What is Lochgoilhead fever?

Lochgoilhead fever is the informal name for an outbreak of Pontiac-fever-type illness traced to a whirlpool spa at a leisure complex in the Scottish village of Lochgoilhead. It was caused by Legionella micdadei, reported in The Lancet in 1989, and everyone affected recovered.

What Lochgoilhead fever is

Lochgoilhead fever is not a separate disease with its own entry in a medical textbook. It is the name that attached itself to one specific outbreak of legionellosis, the family of illnesses caused by breathing in water droplets contaminated with legionella bacteria. The outbreak took place at a leisure complex in Lochgoilhead, a village at the head of Loch Goil in Argyll, Scotland, and the name of the village became the name of the illness in the same way that Pontiac fever took the name of Pontiac, Michigan.

The illness itself was of the mild, non-pneumonic kind. People developed a flu-like illness with fever, headache and muscle aches, but nobody developed pneumonia and nobody died. That pattern, a high attack rate with low severity, is the signature of Pontiac fever, and the later scientific literature treats Lochgoilhead as one of the defining Pontiac fever outbreaks.

What actually happened

The outline is straightforward. A number of people who had used the facilities at a leisure complex in Lochgoilhead became unwell with a sudden flu-like illness. Public health investigators traced the common exposure to a whirlpool spa at the complex. Water from the whirlpool was found to be heavily contaminated with a legionella species, and testing of those affected pointed to the same organism.

The outbreak was written up in The Lancet in 1989 by Goldberg and colleagues under the title "Lochgoilhead fever: outbreak of non-pneumonic legionellosis due to Legionella micdadei", with a follow-up microbiological investigation by Fallon and Rowbotham published in the Journal of Clinical Pathology in 1990, which described the episode as an outbreak of Pontiac fever due to Legionella micdadei associated with use of a whirlpool. Those two papers are the primary sources behind every later account of the outbreak.

Sources: Goldberg DJ and colleagues, The Lancet, 1989; Fallon RJ and Rowbotham TJ, Journal of Clinical Pathology, 1990.

The Pontiac fever link

Legionellosis comes in two main forms. Legionnaires' disease is the serious pneumonic form, which needs antibiotics and can be fatal. Pontiac fever is the mild form: a short, self-limiting flu-like illness with no pneumonia, a high attack rate and recovery within a week without antibiotics. Lochgoilhead fever sits in the second camp. Our page on Pontiac fever sets out the comparison in full, including the incubation periods and attack rates from public health guidance.

One detail makes Lochgoilhead unusual and worth its own page: the organism. Most legionella illness, and most legionella guidance, centres on Legionella pneumophila. The Lochgoilhead outbreak was caused by Legionella micdadei, a different species in the same family. The genus contains dozens of species, several of which can cause illness, and the Lochgoilhead investigation is one of the standard pieces of evidence for that. Control measures do not change by species, because every legionella species depends on the same conditions: warm water, stagnation, nutrients and a way of becoming airborne.

Why a whirlpool was the source

A whirlpool or spa pool is close to a perfect legionella delivery system. The water is held at 30 to 40°C, squarely inside the 20°C to 45°C range where legionella multiplies. The jets and aeration break the water into a fine mist that is inhaled directly by the people sitting in it, and bathers add a constant supply of nutrients. Legionella in hot tubs and spa pools explains why these systems are among the highest-risk water systems there are, and the other bacteria hot tubs carry make the same water a problem even where legionella is absent.

The Lochgoilhead outbreak is a documented example of that chain of failure: warm recirculated water, heavy aeration, many people exposed at once, and a large fraction of them falling ill. Later outbreaks have followed the same pattern, including spa pools that produced both Pontiac fever and full Legionnaires' disease in the same exposed group.

What it means for a duty holder

Three lessons carry over directly to anyone running a spa pool, hot tub or any other aerosol-producing water system today.

• Mild illness is still a failure. Nobody died at Lochgoilhead, but the outbreak proved the whirlpool was broadcasting infectious aerosol. The same water on a different day can produce Legionnaires' disease in an older or immunocompromised bather. The law targets the exposure, not the luck of the outcome.
• It is not only Legionella pneumophila. A control regime designed around one species still works against the others, but only if it is actually run: continuous disinfection, filtration, dilution, cleaning and recorded daily checks.
• The regime now exists in writing. HSG282, the HSE guidance on the control of legionella and other infectious agents in spa-pool systems, sets out the full control regime, and it applies to any business providing a hot tub for others, including holiday lets.

Prevention has not changed since 1989, because the physics has not changed. Keep the water disinfected at the right residual, keep it filtered and diluted, drain and clean on schedule, and record every check. The prosecution record in our legionella enforcement tracker shows what happens when operators skip that work, and a documented risk assessment is where a defensible regime starts.