In 2017, there were almost 7,500 cases of Legionnaires’ disease reported in the United States, according to the CDC. Additionally, the rate of legionellosis cases reported has increased by nearly five and a half times since 2000. Because the disease is often underdiagnosed, this number is most likely an underestimate of the true number of cases. Legionella is bacteria that is naturally-occurring in fresh water aquatic systems and becomes a risk when it enters human-made water and plumbing systems. It thrives in warm water environments and is known to grow in hot tubs, spas, pools, fountains, ice machines, and faucets.

The Legionella bacteria was first discovered in 1976 in Philadelphia during an American Legion Convention. Many participants at the convention became ill with a type of pneumonia, which was later found to be caused by the respiration and inhalation of water droplets containing the Legionella bacteria.

The respiration or inhalation of water droplets or aerosols containing the bacteria can lead to community-acquired pneumonia, or Legionnaires’ disease along with Pontiac Fever which is a milder form of legionellosis that presents flu-like symptoms. There are over 60 species of Legionella, with six different serogroups that can cause disease in humans but most cases of legionellosis are caused by Legionella pneumophila serogroup 1, the pneumonic form of Legionella.

Environmental Health Significance

Because Legionella is a recently-emerging environmental health issue, the resources and materials available to address the concerns presented by the bacteria are insufficient. The significant increase in reported legionellosis cases over the last two decades results in a demand for more comprehensive public and environmental health programs to target the risks associated with Legionella. In addition, further education and training for public and environmental health professionals around building water systems and premise plumbing is necessary to develop programs for preventing and mitigating these risks.

Role of Environmental Health Programs

In many instances, environmental health programs serve as a nexus - bringing together information from academia, industry, clinicians, and the community to address environmental issues that impact public health. This is especially true with legionella -- where ongoing research, diagnosis, and industry practices evolve daily. 

NEHA in continuing to engage all of these sectors in identifying and developing best practices, impactful partnerships, and applying the latest research.  Our initial scan has identified the following needs and core competencies needed for a well -rounded program:

  • Funding
  • Training & education available to health departments
  • Guidelines for program implementation
  • Standards & policies regulating Legionella
  • Authority to enforce rules and regulations
  • Knowledge of water management plans
  • Outbreak investigation kits (water sampling & testing)
  • Multi-disciplinary team members
  • Collaboration among levels of government & sharing of information
  • Compliance from building owners/managers and facility operators





EH Topics: