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Legionnaires’ (LEE-juh-nares) disease is a serious type of pneumonia (lung infection) caused by Legionella (LEE-juh-nell-a) bacteria. Legionnaires’ disease, or Legionellosis, is a severe infection caused by Legionella species, primarily L. pneumophila (New-ma-fa-la). 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, self-limiting, acute illness without pneumonia.
Legionella is a type of bacterium that occurs naturally in fresh water environments and can cause Legionellosis. Legionellosis has two different forms – Legionnaire’s disease and Pontiac fever. Learn more about Legionellosis by visiting the Virginia Department of Health’s Legionella webpage.
The naturally occurring Legionella bacterium becomes a health concern when it begins growing in a human-made building water systems, such as a showerhead, hot water tank or cooling tower. Legionellosis spreads when an individual breathes in contaminated water droplets or accidentally sucks water into the lungs. People do not typically spread Legionnaire’s disease to other people. This infographic from the Centers for Disease Control and Prevention explains how Legionella affects building water systems and people.
Find out more about the disease, how it spreads and who is at risk by visiting the Centers for Disease Control and Prevention.
It’s common to find Legionella species other than Legionella pneumophila in cooling towers and water distribution systems. While there are more than 58 different recognized Legionella species, less than half of those can cause illness in humans. Approximately 25 species are known to be harmful to us, one has been identified as the cause of Legionnaires’ disease. Legionella pneumophila species serogroup 1, 3, 4 and 6 (Lp1, Lp3, Lp4, Lp6) have been linked to disease in humans with L. pneumophila serogroup 1 being the most serious and responsible for the majority of infections.
Lp1 is the primary strain that causes human illness and is estimated to be responsible for causing over 90% of all legionellosis cases. Lp2, and the other strains of Legionella bacteria, are considered to be less pathogenic and less of a concern regarding causing legionellosis disease in humans. However, the presence of these strains of bacteria in cooling tower water is an indication that the conditions for legionella growth are present, and additional investigation and remedial actions should be taken.
In July 2019, the Virginia Department of Health and the Chesterfield County Health District notified Chesterfield County government and Chesterfield County Public Schools of a preliminary report showing that Greenfield Elementary School had tested positive for Legionella bacteria.
Legionella bacteria naturally occurs in lakes and streams, but it becomes a health concern when it begins growing in human-made building water systems, including cooling towers.
Following the report of Legionella at Greenfield Elementary, testing was conducted by the Centers for Disease Control and Prevention (CDC) and the Chesterfield Health District (CHD). CDC/CHD tested five schools and another seven private facility sites. CDC testing found three schools positive for LP1 and one school with an undetermined type of Legionella, which is indicated as 'blue-white Legionella species' on the test results.
In subsequent testing of five more schools by the county, an additional two schools tested positive.
Prior to August 20, a total of seven schools with cooling towers tested positive. Since then, all CCPS cooling towers have been cleaned.
The small case numbers for county and region raise statistical issues concerning accuracy, and thus usefulness, of the rate data.
There are a total of 13 cases in Chesterfield county in 2019, ten cases between May 1st and mid-July. There have been three more cases in the county since Aug 1st:
These final three cases are considered sporadic (appearing without pattern) and are unrelated to the spike in cases noted from May to July that prompted the investigation. The spring-summer cases also demonstrated a cluster pattern suspicious of a common source, which is not true for the most recent three cases. At this point VDH is monitoring trends. VDH expected more cases due to increased surveillance over and above baseline numbers for this time of year.
Source Virginia Department of Health (VDH)
The Virginia Department of Health has been investigating an unusual number of cases of Legionnaires’ disease in the Chesterfield Health District. As of September 19, Chesterfield Health District has no reports of students, staff or parents in any Chesterfield County Public School (CCPS) school having contracted Legionnaires’ disease within Chesterfield County. Thus far in this investigation, there is no link between any CCPS school and those who have contracted Legionnaire’s disease.
County government owns the school facilities as indicated in the Chesterfield County Charter. Chesterfield County Public Schools (CCPS) is responsible for the operations and maintenance of CCPS facilities.
There are a total of 49 cooling towers at 34 schools in the county. There are 5 cooling towers on 5 county-owned buildings.
In addition to six county school cooling towers, several other sites in the county were also tested. These included:
The Department of Internal Audit and the Department of Risk Management will be issuing their reports that are expected by mid-October.
See routine maintenance and information reports.
The county government and school division collaborate on many support services to provide efficient and effective services to county residents and students. Working jointly in these areas permits the county and school system to direct public resources to front line priorities of the community, such as public safety and education. See a list of government and school collaborative services.
The Department of Risk Management assures effective and sustainable management systems are implemented across Chesterfield County and Chesterfield County Public Schools to identify, evaluate, and control operational and organizational risks to minimize potential loss and liabilities associated with our operations and activities. The services they provide include:
There are several guidelines and recommended practices. ANSI/ASHRAE Standard 180-2018 Standard Practice for Inspection and Maintenance of Commercial Building HVAC Systems and ASHRAE Guideline 12-2000 are key reference documents. In addition, the Centers for Disease Control & Prevention and OSHA have a great deal of useful information on their websites under legionnaires.
Best practice indicates that the conditions of all operating cooling towers should be visibly observed and the water treatment control measures monitored monthly, the towers physically cleaned semi-annually, and disinfected quarterly.