Ten cases of Legionnaires’ disease have been confirmed in the northeast quadrant of Chesterfield County since May 1.
Dr. Alexander Samuel, the director of the Chesterfield Health District, said the average number of cases during the summer is three.
Legionnaires’ disease is a type of pneumonia caused by the Legionella bacteria, which is naturally occurring in lakes and streams. The health district said the bacteria becomes a health concern when it aerosolizes — or is converted into small particles that can be transported in the air — into water systems such as cooling towers, which provide air conditioning for large buildings, or into decorative fountains and hot tubs.
People contract the disease by breathing in the bacteria, not by drinking water. The disease can’t be contracted from air conditioning units for homes and vehicles because they do not use water to cool, according to the Chesterfield Health District.
The health district and the federal Centers for Disease Control and Prevention are investigating the recent cases in Chesterfield to identify possible sources of exposure. Samuel said cooling towers are “more than likely” the cause, but he added that it’s possible the health district might never determine a definitive source because the cases have been so spread out.
The disease, which is treated with antibiotics, typically affects adults older than 50; smokers; and people with weakened immune systems, chronic lung disease or other chronic health conditions. All of the cases in Chesterfield have been among “older adults” and people with medical conditions, according to a news release from the health district.
Samuel emphasized that the situation is not a public health emergency or an outbreak. While there is “urgency” to find a source, he said, the risk to residents and visitors is small, and most people exposed to Legionella do not develop the disease.
“Out of an abundance of caution, the health district recommends that individuals who become ill with pneumonia-like or respiratory symptoms, such as fever, chills, cough, shortness of breath, muscle aches and headache promptly seek medical care,” Samuel said in the news release.
Legionnaires’ disease has increased significantly in the state and nationally. In Virginia, there were 236 cases in 2018, compared with 78 in 2010.
Samuel said it’s not clear what factors have contributed to the increase. It could be because of an aging, and more susceptible, population, he said, or because of more rigorous testing or greater amounts of Legionella in the environment.