| Legionellosis | ||
|---|---|---|
| ICD-10 code: | A48.1 | |
| ICD-9 code: | 482.8 | |
Legionellosis is an infection caused by species of the bacterium Legionella, most notably L. pneumophila. At least 46 Species and 70 serogroups have been identified. L. pneumophila, a ubiquitous aquatic organism that thrives in warm environments (25°- 45°C with an optimum around 35°C) causes over 90% of Legionnaires Disease.
The disease has two distinct forms:
Legionnaires' disease acquired its name in 1976 when an Outbreak of Pneumonia occurred among persons attending a convention of the American Legion in Philadelphia. Later, the bacterium causing the illness was named Legionella.
On January 18, 1977 scientists identified a previously unknown bacterium as the cause of the mysterious "Legionnaires' disease."
An estimated 8,000 to 18,000 people get Legionnaires' disease in the United States each year. Some people can be infected with the Legionella bacterium and have mild symptoms or no illness at all.
Outbreaks of Legionnaires' disease receive significant media attention. However, this disease usually occurs as a single, isolated case not associated with any recognized outbreak. When outbreaks do occur, they are usually recognized in the summer and early fall, but cases may occur year-round. About 5% to 30% of people who have Legionnaires' disease die.
Persons with Pontiac fever experience fever and muscle aches and do not have pneumonia. They generally recover in 2 to 5 days without treatment.
The time between the patient's exposure to the bacterium and the onset of illness for Legionnaires' disease is 2 to 10 days; for Pontiac fever, it is shorter, generally a few hours to 2 days.
Extraintestinal Infections: L. pneumophila is specifically considered as a pathogen of the respiratory tract, where it is a cause of atypical pneumonia, also known as Legionnaires' disease. Other infections have also been reported, including haemodialysis fistulae, Pericarditis and wound and skin infections. Bacteraemia is often associated with Legionnaires' disease.
One species Legionella longbeachae is contracted via inhaling infected compost or soil
Animal Infections: None specifically recorded. Infections of Protozoa: Protozoa such as Harmanella vermiformis and related protozoa have been shown to be able to support the growth of L. pneumophila in tap water. Also Acanthamoeba, Naegleria and Tetrahymena can be infected by L. pneumophila. It is considered that this may be how these fastidious organisms survive in the environment.
Several types of tests are available. The most useful tests detect the bacteria in sputum, find Legionella antigens in urine samples, or compare antibody levels to Legionella in two blood samples obtained 3 to 6 weeks apart.
Pontiac fever most commonly occurs in persons who are otherwise healthy.
Pontiac fever requires no specific antibiotic treatment.
Legionella longbeachae, one species in the Legionella family, is found in soils, and compost. Persons inhaling soil or compost dust containing Legionella longbeachae risk contracting Legionnaires' Disease. Thus, an additional risk source can be pre-purchased bags of soil, compost, or potting mix.
During outbreaks, CDC and health department investigators seek to identify the source of disease transmission and recommend appropriate prevention and control measures, such as decontamination of the water source. Current research will likely identify additional prevention strategies.
In September 2004, it was revealed in an article in the magazine 'Science' that the complete Genome of Legionella pneumophila has been unraveled. This will help researchers to find out how exactly the bacterium works and how people can be protected against Infection.
The world's largest Outbreak of legionnaries' disease happened in July 2001 (the patients began to go to the hospital on July 7), in Murcia, Spain, where more than 800 suspected cases were recorded by July 22, when the last case was treated; 636–696 of these cases were estimated and 449 confirmed (so, at least 16,000 persons were exposed to the bacterium) and 6 dead (this is, a case-fatality rate of approximately 1%.).
A controlled case study matching 85 patients living outside the city of Murcia with two controls each was undertaken to identify the outbreak source; the epidemiologic investigation implicated the cooling towers at a city hospital (Morales Meseguer Hospital). An environmental isolate from these towers with an identical molecular Pattern as the clinical isolates was subsequently identified and supported that epidemiologic conclusion.
In 2002 Barrow suffered the UK's worst outbreak of legionnaires' disease. Six women and one man died as a result of the illness, another 172 people also contracted the disease. The caused was found to be faulty air conditioning at the town's Forum 28 arts centre.
The first known case of the disease discovered in Norway happened in 2001. 28 people were infected in the city of Stavanger, and seven people died. At first the authorities were puzzled as several of the victims lived all around the country, including one in Germany and another in England. After a massive hunt the source of the outbreak turned out to be the small lake of Breiavatnet, which has a fountain in the middle of it. The fountain had sprayed the bacteria into the air, in turn getting picked up by a cooling system at a Stavanger hotel close by. Only three of the infected had stayed at the hotel but it turned out the exit shaft of the cooling tower was right next to a public bus stop, explaining the other victims.
In May 2005 there was a second-greater-outbreak in Norway, this time originating in the southeastern town of Fredrikstad. As of 8 June 2005, 52 patients were confirmed infected and ten people were dead. The dead were all from Fredrikstad or nearby cities, in age ranging from 68 to early 90's. The source of the outbreak unexpectedly came from an air scrubber (an industrial air Purification facility; this particular one operated by Borregaard Industries in Sarpsborg). Such an installation has never before been reported as a source of Legionellosis anywhere in the world. Although the source was finally identified by DNA matching, it was also fairly well identified by analysing risk increases from people living near suspected sources.
In October 2005 at least 21 people have died and over 100 fallen ill during an outbreak at the Seven Oaks Home for the Aged in Toronto, Ontario, Canada. Legionnaire's disease was originally ruled out as being the cause, but post-mortem examinations confirmed that victims had Legionella bacteria in their lungs. The outbreak is still being investigated, and researchers believe this particular outbreak may be related to a new strain of the bacteria. . Since October 4, two additional cases of the disease have been reported by residents of the area who had never visited Seven Oaks. This has investigators puzzled, and they believe that a faulty cooling tower at Seven Oaks may have not only caused residents of the home to fall ill, but also people walking nearby outside.