What is the Legionella Antibodies test?

The Legionella Antibodies blood test detects antibodies produced by the immune system in response to infection with Legionella bacteria, most commonly Legionella pneumophila. These bacteria are found in water systems such as cooling towers, air-conditioning units, hot tubs and plumbing systems.

When a person inhales aerosolised water contaminated with Legionella, it can cause Legionnaires’ disease, a potentially severe form of pneumonia, or a milder illness known as Pontiac fever. Antibodies typically develop after infection and can persist for months or years.

This test is mainly used to assess previous or recent exposure, particularly when respiratory symptoms or epidemiological risk factors are present.

Why do I need a Legionella Antibodies test?

Legionella infection may not always be diagnosed during the acute phase. Antibody testing can help support diagnosis when symptoms are prolonged or when exposure is suspected.

You may need a Legionella Antibodies test if you:

• Have had pneumonia or severe chest infection
• Experience persistent cough, fever or breathlessness
• Were exposed to contaminated water systems
• Work in high-risk environments (hotels, hospitals, construction)
• Were involved in a known Legionella outbreak
• Have unexplained respiratory illness
• Need retrospective infection assessment

Symptoms associated with Legionella infection include:

• High fever
• Cough
• Shortness of breath
• Muscle aches
• Headache
• Confusion (in severe cases)

Benefits of the Legionella Antibodies test

• Identifies exposure to Legionella bacteria
  Detects immune response to infection.
• Supports investigation of atypical pneumonia
  Useful when standard tests are inconclusive.
• Helpful in outbreak investigations
  Assists epidemiological assessment.
• Clinically recognised diagnostic marker
  Used in infectious disease evaluation.
• Useful when acute testing was missed
  Detects past infection.
• Simple blood test
  No respiratory samples required.
• Supports occupational health screening
  Relevant for high-risk workplaces.
• Guides further diagnostic testing
  Indicates need for additional confirmation.

Step by step – how the test works

You can access Legionella Antibodies testing UK-wide through two options:

1. Clinic appointment
   Attend your nearest UK clinic, where a healthcare professional will take your blood sample.
2. At-home or hotel visit (£60 extra)
   A qualified phlebotomist comes to your home or hotel for sample collection.

Your sample is analysed in an accredited UK laboratory, and results are delivered securely.

Your results explained

Negative Legionella antibodies

No evidence of previous Legionella exposure.

Typical UK interpretation:

• Legionella antibodies: Negative

Positive Legionella antibodies

Suggests past or recent exposure to Legionella bacteria.

Typical UK interpretation:

• Legionella antibodies: Positive

Rising antibody levels (paired samples)

A significant rise between two samples may indicate recent infection.

Results should be interpreted alongside symptoms and exposure history.