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| {{Infobox disease | |||
| | Name = Legionellosis | |||
| | Image = | |||
| | Caption = | |||
| | DiseasesDB = 7366 | |||
| | ICD10 = {{ICD10|A|48|1|a|30}}, {{ICD10|A|48|2|a|30}} | |||
| | ICD9 = {{ICD9|482.84}} | |||
| | ICDO = | |||
| | OMIM = | |||
| | MedlinePlus = 000616 | |||
| | eMedicineSubj = med | |||
| | eMedicineTopic = 1273 | |||
| | MeshID = D007876 | |||
| }} | |||
| '''Legionellosis''' is the medical term for the potentially fatal, acute infectious respiratory process caused by any species of the ], aerobic ] belonging to the genus '']''.<ref name=Sherris>{{cite book | author = Ryan KJ, Ray CG (editors) | title = Sherris Medical Microbiology | edition = 4th | publisher = McGraw Hill | year = 2004 | isbn = 0-8385-8529-9 }}</ref> Over 90% of legionellosis cases are caused by '']'', the bacterium responsible for ''']''', also known as '''Legion Fever'''. | |||
| However, other species include '']'', ''Legionella feeleii'', ''Legionella micdadei'' and ''Legionella anisa''. These species cause a lesser, non-fatal, acute infectious process known as ''']''' that resembles acute influenza. These species can be water-borne or present in soil, whereas ''L. pneumophila'' has only been found in aquatic systems, where it is symbiotically present in aquatic-borne ].<ref>{{cite pmid|10528878}}</ref> It thrives in temperatures between 25 and 45 °C (77 and 113 °F), with an optimum temperature of 35 °C (95 °F). | |||
| During infection, the bacterium invades macrophages and lung epithelial cells and replicates intracellularly.<ref>{{cite pmid|20051107}}</ref><ref name="autogenerated1">{{cite book |author=Swanson M, Heuner K |title=Legionella: Molecular Microbiology |publisher=Caister Academic Pr |year=2008 |isbn=1-904455-26-3}}</ref> | |||
| It is not transmitted from person to person. Instead, it is transmitted by inhalation of ] water and/or soil contaminated with the bacteria. Sources where temperatures allow the bacteria to thrive include hot-water tanks, cooling towers and evaporative condensers of large air-conditioning systems, such as those commonly found in hotels and large office buildings. Though the first known ] was in ], ], cases of legionellosis have occurred throughout the world.<ref>{{cite web|url=http://www.who.int/water_sanitation_health/emerging/legionella_rel/en/index.html |title=WHO | Legionella and the prevention of legionellosis |publisher=Who.int |date=2012-02-21 |accessdate=2013-03-23}}</ref> | |||
| ==First known cases== | |||
| {{See also|1976 Philadelphia legionellosis outbreak|List of Legionellosis outbreaks}} | |||
| Legionnaires' disease acquired its name in July 1976, when an ] of ] occurred among people attending a convention of the ] at the ] in ]. Of the 182 reported cases, mostly men, 29 died.<ref>{{cite web|title=Legionnaire disease|url=http://www.britannica.com/EBchecked/topic/335050/Legionnaire-disease|publisher=Encyclopaedia Britannica|accessdate=30 October 2013}}</ref> On January 18, 1977, the causative agent was identified as a previously unknown strain of ], subsequently named '']'', and the species that caused the outbreak was named '']''.<ref>McDade, J.E., Brenner, D.J., Boeman, F.M.. (1979). Legionnaires' disease bacterium isolated in 1947. Ann Intern Med. 90: 659-661.</ref><ref>Fraser, D.W., Tsai, T,. Orenstein, W., et al. (1977). Legionnaires' disease: description of an epidemic of pneumonia. New England Journal of Medicine. 297: 1186-1196.</ref> | |||
| Some people can be infected with the ''Legionella'' bacteria and have only mild symptoms or no illness at all. This form of Legionnaires' disease is known as ].<ref>http://jid.oxfordjournals.org/content/191/9/1530.full.pdf</ref> | |||
| Outbreaks of Legionnaires' disease receive significant media attention. However, this disease usually occurs as single, isolated cases not associated with any recognized outbreak. When outbreaks do occur, they are usually in the summer and early autumn, though cases may occur at any time of year. Most infections occur in those who are middle-aged or older.<ref name="ReferenceA">{{MedlinePlusEncyclopedia|000616|Legionnaire's disease}}</ref> | |||
| ==Signs and symptoms== | |||
