Legionnaires Disease New Zealand

During 1995, 76 cases of legionellosis (44 confirmed and 32 probable) were identified in New Zealand, a rate of 2.3 per 100 000. Only 33 (43.4% ) of these cases were notified. Rates of disease were highest in the Canterbury, Manawatu, Wellington, and Wairarapa Health Districts. Incidence was higher among males and among people over 50 years of age. Legionella pneumophila, L. longbeachae and L. micdadei were the most common species detected. It is not clear whether the wide variation in disease rates seen throughout New Zealand represents differences in incidence or in clinical and laboratory practice. Detection of cases and swift notification is important if common source outbreaks are to be recognised and controlled.

Legionellosis is an important cause of community-acquired pneumonia (CAP) worldwide, though the reported incidence varies widely between countries. 1,2,3 Common source outbreaks of infection have also been frequently described. 4,5 In New Zealand, the incidence of legionellosis appears to have been generally rising in recent years, and the reported incidence is high relative to other developed countries. 6 Most cases appear to occur sporadically, with only one outbreak 7 and one cluster of two cases 8 identified since testing for Legionella began in 1980.

This article briefly reviews the epidemiology of legionellosis in New Zealand in 1995.

Surveillance of legionellosis in New Zealand is based on both notification and laboratory reporting. Legionellosis is notifiable to the medical officer of health, and notification data are collated by ESR, on behalf on the Ministry of Health, at the national level. In addition, laboratories are encouraged to forward serological specimens and Legionella isolates to ESR.

The diagnosis of legionellosis requires laboratory confirmation. Confirmation is by isolation of Legionella, or demonstration of the organism by direct fluorescence assay (DFA) in respiratory secretions, pleural fluid or lung tissue. The diagnosis is also considered confirmed if there is a fourfold or greater increase in titre to ³256 between acute and convalescent sera. ESR reports cases as ‘probable’ when a patient with a recent history of pneumonia has a stable convalescent Legionella titre of ³512.
Specimens suitable for culturing are plated on three Legionella media (BCYE, BMPA and GVPC).
These specimens are also routinely tested by DFA. For serological testing, ESR uses the indirect immunofluorescence assay (IFA) with a battery of the 26 most prevalent Legionella species/serogroups.

In 1995, 76 cases of legionellosis (44 confirmed and 32 probable) were detected by laboratories in New Zealand, giving a national rate of 2.3 per 100 000. Of these cases, only 33 (43.4%) were notified to the medical officer of health. Seventy-three cases were confirmed by serology and three by isolation.

In 1995, there were far fewer cases than were reported in 1994 (121), a change from the trend of increasing incidence evident since 1990 (Figure 1).
Areas reporting more than the average rate of legionellosis in 1995 were Canterbury (6.9 per 100 000), Manawatu (6.1), Wellington (5.2), Wairarapa (5.1), West Coast (2.9), and Southland (2.5). No cases were reported in the Eastern Bay of Plenty, Rotorua, Gisborne, Taupo, Hawkes Bay, Ruapehu, Wanganui, or Nelson-Marlborough Health Districts.
The incidence of legionellosis was higher among males and people over 50 years of age (Figure 2). Two fatalities were identified among the 33 notified cases, a case-fatality rate of 6.1%.
The causative species was determined by serology or isolation in 60 % of cases. The most common species were L. pneumophila, L. longbeachae, and L. micdadei. In the remaining 40% of cases, a serological response to two or more antigens was detected.
While responses to more than one antigen can be the result of cross-reactivity, cases of infection with two Legionella species have been reported in New Zealand. 8

