Legionella: Deadly virus first identified when it struck conference

There may have been a vague understanding of a rare condition which strikes unlucky holidaymakers, but certainly nothing to worry about in everyday life.

Today, of course the outbreak gripping the city has ensured that the man on the street is fast becoming an expert in the waterborne virus.

But where did it come from, is it becoming more common, and what more can we do to prevent future outbreaks?

Surprisingly perhaps, legionnaires’ is a relatively new discovery.

It was first identified in 1976 when an outbreak of pneumonia occurred among delegates attending a convention of the American Legion at the Bellevue-Stratford Hotel in Philadelphia. In all, 234 people became ill and 34 died, most of them elderly.

But it was not until the following January that the cause was identified – a previously unknown strain of bacteria which was then named legionella.

The bacteria is often found in natural water sources such as rivers and ponds, but these are not a source of infection. Sufferers are instead usually struck down after breathing in small droplets of contaminated water from sources such as air conditioning cooling towers, jacuzzis and sprinklers which have not been sufficiently cleaned.

Some people who are exposed are unaffected, while others will contract a milder version of the disease known as Pontiac fever, which is often mistaken for flu.

Around 40 people a year contract legionnaires’ disease in Scotland, but it is only when several cases are clustered together that public health officials consider it an outbreak and launch a large-scale response. In Edinburgh’s current scare, it was only when the third and fourth cases were confirmed on Sunday that the Incident Management Team was called together to coordinate its actions, in the anticipation that the number of cases was likely to continue rising.

Legionnaires’ expert Allen Wilson, who runs the consultancy Studies in Work, says it is largely a disease of recent decades. “It existed before 1976 but was probably diagnosed as pneumonia, which it is a form of.

“Ten years prior to that in Pontiac, Michigan, there was a smaller outbreak, and it was self-limiting so they didn’t do much research on it.

“We’ve got greater awareness of legionnaires’ disease now, but it’s also very much a 20th- century disease.

“It wasn’t common until we started using water between 20 and 45 degrees. We introduced showers, we introduced jacuzzis. Where you’ve got water at body temperature and because you’re agitating it, you’re also creating respirable droplets. Cooling towers – again, it’s the last 40 years they’ve been brought in.”

Fears have been raised that cutbacks are leading to less stringent checks in both the public and private sector, increasing the risk of outbreaks.Leading bacteriologist Professor Hugh Pennington has called for an overhaul of the regulation and monitoring systems: “A situation like this relies on the expertise of an environmental health officer [EHO] who knows through experience which places might be likely sources,” he says.

“In many cases EHOs are not being replaced by councils as their budgets are reduced. I have had a concern about this for quite some time.”

Mr Wilson says there is also a risk from people turning down the temperature on water systems for financial or environmental reasons. “One way of thermally sterilising is to keep a water temperature up above 60 degrees.

“At 50 degrees, you’ll kill 90 per cent of the legionella in two hours.”

The peak in cases in the UK is usually during the summer months, which is partly because higher temperatures mean water is more likely to warm to temperatures which encourage legionella bacteria to thrive, and partly because of the number of people bringing the infection back from holidays abroad.

The current outbreak is not the first in Edinburgh – nor is it the first to see the spotlight turned on Burton’s biscuit factory on Sighthill Industrial Estate. In 1994, an outbreak saw one man dead and five left in intensive care, with a further eight suspected cases. Burton’s, British Telecom and NE Technology were all described as having unsatisfactory management procedures after they were examined during efforts to find the source, though no link to the outbreak was ever proven. At the time the outbreak was linked to a cooling tower at Heriot-Watt University’s Riccarton campus, but the university said today that no link had ever been proven, and no action was taken against it.

PREVIOUS OUTBREAKS

1. Barrow-in-Furness, Cumbria

Britain’s biggest outbreak of legionnaires’ disease in August 2002 saw 180 people fall ill and seven die as a result of an outbreak at the council-owned arts and leisure centre Forum 28 in Barrow-in-Furness. It was traced to an air-conditioning unit which was not adequately cleaned or monitored.

Although the confirmed cases stood at 180, it is thought that around 2500 could have been affected by the bug, most of them with the milder but related Pontiac fever.

Barrow Borough Council became the first public body to face corporate manslaughter charges, but the council and its design services manager Gillian Beckingham were acquitted. They were, however, both convicted and fined under the Health and Safety at Work Act.

