Legionellosis is caused by bacteria called Legionella. The disease has two different forms. Legionnaires’ disease is the more severe form of infection that causes pneumonia. Pontiac fever is caused by the same bacteria, but is a milder illness without pneumonia. The disease got its name after a group of people attending a convention of the American Legion in Philadelphia in 1976 developed pneumonia. Although the Legionella bacteria were around before 1976, scientists had never been able to find these bacteria in an ill person’s lungs before that time.

Reports of legionellosis cases and outbreaks are increasing in the United States and in Virginia. Legionellosis is caused by breathing in small water droplets containing Legionella bacteria. Outbreaks are commonly associated with buildings or structures that have complex water systems, such as hotels and resorts, long-term care facilities, hospitals, and cruise ships.

Antibiotics are used to treat Legionnaires’ disease. There is no vaccine to prevent legionellosis, but the presence of Legionella bacteria can be reduced by properly maintaining water systems where the bacteria grow (such as heating, cooling, and plumbing systems).

Chesterfield County Situation

The Chesterfield Health District (CHD) investigation of an increase in cases of Legionnaires' disease associated with the northeast quadrant of Chesterfield County is complete. Between May 1 and July 31, 2019, there were 10 confirmed cases among older adults and people with certain medical conditions.

Testing Sites and Legionella Environmental Testing Results - last uploaded September 12, 2019

Because Legionella is commonly identified in building water systems and devices that are not adequately maintained, it is not unexpected that multiple positive sites were identified in this investigation. Even though a definitive link could not be made between an individual case and a specific exposure source, when Legionella is identified, it is essential to implement plans to remediate these sources and ensure proper maintenance moving forward.

Press Release on Legionellosis

This investigation is complete; as such, these data will no longer be regularly updated.