Discussion
The true incidence of legionellosis is difficult to assess from current surveillance data. A recently published New Zealand review referred to Legionella as a rare cause of CAP. 9 The results of a CAP study conducted at Waikato Hospital agreed with this view. 10 However, a CAP study based in Christchurch Hospital found that 11% of CAP cases were caused by Legionella species. 11 It is difficult to know whether these apparent regional differences reflect genuine variations in the incidence of legionellosis or differences in clinical and laboratory practice. If the rate of disease seen in Canterbury in 1995 applied throughout New Zealand, then the national total of cases would be approximately 250 instead of the 76 which were actually detected.
Correct diagnosis of patients with legionellosis has implications for their management and outcome. All cases of CAP which require admission to hospital should be investigated for evidence of legionellosis. A recently developed method for detecting Legionella DNA in urine and serum by polymerase chain reaction is probably the most rapid, specific, and sensitive method of laboratory diagnosis. 12 However, since this PCR technique is not yet widely used in clinical laboratories, the optimal testing method is culture or DFA of respiratory specimens. 13 As respiratory specimens are often not produced by patients with Legionella infection, serological tests on acute and convalescent sera should be performed. Swift notification of legionellosis cases to the medical officer of health is essential if common source outbreaks are to be identified and controlled. Notification also assists in better defining the epidemiology of this disease in New Zealand. Acknowledgement: Dr Steve Chambers, Canterbury Health, for helpful comments on the draft.

References

1 Friis-Moller A, Rechnitzer C, Black FT, et al. Prevalence of Legionnaires’ disease in pneumonia patients admitted to a Danish department of infectious diseases.
Scand J Infect Dis 1986; 18: 321-8.
2 Fang GD, Fine M, Orloff J, et al. New and emerging etiologies for community- acquired pneumonia with implications for therapy.
Medicine 1990; 69: 307-16.
3 Joseph CA, Hutchinson EJ, Dedman D, et al. Legionnaires’ disease surveillance: England and Wales 1994.
CDR Rev 1995; 5: R180-3.
4 Mahony MC, Stanwell-Smith RE, Tillett HE, et al. The Stafford outbreak of Legionnaires’ disease.
Epidemiol Infect 1990; 104: 361-80.
5 Colville A, Crowley J, Dearden D, et al. Outbreak of Legionnaires’ disease at University Hospital, Nottingham. Epidemiology, microbiology and control. Epidemiol Infect 1993; 110: 105-16.
6 Chereshsky A, Bettelheim KA. Serological studies of legionellosis in New Zealand.
Israel J Med Sci 1986; 22: 737-9.
7 Mitchell P, Chereshsky A, Haskell AJ, et al. Legionellosis in New Zealand: first recorded outbreak.
NZ Med J 1991; 104: 275-6.
8 Cluroe AD. Legionnaires’ disease mimicking pulmonary miliary tuberculosis in the immunocompromised.
Histopathology 1993; 22: 73-5.
9 Roberts S, Thomas M. Antibiotic use in pneumonia.
New Ethicals 1996: 33; 31-5.
10 Karalus NC, Curson RT, Leng RA, et al. Community-acquired pneumonia: aetiology and prognostic index evaluation.
Thorax 1991; 46: 413-8.
11 Neill AM, Martin IR, Weir R, et al. Community-acquired pneumonia: aetiology and usefulness of severity criteria on admission. Thorax. In press.
12 Murdoch D, Walford E, Schousboe M, et al. Detection of Legionella DNA in urine and serum samples from patients with pneumonia by polymerase chain reaction. Clin Infect Dis. In press.
13 Bartlett JG, Mundy LM. Community-acquired pneumonia.
N Engl J Med 1995; 333: 18-24.

