# Does Legionnaires' disease spread from person to person? Canonical page: https://clinicsjo.com/en/faq/does-legionnaires-disease-spread-person-to-person Language: en Category: infectious Publisher: ClinicsJo Published: 2026-09-13T08:09:52.281Z Content updated: 2026-09-13T08:09:52.281Z Translation (ar): https://clinicsjo.com/ar/faq/does-legionnaires-disease-spread-person-to-person No, Legionnaires' disease is not contagious and does not spread directly from one person to another. This bacterial infection, caused by *Legionella* bacteria, spreads primarily when people inhale tiny water droplets or mist containing the bacteria. These bacteria typically grow and spread in industrial water systems, rather than within the human body in a way that allows for direct transmission to others. Outbreaks can occur when many people are exposed to the same water source contaminated with the bacteria. Although the disease does not spread between individuals, it is important to understand how exposure occurs and the common sources to prevent infection [Legionnaires' Disease: A Serious Respiratory Infection and Its Hidden Sources (Arabic)](). ## How Legionella Bacteria Spreads *Legionella* bacteria exist naturally in fresh water, such as lakes and rivers, and can also be found in soil. However, people generally do not contract the disease unless these bacteria grow and spread in man-made water systems [\[1\]](). These systems include hot tubs, fountains, and plumbing systems in large buildings like hotels or nursing homes [\[2\]](). Transmission occurs when inhaling mist or tiny water droplets containing the bacteria, which may come from a shower, hot tub, or air conditioning units in large buildings [\[1\]](). It is very rare to contract the infection by drinking water containing the bacteria, unless the water is accidentally inhaled into the lungs [\[1\]](). ## People Most at Risk Most healthy people who are exposed to *Legionella* bacteria do not get sick. However, certain groups are more susceptible to developing Legionnaires' disease if exposed to the bacteria. These groups include: - People over the age of 50 [\[1\]](). - Current or former smokers [\[1\]](). - People suffering from chronic illnesses such as diabetes or kidney failure [\[2\]](). - People with chronic lung diseases such as Chronic Obstructive Pulmonary Disease (COPD) or emphysema [\[1\]](). - People with a weakened immune system due to illnesses such as HIV or cancer, or those taking immunosuppressive drugs [\[2\]](). - Those who have recently stayed in a hospital or underwent surgery requiring anesthesia [\[1\]](). - Those living in long-term care facilities [\[2\]](). ## Importance of Early Diagnosis and Treatment Symptoms of Legionnaires' disease usually appear 2 to 14 days after exposure to the bacteria [\[1\]](). Common symptoms include cough, high fever, chills, headache, chest pain, shortness of breath, and fatigue. Digestive symptoms such as nausea, vomiting, and diarrhea may also occur, in addition to mental changes like confusion [\[1\]](). Because these symptoms resemble other types of pneumonia, early diagnosis is critical. For diagnosis, a healthcare provider may request a chest X-ray to check for pneumonia, in addition to laboratory tests such as urine or sputum analysis to look for *Legionella* bacteria [\[2\]](). Treatment is with antibiotics, and most people recover, especially if they were in good health when they contracted the disease and received treatment early [\[1\]](). Legionnaires' disease can cause serious and life-threatening complications such as respiratory failure, kidney failure, and septicemia; about 1 in 10 people who contract the disease may die due to complications [\[1\]](). ## Preventive Steps to Reduce Risks Although the disease does not spread from person to person, taking preventive measures to control the growth and spread of *Legionella* in water systems is critical. The risk of contracting Legionnaires' disease can be reduced by: - Regularly cleaning all water-related equipment, such as portable humidifiers, water heaters, air conditioners, and nasal irrigation devices [\[1\]](). - If faucets and showerheads have not been used for a week or more, hot and cold water should be run for at least two minutes before use [\[1\]](). - Avoiding exposure to water sources such as decorative fountains or hot tubs if you are not sure they are well-maintained [\[1\]](). - Using effective water management programs in buildings and equipment prone to the risk of *Legionella* growth and spread [\[3\]](). - Regularly checking the levels of disinfectants and chemicals in hot tubs [\[3\]](). ## Medical references - [Legionnaires' Disease]() - [Legionella Tests]() - [About Legionella Control]() General health education; not a substitute for individualized clinical assessment. Citation URL: https://clinicsjo.com/en/faq/does-legionnaires-disease-spread-person-to-person#answer