What is Legionnaires Disease?
In 1976, a pneumonia outbreak occurred during a convention held by the American Legion in Philadelphia. After investigations, it was found that a bacterial species named Legionella pneumophila was responsible for the outbreak, thus leading to the term Legionnaires disease. It was established that the bacteria had spread through aerosols from the water in the convention’s air conditioning system.
People affected by this bacteria developed different levels of illness, ranging from flu-like symptoms to severe organ failure, and tragically, some died. Legionnaires disease is a unique type of pneumonia that often shows different clinical symptoms compared to other bacterial pneumonia. Those infected might experience predominantly fever, cough, shortness of breath, headache, and fatigue.
After exposure to contaminated water, it can take between 2 to 10 days for Legionella pneumophila symptoms to appear. On X-rays, lungs infected with this bacteria sometimes look patchy, fluffy, and concentrated within certain areas, although these observations can vary. Other symptoms like thick mucus or coughed-up material, intense chest pain, and fluid build-up around the lungs may be less common with this infection compared to other types of bacterial pneumonia. However, additional symptoms like diarrhea and confusion can raise suspicion for Legionnaires disease.
Lab test findings such as low sodium levels in the blood, signs of kidney injury, and increased levels of certain proteins or enzymes can indicate an infection. Therefore, diagnosing Legionnaires disease involves considering these symptoms, lab tests, and X-ray results. Treatment typically involves antibiotics effective against bacteria that live inside cells, such as fluoroquinolones, macrolides, or tetracyclines.
Legionnaires disease is a significant public health issue as it can lead to outbreaks, can be fatal if left untreated, and its diagnosis and control can be challenging. Current research is trying to understand more about how Legionella pneumophila spreads and causes disease in humans, to develop more effective prevention methods and treatments. Preventing the disease largely involves maintaining and disinfecting water systems properly to reduce the risk of bacterial growth and people’s exposure to it.
What Causes Legionnaires Disease?
Legionella bacteria are a varied group of germs that thrive in water. These bacteria can cause illnesses in humans, with Legionella pneumophila, particularly group 1 variety, being the most common cause. It’s estimated that this specific variant is responsible for around 80% of all pneumonia cases caused by this bacterium. There are more than 15 types of Legionella bacteria, but only type 1, 4 and 6 usually cause illnesses in humans.
Legionella bacteria are naturally found in bodies of fresh water like lakes and streams. However, they can survive in different conditions and inside different organisms, like tiny water-dwelling creatures known as protozoa and amoebae. Humans usually get Legionella infections by inhaling tiny water droplets from infected sources in the environment like soil or water.
These bacteria prefer warm water, between 68°F and 107.6°F, as it helps them grow and spread. They can adapt well to human-made water systems in buildings, like those in healthcare facilities, by creating a slimy layer called biofilms and by resisting cleaning agents. They can live inside other organisms like protozoa, which also helps them survive. These biofilms and the relationship with these tiny creatures create a sort of storage hub, that can contaminate water supplies. This contaminated water can infect people when they breathe in tiny droplets of the water.
Risk Factors and Frequency for Legionnaires Disease
Legionellae are bacteria that are found everywhere and can infect humans through aerosolized water from the environment or water systems in buildings. The actual number of people who get Legionnaires disease, the illness caused by these bacteria, is not clearly known as many countries don’t have proper methods for diagnosis, surveillance, or reporting.
In the United States, 60% to 65% of cases are due to contaminated water, making it the leading cause of waterborne infections. These infections can occur randomly or as outbreaks from contaminated water sources in large buildings and facilities like hotels, hospitals, and long-term care homes. Legionnaires disease is often associated with travel, usually linked to hotels with contaminated water systems or hot tubs. In the U.S., about 20% of cases are related to travel or healthcare facilities.
- Legionellae are bacteria that are found everywhere and infect humans through aerosols of contaminated water.
- In the U.S., these bacteria are the leading cause of waterborne infections.
- About 60% to 65% of cases are due to contaminated water.
- The disease can occur randomly or can outbreak from contaminated water sources in large facilities like hotels and hospitals.
- Legionnaires disease is often linked to travel, especially hotels with contaminated water systems or hot tubs.
- Approximately 20% of the cases in the U.S. are tied to travel or healthcare facilities.
According to the Centers for Disease Control and Prevention (CDC), the reported cases of Legionnaires disease in the U.S. have risen quickly since 2000. In 2018, 9,933 cases were reported to the CDC, with a death rate of 10%. Nevertheless, many infections are undiagnosed, and many cases are not reported.
Approximately 10% of Legionnaires cases worldwide are diagnosed in the U.S., resulting in 8,000 to 18,000 hospitalizations every year. The disease is more common in Ohio, Pennsylvania, New York, and Illinois. Yet, it’s important to keep in mind that the disease has been reported worldwide, including in Europe, Asia, Africa, and Latin America.