Annette Chereshsky, Scientist;
Michael Baker, Public Health Physician;
Sarah Hopkirk, Medical Laboratory Scientist,
ESR Communicable Disease Centre

******** ......In June 1985 six men resident in a long stay villa at a psychiatric hospital near Wellington developed acute respiratory illness within five days of each other, samples from the men were not collected until the convalescence period, it was noted that in each case there was evidence of infection with Legionella pneumophila. (Chrisp, New Zealand medical J March 1987)

The first recorded outbreak of Legionnaires Disease in New Zealand was in christchurch in 1990, in a new seven storey office building. (Mitchell, New Zealand Medical J 1991 Volume 104 July No 915)

Three cases of Legionellosis caused by Legionella pneumophia serogroup 6 are reported, and a review of similar cases in New Zealand in 1982, Legionellosis appears to be more common in New Zealand than previously thought, In 1982 50% of reported cases occurred in Wellington. (McKeage, New Zealand Medical J 1984 97 213-215)

A 59 year old port employee was admitted to Wellington Hospital in 1979, Legionella pheumophilla was demonstrated, This is the first case of Legionella disease reported in New Zealand. (Holst, New Zealand Medical J 1980 May 339-340)

Fatal legionellosis from gardening (Kingston, New Zealand Medical J 1994 111 March 23)

An unusal legionellosis case yeilds the first New Zealand isolation of Legionella dumoffi. (Badham, New Zealand Medical J 1985 March 27 204)

Sick building disease strikes police officers

Three police officers have been struck down with legionnaires' disease, contracted at the Counties-Manukau headquarters building which is now under investigation by the Labour Department.

About 180 staff continue to work at Harlech House in Otahuhu despite police headquarters accepting the building's water tower air conditioning system was to blame for the trio contracting the potentially fatal disease.

Staff are unhappy that the building dangers were identified in 2000 - but just three months ago a positive test was again recorded at the station.

It is understood two of the officers received secret payouts to prevent employment court action. One of those officers has since quit.

Police Association vice-president Richard Middleton confirmed the three cases, saying the officers had suffered pneumonia-like illnesses.

They contracted legionnaires' disease - caused by inhaling legionella bacteria from a water source - from the air in the building.

Middleton said the association had been fighting to get police headquarters to accept responsibility since problems first emerged in 2000, when two officers fell ill.

"It wasn't until last year that there was an acknowledgment by the department that the disease was contracted through the building," he said.

"There's a massive loss of confidence by staff there in the ability for the department to resolve the matter once and for all."

A third officer had been diagnosed with the disease in the last six months, Middleton said.

It is understood tests have revealed the presence of legionella bacterium in at least one part of Harlech House - a bathroom shower-head.

One officer has quit, one was undergoing rehabilitation and the third had been transferred to another building, Middleton said.

"Their immediate needs have been looked after, although it took some time for that to happen.

"This matter has been extremely frustrating but we have now moved on from there."

An Occupational Safety and Health spokeswoman confirmed the department was investigating building safety, with a report due in about six weeks.

Counties-Manukau district commander Ted Cox, who works at Harlech House, said the health and safety issues were being addressed by a working party comprised of professors, a doctor and building safety representatives.

The recommendations of a hygiene safety report had been implemented and the building was tested every month. The working group, which OSH was also involved with, would review the health of current staff, Cox said.

Police bought Harlech House from the Inland Revenue Department in 1997 for more than $8 million.

The Police Association says South Auckland police are furious at being exposed to the risk of Legionnaires disease.

Nearly 200 staff are being relocated from the Counties Manukau District Headquarters after an expert declared the building unsafe.

Six staff have got Legionnaires since it was discovered in the building's air conditioning four years ago.

The association's national vice president, Richard Middleton, says the association had asked police managers to eliminate the risk right from the start.

He says it is unacceptable that the management tried to minimise the risk instead.

One police officer battling the debilitating lung disease says it is a tragedy the problem wasn't fixed earlier.

Senior Sergeant Dave Anstiss, who tested positive three years ago, says police managers left it far too late to evacuate.

Anstiss says five of his colleagues got sick after a device designed to fix the problem was fitted in the building's water cooling tower.

He believes more cases have yet to come to light because every police officer in the district has spent time in the building's training division.

Two new cases of legionnaires disease have been confirmed at Counties-Manukau police headquarters.

The disease was discovered at Harlech House, where the police are located, three years ago.

Six people have now contracted legionnaires, two in the past few days.

Their condition is not considered serious.

