Legionnaires' Disease

 Legionnaires' Disease

Overview

Legionnaires’ (LEE-juh-nares) disease is a type of pneumonia (lung infection) you get from breathing in Legionella bacteria. It can affect your lungs, brain and gut (gastrointestinal tract). Legionella also causes Pontiac fever, a less serious illness with flu-like symptoms. Legionnaires’ disease can be life-threatening.

You get Legionnaires’ disease when Legionella infects your lungs. Most people with Legionnaires’ disease who are hospitalized have fever and cough but may also have other pulmonary symptoms such as diarrhea and confusion.

Most people don’t get Legionnaires’ disease, even if they’ve been around Legionella bacteria. But some people are more likely to get sick with a Legionella infection than others. You have an increased risk of getting Legionnaires’ disease if you:

Are older than 50.

Smoke or used to smoke cigarettes.

Have a weakened immune system. Certain medical conditions (like HIV, diabetes, cancer and kidney or liver disease) and medications can compromise your immune system.

Have a long-term respiratory illness, such as chronic obstructive pulmonary disease (COPD) or emphysema.

Live in a long-term care facility.

Have stayed in a hospital recently.

Have had surgery requiring anesthesia recently.

Have received an organ transplant recently.

Symptoms

Legionnaires' disease usually develops two to 10 days after exposure to legionella bacteria. It frequently begins with the following signs and symptoms:

Headache

Muscle aches

Fever that may be 104 F (40 C) or higher

By the second or third day, you'll develop other signs and symptoms that can include:

Cough, which might bring up mucus and sometimes blood

Shortness of breath

Chest pain

Gastrointestinal symptoms, such as nausea, vomiting and diarrhea

Confusion or other mental changes

Although Legionnaires' disease primarily affects the lungs, it occasionally can cause infections in wounds and in other parts of the body, including the heart.

A mild form of Legionnaires' disease — known as Pontiac fever — can produce fever, chills, headache and muscle aches. Pontiac fever doesn't infect your lungs, and symptoms usually clear within two to five days.

Causes

The bacterium Legionella pneumophila is responsible for most cases of Legionnaires' disease. Outdoors, legionella bacteria survive in soil and water, but rarely cause infections. However, legionella bacteria can multiply in water systems made by humans, such as air conditioners.

Although it's possible to get Legionnaires' disease from home plumbing, most outbreaks have occurred in large buildings, perhaps because complex systems allow the bacteria to grow and spread more easily. Also, home and car air conditioning units don't use water for cooling.

How the infection spreads

Most people become infected when they inhale microscopic water droplets containing legionella bacteria. This might be from the spray from a shower, faucet or whirlpool, or water from the ventilation system in a large building. Outbreaks have been linked to:

Hot tubs and whirlpools

Cooling towers in air conditioning systems

Hot water tanks and heaters

Decorative fountains

Swimming pools

Birthing pools

Drinking water

Besides by breathing in water droplets, the infection can be transmitted in other ways, including:

Aspiration. This occurs when liquids accidentally enter your lungs, usually because you cough or choke while drinking. If you aspirate water containing legionella bacteria, you can develop Legionnaires' disease.

Soil. A few people have contracted Legionnaires' disease after working in a garden or using contaminated potting soil.

Risk factors

Not everyone exposed to legionella bacteria becomes sick. You're more likely to develop the infection if you:

Smoke. Smoking damages the lungs, making you more susceptible to all types of lung infections.

Have a weakened immune system. This can be a result of human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) or certain medications, especially corticosteroids and drugs taken to prevent organ rejection after a transplant.

Have a chronic lung disease or other serious condition. This includes emphysema, diabetes, kidney disease or cancer.

Are 50 years of age or older.

Legionnaires' disease can be a problem in hospitals and nursing homes, where germs can spread easily and people are vulnerable to infection.

Complications

Legionnaires' disease can lead to a number of life-threatening complications, including:

Respiratory failure. This occurs when the lungs can't provide the body with enough oxygen or can't remove enough carbon dioxide from the blood.

Septic shock. This occurs when a severe, sudden drop in blood pressure reduces blood flow to vital organs, especially to the kidneys and brain. The heart tries to compensate by increasing the volume of blood pumped, but the extra workload eventually weakens the heart and reduces blood flow even further.

Acute kidney failure. This is the sudden loss of your kidneys' ability to filter waste from your blood. When your kidneys fail, dangerous levels of fluid and waste accumulate in your body.

When not treated promptly, Legionnaires' disease can be fatal.

Diagnosis

Legionnaires' disease is similar to other types of pneumonia. To help identify the presence of legionella bacteria quickly, your doctor might use a test that checks your urine for legionella antigens — foreign substances that trigger an immune system response. Other tests might include:

Blood and urine tests

Chest X-ray, which doesn't confirm Legionnaires' disease but can show the extent of infection in your lungs

Tests on a sample of your sputum or lung tissue

Treatment

Legionnaires' disease is treated with antibiotics. The sooner therapy is started, the less likely the chance of developing serious complications. In many cases, treatment requires hospitalization. Pontiac fever goes away on its own without treatment and causes no lingering problems.

Type of Doctor Department :Infectious Disease Specialist