- are middle aged or older
Signs and SymptomsThe incubation period between the time of exposure and onset of symptoms ranges from two to fourteen days. Symptoms include:
- shortness of breath
- chest pain
- mental status changes including confusion
- fever and chills, and
- cough.
Symptoms typically can last up to 8 weeks and can be fatal.
Making the Diagnosis
One can see that the diagnosis can be easily missed. Making the diagnosis takes an astute clinician who obtains a complete and thorough history in which all possible causitive agents are considered.
Special tests are needed to confirm the diagnosis in addition to a routine complete blood count with a differential, chest x-ray, and blood chemistries, including sedimentation rate, electrolytes, liver function tests and urinalysis. One test which can be ordered is a urine test specifically looking for the Legionella antigens. This is a rapid, inexpensive, and non-invasive test. The only drawback is that the test only detects L pneumonphiolia serogroup 1. Although this is the most common organism is most cases of Legionnaire's Disease, other testing may be required. Sputum cultures can be obtained but will require a special technique and results may take up to a week to confirm actual organisms. Blood cultures may also be taken and the organism isolated.
Treatment
Treatment for Legionnaire's Disease is usually with two potent classes of antibiotics, the macrolides (ie. azithromycin) and the quinolones ( ie.ciprofloxiacin). Luckily these medications are readily available, and are oral preparations. Individuals who are seriously ill will require hospitalization, IV therapy, and perhaps ventilatory support. The mortality rate ranges from 5%-40%, depending upon the underlying risk factors.
Though not a common disease, Legionnaire's Disease should be considered as a possibility if exposed to indoor water systems and plumbing.
Source
- Rhoads, J, and Mitchell, F.(January/February 2011). Legionnaires' Disease. The American Journal for Nurse Practitioners, 15, 1/2, 45-48.
Disclaimer: The information contained in this article is for educational purposes only and should not be used for diagnosis or to guide treatment without the opinion of a health professional. Any reader who is concerned about his or her health should contact a doctor for advice.
Rosemary King - Stay well; stay healthy; stay focused.