Superintendent Ted Cox says despite precautions taken when it was discovered three years ago, the two new cases mean the building must be evacuated.

He says police are working closely with other agencies to ensure the safety of police staff.

Superintendent Cox says police headquarters will be relocated until the building is safe to return to.

He says police have been working with medical experts from Auckland University, who have advised them to move for their staff's safety.

Superintendent Cox says police headquarters will move on Monday morning.

Note: There will be no follow up interviews with either Dr Brieseman or Dr Humphrey until there is more information to hand. Media will be advised of this as soon as practicable.

The spatial relationship of Legionnaires Disease cases in Christchurch suspected from the case control study carried out by the Canterbury District Health Board last weekend has now been supported by the second arm of the scientific study.

Medical Officer of Health Dr Alistair Humphrey said that the spatial relationship of the cases have been defined in five different ways and each time these have centred on the south west of the city.

“There are 35 cooling towers located within the most significant clusters but until we receive microbiological results from all of them we cannot exclude the fact that there may be more than one potential source.”

“Moreover, since cooling towers can infect each other no single tower can be identified as the root cause of this outbreak.” Dr Humphrey said.

The study had been analysed by a team of scientists in Wellington who had prepared a detailed report.

‘The report identifies that the clusters concentrate on an area emanating outwards in a funnel shape from the southwest in a north-easterly direction.’

‘The study has taken into consideration the prevailing wind direction over the course of the outbreak.”

Unfortunately, the small number of cases means that the clusters are still only supportive of the theory, as the cluster formation is not statistically significant.

Dr Humphrey said that he is satisfied that all companies with positive results so far have cooperated with the investigation team.

“I am satisfied that all of the cooling towers positively identified so far have taken appropriate action and do not constitute a public health risk.”

Some of these companies are working with the industry groups, Christchurch City Council, the District Health Board and others to develop stricter protocols to monitor and treat cooling towers.

“This is an essential step in preventing this kind of Legionnaires outbreak in the future,” said Dr. Humphrey.

COMMUNICATIONS

Clear Lessons to be Learnt from Outbreak of Legionella in Christchurch

The Canterbury District Health Board has today completed its checks on more than 80% of the cooling towers in Christchurch. The results show that the public risk following the recent outbreak of Legionnaires Disease has now been effectively dealt with.

Medical Officer of Health Dr Alistair Humphrey said 139 cooling towers had been tested with 115 confirmed results.

‘The results show that there are now no towers with results above 100 colony infecting units (cfu) which is well below the 1000 cfu considered to be dangerous.

Dr Humphrey said that when the Health Board started its checking regime shortly after the outbreak earlier this year, four companies volunteered positive results. Only one of the four had a result that showed the same strain of legionella that had been discovered in the people who had been diagnosed in this outbreak. This was a cooling tower located close to the centre of the disease cluster.

‘The company contacted us as soon as they had their results and were very quick to advise their staff and immediately take the remedial action we recommended.’

‘In doing so, they acted very responsibly and we commend them for being so prompt even though the high readings they had did not correspond with the outbreak of the disease.’

Dr Humphrey said there were clearly lessons to be learnt from the outbreak in Christchurch, which had seen 19 people diagnosed with Legionnaires Disease and resulted in three deaths.

‘Our concern has always been for public safety, and we have been working with the cooling tower testing companies, the laboratories who test for results, the City Council and other members of the industry sector to look at what protocols can be introduced to prevent the spread of Legionnaires Disease from cooling towers. This is important not only for Christchurch but for any other city in New Zealand.’

Dr Humphrey said it had taken several weeks to get the test results and during that time the Health Board had conducted a scientific study interviewing the people diagnosed with Legionnaires Disease and the families of those who died, as well as others of similar age and gender to get a more informed opinion of what had happened.

‘The study demonstrated a probable spatial relationship between the main cluster of people with the disease and the location of a single high result last April. Unfortunately, many companies did not test their cooling towers around the time of the outbreak including the one that had the high result.’

