A B C D E F G H I J K L M N O P R S T U V W

LEGIONNAIRES DISEASE

What is Legionnaires Disease ?

In July 1976 an outbreak of pneumonia occurred among members of the American Legion (ex-servicemen’s organisation) attending a convention in a Philadelphia hotel. It was months later that the causative agent was found and named Legionella pneumophila ( lung loving ). Since then many types of legionella have been found in the environment. The organism lives in the water of streams, lakes and mud. It can survive in a wide range of conditions: for example water with temperatures between 5 and 63 C. It is usually harmless to man but can cause disease when it finds its way to water supplies and air conditioning systems. Legionella infection shows itself in two different ways: Pontiac fever (named after the 1968 outbreak that occurred in Michigan) and Legionnaires' disease pneumonia (which is an infection of the lungs). Pontiac fever is a sudden, mild flu-like disease which lasts for a couple of days. It does not affect the lungs. On the other hand, the main feature of Legionnaires' disease is pneumonia. Two to ten days after being infected with the organism, the patient has a high fever, muscle pain, headache and cough without phlegm. You may also become vague and confused. You are usually sick enough to need admission to hospital. A chest x-ray may show the disease affecting the lungs. Laboratory tests on phlegm and blood samples may confirm the diagnosis.

How does Legionnaires Disease occur ?

The route of infection in the majority of patients seems to be the respiratory tract (air passages). Inhalation of fine drops of infected water probably leads to lung infection. It is not passed from person to person.

Why does Legionnaires Disease occur ?

Most cases of Legionnaires' disease occur between the ages of 40 and 70, predominantly in males, for reasons which are not understood. More than two thirds occur in urban areas, especially industrial estates. About one half of cases have been infected abroad. Cigarette smokers, patients with chronic (long-term) chest disease, alcoholics, the elderly and patients with immunosuppression (decreased body defence mechanisms due to certain diseases or drugs) are at increased risk.

Treatment Involved for Legionnaires Disease

The disease mainly affects the lungs and is treated with an antibiotic, erythromycin. If you are severely affected, you may need oxygen or mechanical ventilation to assist your breathing. This is more likely if you are elderly and there has been a delay in diagnosing the illness. The disease may also be more severe if you have any other condition which reduces your resistance at the time of infection. At present there is no vaccine to protect against the disease. Prevention is directed mainly at ensuring that the number of these germs in water supplies and air conditioning systems is kept very low. Complete eradication is difficult. Regular and proper maintenance of water distribution and air conditioning systems of large buildings, as recommended by the authorities, minimizes the risk of the disease.

During Treatment for Legionnaires Disease

The symptoms usually get better after 5 7 days. However, it is a serious illness and complications such as kidney failure or thromboctopenia (a disorder of blood clotting) may occur. Most patients recover from these problems with specialized treatment.

After Treatment for Legionnaires Disease

Once you get over the lung infection you should not suffer any long-term after-effects. It is not known whether the disease is likely to recur following a further contact with the legionella germ.

If Legionnaires Disease is Left Untreated

Some patients with only mild lung infection would recover completely. Others may become critically ill with breathing difficulties and kidney failure which could be fatal.

Effects on Family of Legionnaires Disease

It is possible that other people may have been infected at the same time without becoming ill. For example, they may have travelled abroad with you and stayed in the same hotel. They may work in the same place as you and have been exposed to the germs, without being affected. There is no evidence that you could infect other people with the germ which you yourself have caught.