- Reported cases of Legionnaires disease in the U.S. have risen rapidly since 2000 according to CDC.
- In 2018, there were 9,933 cases, with a death rate of 10%.
- Many infections are undiagnosed, and many cases are not reported.
- About 10% of cases worldwide are diagnosed in the U.S., causing 8,000 to 18,000 hospitalizations each year.
- The disease is more common in Ohio, Pennsylvania, New York, and Illinois.
- The disease is a global problem, with cases reported in Europe, Asia, Africa, and Latin America.
Legionnaires disease is more common during the summer and early fall when water temperatures are warmer. Anyone can get the disease, but it’s more dangerous for senior citizens, people with chronic lung conditions, those with weak immune systems, and individuals who use tobacco.
- Legionnaires disease is more common during the summer and early fall when water temperatures are warmer.
- The disease is riskier for older adults, people with chronic lung conditions, those with weak immune systems, and individuals who use tobacco.
Signs and Symptoms of Legionnaires Disease
When seeing a patient with a respiratory complaint, it’s very important to get a full medical history and details about potential exposure to harmful bacteria. Specifically, patients should be asked about situations that could increase exposure to a type of bacteria called Legionella pneumophila. This might include information about any recent international or domestic travel, hobbies, or contact with water systems that could be contaminated. Water systems can include things like air conditioners, industrial cooling towers, hot tubs, or decorative fountains. Certain jobs, like construction or healthcare, or working in buildings with complex plumbing systems might also put a person at a higher risk. Other relevant information in the medical history could be if the patient is a smoker, has a chronic lung disease, has a weakened immune system, has been near sick people, or knows they’ve been exposed during an outbreak.
The time between exposure to Legionella pneumophila and the appearance of symptoms (incubation period) is typically 2 to 10 days. Symptoms of the infection, called legionellosis, include tiredness, a fever, cough, muscle aches, a headache, chest pain, and shortness of breath. Tiredness and a fever usually show up before the cough. Although most symptoms resemble those of other types of pneumonia, certain symptoms, like nausea, vomiting, and confusion, can raise suspicions of legionellosis.
A thorough physical examination is needed to identify the signs of pneumonia, which can include symptoms like fever, rapid breathing, a dry or productive cough, shortness of breath, and crackling sounds in the lungs. In more severe respiratory cases or infections outside the lungs, additional indicators could be low blood pressure, rapid heart rate, blue-tinted skin or lips (cyanosis), altered mental status, symptoms similar to meningitis (meningismus), and signs of heart infection (endocarditis).
Testing for Legionnaires Disease
Legionnaires disease, a type of lung infection, can often be hard to distinguish from other causes of pneumonia. However, specific symptoms and lab test results can help in diagnosing the illness. These symptoms include, but aren’t limited to, nausea, diarrhea, low sodium levels (hyponatremia), presence of blood in urine not visible to the naked eye (microscopic hematuria), and high erythrocyte sedimentation rate or C-reactive protein levels. These are inflammation markers in the blood and can be checked via blood tests. Early diagnosis and prompt treatment with antibiotics can improve chances of recovery and reduce the risk of death.
Different tests can be used for diagnosing Legionnaires disease:
1. The first one is called a urine antigen test. This test involves checking your urine for substances called antigens that are produced by the Legionella pneumophila bacteria. This test is quick, widely available and has a high accuracy rate.
2. Another option is a sputum culture test. This involves testing the mucus that you cough up from your lungs. This test can identify the specific type of bacteria causing the disease and determine which antibiotics will be most effective. However, results from this test can take a few days and its accuracy decreases if you are already on antibiotics.
3. Polymerase chain reaction (PCR) test is also an option. It checks for the DNA of the Legionella bacteria in various bodily fluids or tissues. It is a very sensitive and specific test that can provide findings within a few hours. However, it may not be widely available, requires specialised equipment and cannot predict antibiotic response.
4. In addition to these, antibody detection tests on blood samples can be used. These tests detect antibodies that your immune system develops in response to the Legionella bacteria. They are usually used to confirm a diagnosis after you have recovered.
The process of diagnosing Legionnaires’ disease can be complex and clinical criteria has been developed to support the diagnostic process. Accurate diagnosis can often involve taking into account laboratory results, symptoms such as fever and cough, and the presence or absence of specific factors in the bloodwork, such as sodium levels and C-reactive protein levels.
Patients with severe Legionnaires disease typically show bilateral lung infiltration, meaning both lungs are affected. They also show at least two of the following: rapid breathing (more than 30 breaths per minute), a low diastolic blood pressure (less than 60 mm Hg), and a high blood urea nitrogen level (at least 30 mg/dL).
In terms of imaging, chest X-ray is the most common procedure used to visualize lung disease in patients with Legionnaires. It usually shows patchy or diffuse infiltration in the lungs. If more detailed images are required, a computed tomography (CT) scan of the chest can be done to get a clearer view of the lung tissue.
Treatment Options for Legionnaires Disease
Legionnaires disease is often a severe illness that can lead to serious complications and even death. It usually requires patients to be admitted to the hospital for treatment. The goal of treatment is to target bacteria inside the body cells, and the preferred medicines used belong to the classes of drugs called macrolides and fluoroquinolones.
The choice of medication to treat Legionnaires disease varies and can depend on several factors such as the severity of the infection, any other health conditions the patient might have, any known allergies, antibiotic resistance, and the availability of medication. Some research and guidelines suggest that macrolides may be a more effective choice over fluoroquinolones.
Treatments usually start with drugs administered directly into the vein, and then, when the patient’s condition improves, transition to oral medications. Always refer to the most recent treatment guidelines for the best practices.
Supportive care for a patient with Legionnaires disease is crucial to aid in their recovery. This includes providing extra oxygen for patients who are struggling to breathe or have low oxygen levels, as well as giving additional fluids to those with serious illness, low sodium levels in their blood, or kidney issues. Patients who are seriously ill might also receive corticosteroid therapy. Corticosteroids are a type of medication used to reduce inflammation in the lungs and improve how the lungs are working.
What else can Legionnaires Disease be?
When a person gets pneumonia outside of a hospital or healthcare setting (known as community-acquired pneumonia), it’s often due to bacteria or viruses. The common culprits include bacteria such as Streptococcus pneumoniae or Staphylococcus aureus. There’s also a form of pneumonia caused by “atypical” bacteria including Chlamydophila pneumoniae, Chlamydia psittaci, or Mycoplasma pneumoniae, among others.
For patients who are very ill or critically ill, it’s important to consider other bacterial and viral diseases that can also cause septic shock and multiple organ failure. These are severe conditions where the body’s response to infection injures its own tissues and organs.
What to expect with Legionnaires Disease
The recovery outcomes for people diagnosed with Legionnaire’s disease can vary a lot. Severe infections, particularly in older people, individuals with weakened immune systems, and cases where the disease is diagnosed or treated late can lead to various health complications. Nearly everyone diagnosed with L pneumophila pneumonia, a particular type of Legionnaires disease, ends up in a hospital, with half of these cases needing intensive care.
The fatality rate for this disease in the United States is around 10%. However, this can differ depending on how and where the infection was acquired. The fatality rate of Legionnaires disease caught in a healthcare facility can be as high as 46%, while rates associated with infections acquired during travel or outbreaks range from 5% to 15%. In older patients, the mortality rate can be anywhere between 10% and 50%.
The stage and severity of the infection when treatment begins can greatly affect recovery outcomes. Patients with mild or moderate symptoms who get diagnosed and start treatment before the pneumonia becomes severe or results in systemic complications usually have better outcomes.
The disease is riskier for men, individuals aged 50 years or older, people with underlying cancers or weakened immune systems, as well as those with type 2 diabetes or chronic kidney disease. The situation can become worse if patients develop further health complications like respiratory failure, septic shock (an extreme infection that leads to low blood pressure), acute kidney injury, or failure of multiple organs. Delays in diagnosis or treatment also lead to worse outcomes.
Possible Complications When Diagnosed with Legionnaires Disease
Legionnaires disease can lead to a range of complications, which, if not identified and managed quickly, can worsen the patient’s health considerably. Some of the problems caused by this disease include severe breathing difficulties often needing artificial ventilation and special care, a life-threatening state caused by infection, failure of many organs at the same time, sudden kidney damage, issues in the nervous system, heart infection, and even death.
Common Complications:
- Severe breathing difficulties
- Life-threatening state due to infection (septic shock)
- Failure of multiple organs
- Sudden kidney damage
- Neurological issues
- Heart infection (endocarditis)
- Potential death
Recovery from Legionnaires Disease
People with Legionnaires disease often need to be admitted to the hospital. They may need support with a machine to help them breathe (mechanical ventilation), and they could require a special method of feeding that bypasses the usual process of eating and digestion (parenteral nutrition). These patients might also need rehabilitation both during their hospital stay and after they go home.
Preventing Legionnaires Disease
Teaching people about the risks for Legionella pneumophila pneumonia, a type of lung infection, can help raise awareness of who is more likely to get Legionnaires disease. This includes older people, those with weakened immune systems, and people with lung problems. It’s also important to teach both the public and healthcare teams about the common signs of Legionnaires disease, which include fever, cough, and breathing difficulties.
This education helps people to recognize the disease early and get medical help in time. It’s particularly important for people showing signs of pneumonia to see a doctor quickly. Getting diagnosed and starting treatment promptly can improve recovery significantly.
Guidance on how to stay safe in places like hotels or public places with water systems is especially important for people at higher risk. This is because these types of environments can sometimes harbor the bacteria that cause Legionnaires disease.