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Combating a rising incidence of Legionnaire's disease

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VOL: 102, ISSUE: 39, PAGE NO: 25

Jason Beckford-Ball, BA, RMN, is assistant clinical editor, Nursing Times

A statement released last week by the Health Protection Agency highlighted a recent increase in the incidence of Le...

A statement released last week by the Health Protection Agency highlighted a recent increase in the incidence of Legionnaire's disease in England and Wales. Although an upsurge in cases is common at this time of year due to people returning from holidays abroad, only a small proportion of the recent cases can be attributed to foreign travel. Nurses need to be aware of the symptoms and what health measures they can take.

A statement released last week by the Health Protection Agency (HPA, 2006) highlighted a recent increase in the incidence of Legionnaire's disease in England and Wales. Since the beginning of August 2006, 127 cases have been reported with onset of illness, including cases acquired in the UK and abroad, compared with a total of only 63 cases in August 2005.

The total number of cases this year is also set to exceed that of 2005 as late reports are received. So far 273 cases have been reported, compared with 205 up to the end of August 2005 (HPA, 2006).

An upsurge in cases is common at this time of year due to people returning from foreign travel, but only a small proportion of the recent cases can be attributed to people contracting Legionnaire's while on holiday.

The HPA statement shows that the recent upsurge comprises small clusters around England and Wales and although there is no evidence linking them, local health protection units are monitoring the trend to see if a pattern emerges. If Legionnaire's disease is found to be on the increase, it is important nurses are aware of the symptoms and what health measures they can take.

What is it?

Legionnaire's disease is an acute bacterial pneumonia that results from infection with Legionella pneumophila and leads to fever-like symptoms (Anderson et al, 2002). It is usually self-limiting, although mortality rates have been as high as 15-20% in a few localised outbreaks.

Legionella pneumophila thrive in warm water (between 20 degsC and 60 degsC) and the disease is usually spread through man-made water systems, such as air-conditioning and cooling systems, spas, the water reservoirs of humidifiers and nebulisers, which provide perfect conditions for the bacteria to congregate. Infection occurs when people inhale water droplets from these sources.

Legionnaire's disease has a higher mortality rate in older people (Anderson et al, 2002), especially if they have any pre-existing respiratory disorder. People who smoke as well as those who have a lowered immune system are also at a greater risk.

Legionella pneumophila can also cause Pontiac fever, which is a less serious flu-like illness that persists for a few days.

There is no record of any person-to-person contamination and it cannot be contracted by drinking water contaminated by Legionella pneumophila.

Symptoms

Symptoms usually start between two and 10 days after the person has been infected (Lawrence and May, 2003). They include:

- Fever;

- Sweating;

- Severe headache;

- Shortness of breath;

- Chest pains may result if the infection affects the pleura;

- A cough, which increases in severity;

- Blood-stained sputum.

In more severe cases, the infection can spread to other parts of the body, resulting in diarrhoea, vomiting, confusion and kidney and liver damage. The organs most affected are the lungs, however, and this is usually the cause of death.

Diagnosis

A diagnosis can be arrived at by a microbiology check of antibodies to the Legionella bacteria in the blood. A recent infection will show a rapid rise in antibody levels in a short period. There may be a fourfold rise in a few days.

A microbiology diagnosis can also be confirmed by isolating Legionella pneumophila in a sputum sample. A urine sample can also be tested to confirm that the bacteria are Legionella pneumophila.

Treatment

The primary treatments are antibiotics and supportive therapy (Anderson et al, 2002). Antibiotic treatment should be started as soon as Legionnaire's is suspected, without waiting for confirmation by microbiology. Most patients' symptoms will improve within 48 hours of commencing antibiotic therapy, which is usually erythromycin (Anderson et al, 2002), sometimes with a second antibiotic, rifampicin. Tetracycline, alone or with rifampicin, can also be used.

Current guidelines

The guidelines for reporting cases vary. In England and Wales Legionnaire's disease is not a notifiable condition so there is no legal requirement for nurses to report an outbreak to the HPA (Health and Safety Executive/Local Authorities Enforcement Liaison Committee, 2002). In Scotland, however, any case has to be formally reported.

The HSE does stress, however, that there is an informal UK-wide notification system. This involves the microbiological laboratory confirming the diagnosis and notifying the trust's consultant in communicable disease control (CCDC) who informs the HPA's communicable disease surveillance centre, allowing outbreaks to be monitored.

Nurses should therefore be able to identify a patient who may be infected and know the correct steps to take. The HPA has provided guidelines for investigating single cases of Legionnaire's disease (HPA, 2002).

Confirm the diagnosis

A definitive diagnosis of Legionnaire's disease cannot be made by symptomatology alone (HPA, 2002). Nurses need to ensure that if a patient is displaying any symptoms (see above) then these are supported by microbiological evidence.

Inform the local CCDC

This is especially important for nurses working in primary care who will have to send a patient's samples offsite. It is vital that as soon as a diagnosis of Legionnaire's disease is confirmed the local CCDC is informed quickly in order that follow-up procedures can be initiated (HPA, 2002).

Obtain two-week history

The incubation period ranges from 2-10 days but symptoms can take up to a fortnight to develop. Also, the precise date of onset may not be known. The CCDC's agent should collect details of the patient's movements for two weeks before the illness onset so that the source of the infection can be identified (HPA, 2002). This includes:

- Place of residence;

- Place of work;

- Any travel;

- Exposure to showers in leisure centres;

- Exposure to showers and respiratory systems in hospital or domestic settings.

Cases with an incomplete history should still be reported as early detection can be crucial to managing an outbreak (HPA, 2002).

Nursing considerations

The temperature of hot water in public buildings such as hospitals is often over 60 degsC to combat the spread of Legionnaire's disease. Nurses should take precautions to ensure that staff and patients are informed of high water temperatures in order to avoid scalds, including warning signs at sinks. Nurses in secondary care can also take responsibility for their wider environment, for example by ensuring that air-conditioning units are well-maintained (Little, 2003).

Vulnerable groups

Outbreaks of Legionnaire's disease have the greatest impact on vulnerable groups such as older people. Nurses working in services for these groups, such as nursing homes, should be especially vigilant.Key points

- There has been a recent rise in the cases of Legionnaire's disease in England and Wales that are not attributable to people returning from foreign holidays.

- Legionnaire's disease is an acute bacterial pneumonia that is caused by infection with Legionella pneumophila and results in fever-like symptoms.

- The primary treatments are antibiotics and supportive therapy.

- It is important that nurses are able to identify a patient who may be infected so that an outbreak can be monitored.

- Outbreaks of Legionnaire's disease have the most impact on vulnerable groups such as older people.

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