Diagnosing Legionella

Risk of infection is based on two key factors: the concentration of the Legionella and the resistance of the individual. Many sources claim that if you’re young and healthy that you can’t get the disease. There are no known numbers or comparison between immune system and the concentration of Legionella, making it impossible to know when you are completely safe or not. Generally people with weak immune systems such as organ transplant patients, cancer patients receiving chemotherapy, the elderly and smokers are more susceptibly to the disease.

Those who are sick or old have an increased risk of contracting Legionnaires’ disease and they have a higher risk of dying from the disease. Due to having a residency of people who have weakened immune systems, death rates in hospitals and nursing homes have a rate higher than most other types of buildings.

Legionnaires’ disease develops within 2 to 10 days after exposure to the bacteria. Symptoms may include loss of energy, headache, nausea, aching muscles, high fever (often exceeding 104°F) and chest pains. The disease eventually will cause death. Early diagnosis increases the chance of survival with the use of antibiotics. Without the timely diagnosis the lungs will become a breeding grounds for the bacteria causing your a fluid build-up in your lungs.

Testing

There are a quite a few tests that are done to check if a patient is thought to have Legionnaires’ disease. Usually the first involves a typical physical. A doctor will listen for lung sounds or what they call “crackles” in your chest. This is a sign of pneumonia. Other tests may include: arterial blood gas test, chest x-ray, white blood cell count test, a check of your erythrocyte sedimentation rate, liver function test, urine tests for the Legionella pnuemophila bacteria, sputum indirect fluorescent antibody test for Legionella bacteria and sputum culture for the Legionella bacteria.

Arterial Blood Gas Test

Blood is taken from the artery to determine the pH of the blood (which can reveal important clues about lung and kidney function and the body’s general metabolic state), the partial pressure of carbon dioxide, oxygen and bicarbonate level. Low oxygen levels will obviously show that there is a respiratory problem.

Chest X-ray

Looking for signs of fluid in the lungs.

White Blood Cell Count

An elevated number of white blood cells is called leukocytosis. This can result from bacterial infections, inflammation, leukemia, trauma, intense exercise, or stress. A decreased white blood cell count is called leukopenia. It can result from many different situations, such as chemotherapy, radiation therapy, or diseases of the immune system. Counts that continue to rise or fall to abnormal levels indicate that the condition is getting worse. Counts that return to normal indicate improvement.

Erythrocyte Sedimentation Rate

This test monitors cancerous and inflammatory diseases as well as autoimmune disorders.

Liver Function Test

Liver function tests help evaluate the overall health of your liver and can sometimes indicate other diseases.

Urine Test

This test detects the antigen to a species of bacteria called Legionella in urine.

Sputum Indirect Fluorescent Antibody Test

A test that looks for microorganisms in lung secretions.

Sputum Culture

This test is done to identify the type of bacteria that is causing the infection in the lungs.

Patient Treatment

Typically if there is any notice that a patient might have Legionnaires’ disease, treatment will occur before the actual tests have come back, to insure the safety of the patient in a timely manner. The treatment itself is pretty simple, several antibiotics are given as well as fluids and electrolytes to reduce the chance of dehydration. Oxygen is also given to help the weakened lungs to breathe.

Death rates from Legionnaires’ disease are highest with patients who are already in the hospital (up to 50%) due to their weakened immune system. The death rates in nursing homes are second highest due to the age factor. The elderly’s immune system is generally not strong enough to fight the disease without immediate help. Children and other younger, healthier people with strong immune systems can sometimes handle the bacteria on their own if the concentrations are low enough. However, since there is no way to tell at what concentration the bacteria is lethal, compared to a person’s immune system, the risk of not consulting a doctor can potentially be deadly. The best way is to ensure that your house or business building is designed to avoid the chance for Legionella bacteria to get to the point where it can be dangerous, since there is no way to completely avoid it.