2. Bovenkarspel, Netherlands

In 1999 there were at least 32 deaths linked to the annual Westfriese Flora flower exhibition in Holland, and more than 200 people taken ill.

When a large number of patients with flu and pneumonia symptoms reported to Westfriese Hospital in Hoorn, the Amsterdam Academic Medical Centre was called in and experts found they were suffering from legionnaires’.

Interviews with the patients quickly established that they had all visited the flower show. After tests on a variety of possible outlets, it was concluded that the most likely source was a whirlpool bath installed in one of the exhibit halls. At the time, it was the largest number of deaths due to legionnaires’ in a single incident since the original 1976 Philadelphia outbreak.

3. Toronto, Canada

between September 1 and October 13, 2005, around 135 people contracted legionnaires’ disease and 23 people died. Among them were residents, visitors, staff members and neighbours of Seven Oaks Home for the Aged in the Scarborough area of Toronto.

Legionnaires’ was initially ruled out and tests were then carried out for Sars, bird flu and influenza. However, when cultures taken from autopsies were grown and tested, they proved positive for legionnella.

When the source of the outbreak was traced to the air conditioning cooling tower on the nursing home’s roof, many of the victims launched a class action law suit against Toronto Public Health, the City of Toronto’s Homes for the Aged Division and the home.

4. Calpe, near Alicante, Spain

In January and February this year, more than 20 people were thought to have been infected while staying at the Diamante Beach Hotel in Calpe, Costa Blanca.

Among those affected were British pensioners travelling with Saga Holidays, three of whom died. When the company was informed on January 14 that one of its clients was suffering from legionnaires’ disease, it flew an expert to Spain, and after water testing moved holidaymakers to a different hotel.

The hotel was closed in February, but it was later reported that health authorities had first been notified of a case of the disease in mid-December, when a Spanish guest at the hotel was diagnosed. Two weeks later, on December 27, a waitress at the hotel was also struck down. Two of the British pensioners who died in January were initially thought to have suffered heart attacks and only discovered during postmortems to have been suffering from legionnaires’ disease.

5. Stafford, England

PRIOR to Barrow-in-Furness, the UK’s biggest outbreak was at Stafford Hospital in 1985. Estimates of the exact death toll vary from 22 to 39, with up to 163 people infected.

The source of the infection was traced to a leaking seal in the air-conditioning cooling tower on the roof of Stafford District Hospital.

Investigations traced the infection to the outpatients department and epidemiological surveys showed that staff working in the affected area had antibodies to the disease.

The large number of people affected was thought to be because the outpatients department had such a large number of people from the risk groups and their friends and family passing through. Cases were initially treated as flu because they appeared in such a scattered fashion, not typical of legionnaires’ disease.

6. Melbourne, Australia

In 2000, the newly-opened Melbourne Aquarium was the site of a major outbreak caused by an infection in its cooling tower.

Four years after the outbreak, 144 people won compensation at a civil trial.

A spokesman for the group said the outbreak had affected more than 170 people, and four had died directly from the disease, with another 12 of the class action members since dying from conditions allegedly related to the disease.

All victims of the outbreak had visited or were near the aquarium during April 2000.

449 confirmed cases in largest global outbreak

THERE have been many other serious outbreaks.

The world’s largest was in Murcia, Spain, in 2001, and saw more than 800 suspected cases, of which 449 were confirmed.

Four people died. It is thought that the infection came from the cooling towers at a city hospital.

Among other large outbreaks was one originating in Frederikstad, Norway, in 2005.

It was attributed to an “air scrubber”, used to remove polluting particles or gases from industrial exhausts in a factory and left ten people dead and 56 ill.

In New Brunswick, in the US, St Peter’s University Hospital became the source of an infection, with two patients dying and eight others contracting the disease. Chlorination in the hospital’s water system is thought to have dropped below effective levels.

In an outbreak in South Wales in 2010, two people died and around 22 were infected and required hospital treatment.

The source was never conclusively traced, but the infection was thought to have come from cooling plants on one of a number industrial plants clustered around the Heads of the Valleys corridor.

In April and May of this year, Auckland in New Zealand was shock treating large numbers of cooling towers as the disease claimed two lives and infected 16 people.