Dr Humphrey said that the DHB would get the results back from all the 139 cooling towers in Christchurch and he and his team would continue to work closely with the City Council to get these as soon as possible.

‘The last case of Legionnaires Disease was notified on 16 August and as times goes by we are increasingly confident that this outbreak is over.’

Cluster Statistics of Legionella Outbreak in Christchurch 727KB PDF Format

Ends.

Please note there is no further comment at this time.

Vivienne Allan
Communications Manager

COMMUNICATIONS

CDHB Releases Water Cooling Tower Results

Today the Canterbury District Health Board has released the name of the business in Christchurch whose water cooling tower exceeded the recommended guidelines for legionella in April this year at the start of the outbreak of Legionnaires Disease.

The company has worked with health authorities, the Dept of Labour through OSH, and the Christchurch City Council to shock treat and test its tower on a regular basis with results that are now well below the recommended danger level.

‘The outbreak of Legionnaires Disease in Christchurch earlier this year prompted a large-scale checking system to be put in place to not only identify all the cooling towers in the city, but to simultaneously survey the people and their families who had been diagnosed with Legionnaires Disease to try and draw some scientific conclusions as to location, strain and cause,’ said the CDHB’s Interim Chief Executive Dr Karleen Edwards.

‘It was a very protracted process complicated by the fact that there was no single database of water cooling towers.’

‘The laboratory results of tests taken from patients was consistent with a strain of Legionella linked specifically to water cooling towers which was why we focused on the towers as the probable cause.’

Dr Edwards said of the early results that came through, one cooling tower belonging to Ravensdown Ltd had a high level of colony forming units (cfu) of the same strain of Legionella identified later in all 19 cases.

Of 139 water cooling towers in the city, with more than 80% of the test results now back, only four had tested positive, of which three were of a different strain of Legionella and at a level of cfu that was not high or moderate.

‘Ravensdown has acted very responsibly and we commend them for their swift action at the outset in volunteering their results and working with us to shock treat and test their tower. They advised their staff and have conducted their own research into what has happened.’

‘The DHB’s concern has always been for public safety and to ensure that correct and accurate information has been given to the patients and families who have suffered from Legionnaires Disease during what has been a very difficult time.’

The test results back now show that the public risk following the outbreak has been effectively dealt with, which is good news for the public.

Dr Edwards said she endorsed earlier comments from the Medical Officer of Health Dr Alistair Humphrey that there are lessons to be learned from the outbreak. She hoped that the industry sector would now take the initiative and look at improving protocols and regulations to assist businesses to develop a more structured system for managing the potential risk from cooling towers.

Ends.

Please note there is no further comment from the CDHB at this time.

Vivienne Allan
Communications Manager

The Canterbury District Health Board (CDHB) Legal Notice

News

Canterbury District Health Board Media releases: CDHB Releases Water Cooling Tower Results 2 September 2005
Clear Lessons to be Learnt from Outbreak of Legionella in Christchurch 1 September 2005
Update on Legionnaires' Disease 26 August 2005; Update on Legionnaires' Disease 23 August 2005
Public Health Teams Start Study on Legionnaires Disease in City 19 August 2005; Update on Legionnaires Disease 12 August 2005

New Zealand Herald: City battles to find source of legionnaires' disease, article by Jarrod Booker, 18 August 2005

The Press: Fertiliser plant had strain of legionella, article by Kim Thomas, 3 September 2005
Expose legionella towers - expert, article by Kamala Hayman and Louise Bleakley, 1 September 2005; Legionella found in towers, article by Kamala Hayman, 24 August 2005; Disease found in 19th victim, article by Yvonne Martin, 13 August 2005; Disease remains a puzzle, article by Joanna Davis, 12 August 2005
Council joins search for legionnaires' source, article by Joanna Davis and Louise Bleakley, 11 August 2005

Television New Zealand: Source of outbreak proving elusive, 9 August 2005