Legionellosis (Legionnaires’ Disease)

Reportable by Providers and Laboratories

About this Reportable Disease

Infectious agent: Legionella bacteria, primarily Legionella pneumophila

Description of illness: Illness is classified as either Legionnaires’ disease or Pontiac fever. Symptoms of Legionnaires’ disease include cough, shortness of breath, fever, muscle aches and headache. Pontiac fever is milder than Legionnaires’ disease; primary symptoms are fever and muscle aches

Interactive Disease Data

Laboratory Reporting for this Disease

Legionella species

TEST NAME	Legionella species
DISEASE/DISORDER	Legionnaires' Disease, Pontiac Fever, Legionellosis
ALTERNATE NAME(S)	Legionella culture
METHODOLOGY	Culture
SPECIAL INSTRUCTIONS	Isolate submission is REQUIRED for laboratories. Clinical specimens MUST be frozen (-15 C or lower) within 48 hours of collection.
ORDERING INFORMATION	Lab Web Portal

Specimen Requirements

Patient Preparation	None
Specimen Collection	Clinical Specimens - Lower respiratory sources such as bronchoalveolar lavage, bronchial aspirate/brushing/lavage/washing, tracheal/endotracheal secretions/aspirate, or sputum collected in a sterile container - Fresh tissue or biopsy sources such as lung, pleura, heart valve, or pericardium collected in a sterile container Isolates -Pure cultures from normally sterile sites on Buffered Charcoal Yeast Extract (BCYE) or equivalent media
Specimen Labeling	Specimen should be labeled with at least two unique patient identifiers along with specimen source and match accompanying test order.
Specimen Processing	None
Specimen Storage and Preservation	Clinical specimens should be stored at 2-8°C for no more than 48 hours. Specimens that are not transported/tested within 48 hours should be frozen at (-15)°C or lower. Isolates should be stored under ambient conditions.
Specimen Transport	Clinical specimens - If shipment will arrive within 48 hours of collection, ship overnight at 2-8°C with cold packs. - Frozen specimens should be maintained at (-15)°C or lower and shipped overnight on Dry Ice. Isolates - Ship at ambient temperature. - Do not send refrigerated or frozen All infectious substance shipments must conform to U.S. Department of Transportation (DOT) Hazardous Materials Regulations (HMR 49 C.F.R. Parts 171-180).
Specimen Acceptability and Rejection	Urine is not accepted for antigen testing. Specimens that do not meet all specimen requirements will be rejected.
Testing Location	Nashville

Laboratory Reporting

Reporting requirements apply to all laboratories located within Tennessee, as well as laboratories outside of Tennessee that test residents of Tennessee, including laboratories located within healthcare facilities. Healthcare providers and laboratories in the same healthcare facility both have a duty to report. The type of organisms and analytes laboratories must report to TDH for 2026 are indicated, and there are several ways laboratories can report results to TDH.

Manually report results to TDH by faxing or mailing a completed PH-1600 form to your local health department, or faxing to the state health office at (615) 741-3857
Automatically submit results to TDH via electronic laboratory reporting (ELR), which automates the process of sharing data with TDH using interoperability standards.
- See the ELR Onboarding Handbook for details on the onboarding process, checklist, frequently asked questions, business rules, message format, and vocabulary.
- To initiate the ELR onboarding process with TDH, register in the Trading Partner Registration (TPR) system TPR provides documentation for Promoting Interoperability (PI) attestation and milestone letters to document onboarding progress. Contact MU.Health@tn.gov for assistance.
Submit online via NBS. NBS is TDH's reportable disease system. To request an NBS account for reporting Complete this user survey to request an NBS account for reporting.
Blood lead levels can be sent via fax ( (615) 741-3857), entered online, or reported using the instructions at this link.

Information about this Reportable Disease for Healthcare Providers

Clinical Summary

Legionellosis includes Legionnaires’ disease (pneumonia) and Pontiac fever (self-limited febrile illness without pneumonia) caused by Legionella; Legionnaires’ disease cannot be reliably distinguished clinically or radiographically from other pneumonias, so diagnostic testing is important.
Clinical evaluation should include exposure history (e.g., recent travel, overnight stays outside the home, healthcare facility stays, or potential building water exposures) and severity assessment to guide testing and treatment.
Diagnostic testing commonly includes urinary antigen testing and culture (culture supports species/serogroup identification and outbreak investigations).
Treat Legionnaires’ disease with appropriate antibiotics and provide supportive care; Pontiac fever does not require antibiotics. Legionellosis is reportable in Tennessee, supporting surveillance and outbreak response.

Clinical Links & Info

Clinical information about this disease | CDC

Disease Surveillance and Trends | CDC

Review the case definition | CDC

Access the case report form (2023) | TDH

Healthcare Provider Reporting

Healthcare reporting requirements apply to all providers located within Tennessee, as well as providers whose patients reside in Tennessee.

Providers must report cases of all diseases and conditions listed through one of these methods:

• Mail or fax a completed PH-1600 form to your local health department or fax to the state health office at (615) 741-3857

• Send automatically via electronic case reporting (eCR). See this TDH webpage for more information on eCR, register at the Trader Partner Registration website, or contact MU.Health@tn.gov for assistance.

• Submit online via NBS. NBS is TDH's reportable disease system. To request an NBS account for reporting Complete this user survey to request an NBS account for reporting.

• Blood lead levels can be sent via fax ( (615) 741-3857), entered online, or reported using the instructions at this link.

Information about this Reportable Disease for the Public

What Is It

Legionellosis is an infection caused by Legionella bacteria and includes two illnesses: Legionnaires’ disease (a serious type of pneumonia) and Pontiac fever (a milder, flu-like illness).

Who Is at Higher Risk

Risk is higher for older adults, people with weakened immune systems, and people with certain underlying health conditions. Exposure can also be higher for people who spend time in settings with complex water systems (including some healthcare and long-term care facilities).

Signs and Symptoms

Legionnaires’ disease can cause pneumonia symptoms such as cough, shortness of breath, fever, muscle aches, and headaches, while Pontiac fever is milder and often includes fever and muscle aches without pneumonia.

How It Spreads

People usually get infected by breathing in small water droplets (mist) that contain Legionella from contaminated water sources (for example, parts of building water systems). Legionellosis generally does not spread from person to person.

Prevention

Prevention focuses on managing building water systems to reduce Legionella growth and spread. CDC provides guidance on water management programs and recommendations for water management in healthcare and other settings.

Legionella and Waterborne Illness Resources

External link and accessibility notice: Some links below take you to websites outside the Tennessee Department of Health (TDH). TDH does not control the content, privacy policies, or accessibility of external sites.

General Prevention

Waterborne Diseases (TDH webpage)

Surveillance and Outbreak Response

TDH Legionellosis Surveillance and Outbreak Response Toolkit (SharePoint folder)

Questionnaires and Investigation Tools

Guidance for Healthcare Settings

This Page Last Updated: March 25, 2026 at 10:03 PM