Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.
Age of Onset
Autosomal dominant ?A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease
Autosomal recessive ?Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype
X-linked dominant ?X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.
X-linked recessive ?Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder
Mitochondrial or multigenic ?Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.
Multigenic or multifactor ?Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.
Other Names (AKA)
Legionellosis; Legionnaires disease
Legionnaires’ disease is a severe type of pneumonia caused by the
Most people exposed to Legionella do not become sick with Legionnaires' disease. People who do become sick usually develop symptoms within 2 to 10 days after exposure, but it may take longer. The first symptoms may include headache, chills, muscle pains, and a fever that can be 104°F (40°C) or higher. Additional symptoms usually develop 1 to 2 days after the first symptoms and may include coughing, shortness of breath, chest pain, diarrhea, nausea and vomiting, and confusion. While Legionnaires’ disease mainly affects the lungs, it sometimes causes infections in other parts of the body, such as the heart or within body wounds.
A person can become infected from Legionella when they inhale mist or water droplets that contain the bacteria. Sources of exposure may include showers, faucets, whirlpools, grocery store misters, and water droplets passing through ventilation systems in large buildings (such as hotels, office buildings, and hospitals). People who are more susceptible to developing Legionnaires' disease after an exposure include adults over age 50, current or former smokers, and people who have a weakened
Legionnaires' disease may be suspected by symptoms. Pneumonia can be confirmed by a chest
Of note, Legionella can also cause a milder illness called Pontiac fever, which causes flu-like symptoms, but does not cause pneumonia. Pontiac fever typically goes away without specific treatment.
This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.
|Medical Terms||Other Names||
|80%-99% of people have these symptoms|
[ more ]
[ more ]
|30%-79% of people have these symptoms|
Abnormal heart rate
Heart rhythm disorders
Irregular heart beat
[ more ]
|5%-29% of people have these symptoms|
Pain in stomach
[ more ]
|Abnormal pleura morphology||0002103|
|Bone marrow hypocellularity||
Bone marrow failure
Bacterial infection of skin
[ more ]
[ more ]
Blood in urine
Coughing up blood
Low blood sodium levels
Low blood pressure
Yellowing of the skin
[ more ]
Swollen lymph nodes
Decreased blood lymphocyte number
Low lymphocyte number
[ more ]
Intermittent migraine headaches
[ more ]
Inflammation of heart muscle
|Nausea and vomiting||0002017|
Swelling or irritation of membrane around heart
High urine protein levels
Protein in urine
[ more ]
Recurrent sore throat
Disturbances of consciousness
[ more ]
Renal failure in adulthood
[ more ]
|Restrictive ventilatory defect||
Stiff lung or chest wall causing decreased lung volume
Infection in blood stream
Increased spleen size
Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.
- The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.
Conditions with similar signs and symptoms from Orphanet
The disease has no particular clinical features that clearly distinguish it from other types of pneumonia. Other bacterial (Streptococcus pneumonia, Staphylococcus aureus and Haemophilus influenza) or viral infections that cause pneumonia need to be ruled out.
Visit the Orphanet disease page for more information.
These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.
- You can obtain information on this topic from the Centers for Disease Control and Prevention (CDC). The CDC is recognized as the lead federal agency for developing and applying disease prevention and control, environmental health, and health promotion and education activities designed to improve the health of the people of the United States.
- The Mayo Clinic Web site provides further information on Legionnaires’ disease.
- MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
- The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.
- Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
- MeSH® (Medical Subject Headings) is a terminology tool used by the National Library of Medicine. Click on the link to view information on this topic.
- The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
- The Occupational Safety & Health Administration (OSHA) of the United States Department of Labor has a comprehensive online page on Legionnaires’ disease that covers topics such as general information, symptoms, incidence rates and risk factors, diagnosis, and treatment.
- Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine.
- Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
- PubMed is a searchable database of medical literature and lists journal articles that discuss Legionnaires’ disease. Click on the link to view a sample search on this topic.
- Legionnaires' disease. Mayo Clinic. January 11, 2018; https://www.mayoclinic.org/diseases-conditions/legionnaires-disease/symptoms-causes/syc-20351747.
- Cunha BA. Legionnaires Disease. Medscape Reference. June 9, 2017; https://emedicine.medscape.com/article/220163-overview.
- Legionella (Legionnaires’ disease and Pontiac Fever). Centers for Disease Control and Prevention (CDC). 2016; https://www.cdc.gov/legionella/index.html.
- Legionella (Legionnaires’ Disease and Pontiac Fever): Signs and Symptoms. Centers for Disease Control and Prevention (CDC). April 30, 2018; https://www.cdc.gov/legionella/about/signs-symptoms.html.
- Legionella (Legionnaires' Disease and Pontiac Fever): Causes, How it Spreads, and People at Increased Risk. Centers for Disease Control and Prevention (CDC). April 30, 2018; https://www.cdc.gov/legionella/about/causes-transmission.html.
- Legionnaires' Disease. MedlinePlus. March 25, 2016; https://medlineplus.gov/legionnairesdisease.html.
- Legionnaires’ Disease. National Organization for Rare Disorders (NORD). 2009; https://rarediseases.org/rare-diseases/legionnaires-disease/.
- Legionella (Legionnaires' Disease and Pontiac Fever): Diagnosis, Treatment, and Complications. Centers for Disease Control and Prevention (CDC). April 30, 2018; https://www.cdc.gov/legionella/about/diagnosis.html.