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What Is Legionella Urinary Antigen?

Legionella urinary antigen is a substance in the urine of a patient who is infected with legionella bacteria. Doctors use a urine test to identify this antigen when they diagnose Legionnaires' disease. People with this disease develop severe pneumonia and other serious symptoms. A mild form of the disease is called Pontiac fever.

  1. Legionella Urinary Antigen

    • Physicians prescribe a urine antigen test because the presence of legionella antigens in urine is a reliable indicator that a patient has Legionnaires' disease. Legionella urinary antigens may remain in a patient’s urine for several months after a patient has been successfully treated for Legionnaires' disease. The legionella antigen urine test identifies the antigen that is associated with one form of legionella bacteria that causes more than 80 percent of the diagnosed cases of Legionnaires' disease, according to OSHA.

    Diagnosis and Treatment

    • Doctors may have patients take other medical tests in addition to a urinary antigen test to help them diagnose Legionnaires' disease. Patients may have a chest X-ray taken to detail the spread of a legionella pneumonia infection in the lungs. A spinal tap or computerized tomography scan of the brain may be used to find the source of neurological symptoms of Legionnaires' disease. Doctors treat Legionnaires' disease with antibiotics, but milder Pontiac fever usually goes away on its own without medication.

    Legionnaires' Symptoms

    • Individuals with Legionnaires' disease may develop severe pneumonia and a fever of 104 degrees F or higher. Patients may experience muscle pains, chills and headaches. Shortness of breath and chest pain may develop as the infection worsens. Patients may have a serious cough and may cough up blood or mucus. Vomiting, diarrhea and a loss of appetite have been reported with this disease. People with Legionnaires' disease may experience confusion and changes in mental functioning.

    Pontiac Fever

    • Pontiac fever is a milder form of Legionnaires' disease and is also caused by legionella bacteria. This condition usually clears up after two to five days of symptoms and it does not affect a patient’s lungs. Sufferers of Pontiac fever may notice headaches and muscle aches. This condition may cause a fever and chills. Individuals with Pontiac fever may have a hypersensitive reaction to legionella bacteria that does not result in a complete Legionnaires' infection.

    Causes and Risks

    • Legionnaires' disease is spread by inhalation of legionella bacteria in warm and damp environments where the bacteria thrive. Whirlpool spas, air conditioning systems and water systems can provide ideal environments for these bacteria to grow. These bacteria may travel up to four miles in airborne water droplets and still cause an infection when the droplets are inhaled. People who smoke, have a lung disease or have a weakened immune system have a greater risk of developing Legionnaires' disease.

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