There is an on-going outbreak of Legionnaires in South Wales. Currently 21 people have contacted Legionnaires as part of this outbreak and 2 have died.According to WHO
Legionellosis is a generic term describing the pneumonic and non-pneumonic forms of infection with Legionella. The non-pneumonic form is an acute, self-limiting influenza-like illness usually lasting 2-5 days. The incubation period is from a few and up to 48 hours. The main symptoms are fever, chills, headache, malaise and muscle pain (myalgia). No deaths are associated with this type of infection. Legionnaires’ disease has an incubation period of two to ten days (but up to 16 days has been recorded in some recent well-documented outbreaks). Initially, symptoms are fever, loss of appetite, headache, malaise and lethargy. Some patients may also have muscle pain, diarrhoea and confusion. There is also usually an initial mild cough, but as many as 50% of patients can present phlegm. Blood-streaked phlegm or hemoptysis occurs in about one-third of the patients. The severity of disease ranges from a mild cough to a rapidly fatal pneumonia. Death occurs through progressive pneumonia with respiratory failure and/or shock and multi-organ failure. Untreated Legionnaires’ disease usually worsens during the first week. In common with other risk factors causing severe pneumonia, the most frequent complications of legionellosis are respiratory failure, shock and acute kidney and multi-organ failure. Recovery always requires antibiotic treatment, and is usually complete, after several weeks or months. In rare occasions, severe progressive pneumonia or ineffective treatment for pneumonia can result brain in sequelae. The death rate as a result of legionnella is dependent on: the severity of the disease, the appropriateness of initial anti-microbial treatment, the setting where legionella was acquired, and host factors (i.e. the disease is usually more serious in patients with immuno-suppression). The case fatality rate may be as high as 40 - 80 per 100 in untreated immuno-suppressed patients and can be reduced to 5 - 30 per 100 through appropriate case management and depending on the severity of the clinical signs and symptoms. For persons able to develop an immune response the death rate is usually within the range of 10 - 15%.
At this point the source of the disease is unknown. According to a quote in the BBC:
Our investigations show that there is no single building visited by all the people linked to the outbreak. The sources, or source, are therefore likely to be industrial processes such as cooling towers.

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20 September 2010