| Patients with Legionnaires' disease usually have fever, chills, and a cough, which may be dry or may produce ]. Some patients also have muscle aches, headache, tiredness, loss of appetite, loss of coordination (ataxia), and occasionally diarrhea and vomiting. Confusion and impaired cognition may also occur,<ref>Edelstein PH. Legionnaires Disease: History and clinical findings. Open Access Biology http://www.open-access-biology.com/legionella/edelstein.html</ref> as can a so-called 'relative ]', i.e. low or low normal heart rate despite the presence of a fever.<ref>{{cite journal |author=Ostergaard L, Huniche B, Andersen PL |title=Relative bradycardia in infectious diseases |journal=J. Infect. |volume=33 |issue=3 |pages=185–91 |year=1996 |month=November |pmid=8945708 |doi=10.1016/S0163-4453(96)92225-2}}</ref> Laboratory tests may show that patients' renal functions, liver functions and electrolytes are deranged, including ]. Chest X-rays often show pneumonia with bi-basal ]. It is difficult to distinguish Legionnaires' disease from other types of pneumonia by symptoms or ] findings alone; other tests are required for diagnosis. | |||
| Persons with Pontiac fever experience fever and muscle aches without 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. | |||
| ==Potential reservoirs== | |||
| Potential sources of contaminated water include ] (some 40% to 60% of ones tested<ref>{{cite web |url=http://cti.org/cgi-bin/download.pl |title=Legionellosis Guideline: Best Practices for Control of ''Legionella'' (WTP-148) (06) |publisher=Cooling Technology Institute |accessdate=2010-09-11}}</ref>) used in industrial cooling water systems as well as in large ] systems, ]s, ]s, ], ], ], ]s, ]s,<ref>{{cite web|url=http://www.physorg.com/news195847365.html |title=Legionnaires' disease link to lack of windscreen wash |publisher=Physorg.com |date=2010-06-15 |accessdate=2010-09-11}}</ref> ], ], ], ] equipment, and similar disseminators that draw upon a public water supply. | |||
| The disease may also be transmitted from contaminated aerosols generated in ] if the disinfection and maintenance program is not done rigorously.<ref>Silivanch v. Celebrity Cruises, Inc., 171 F.Supp.2d 241 (S.D.N.Y. 2001) (plaintiff successfully sued cruise line and manufacturer of filter after catching disease on cruise)</ref> Freshwater ponds, creeks, and ornamental fountains are potential sources of ''Legionella''.<ref name="Winn_b">{{cite book | author = Winn WC Jr | title = Baron's Medical Microbiology |chapter=Legionella |editor= Baron S ''et al''. eds | edition = 4th | publisher = Univ of Texas Medical Branch | year = 1996 | isbn = 0-9631172-1-1 |url= http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mmed.section.2235}} Via NCBI Bookshelf.</ref> The disease is particularly associated with hotels, fountains, ]s and hospitals with complex potable water systems and cooling systems. | |||
| Respiratory care devices such as humidifiers and nebulizers used with contaminated tap water may contain Legionella. Using sterile water is very important, especially when using respiratory care devices.<ref name=Woo92>{{cite journal |author=Woo AH, Goetz A, Yu VL |title=Transmission of Legionella by respiratory equipment and aerosol generating devices |journal=Chest |volume=102 |issue=5 |pages=1586–90 | |||
| |year=1992 |month=November |doi=10.1378/chest.102.5.1586 |pmid=1424896 |url=http://www.chestjournal.org/cgi/pmidlookup?view=long&pmid=1424896}}</ref> | |||
| Potting mix and compost is also another potential source, especially breathing airborne bacteria therefrom. | |||
| Other Legionella sources: | |||
| -Jetted bathtubs | |||
| -Indoor fountains | |||
| -Spas and hot tubs | |||
| -Shower heads <ref>http://www.mayoclinic.com/health/legionnaires-disease/DS00853/DSECTION=causes</ref> | |||
| ==Diagnosis== | |||
| ] | |||
| People of any age may suffer from Legionnaires' disease, but the illness most often affects middle-age and older persons, particularly those who smoke cigarettes or have ]. ] patients are also at elevated risk. Pontiac fever most commonly occurs in persons who are otherwise healthy. | |||
| The most useful diagnostic tests detect the bacteria in sputum, find ''Legionella'' antigens in urine samples (due to renal fibrosis), or the comparison of ''Legionella'' antibody levels in two blood samples taken 3 to 6 weeks apart. A urine antigen test which is simple, quick, and very reliable will only detect ''Legionella pneumophila'' serogroup 1, which accounts for 70% of disease cause by L. pneumophila. This test was developed by Richard Kohler and described in the Journal of Infectious disease in 1982 while Dr. Kohler was a junior faculty member at the Indiana University School of Medicine.<ref name="pmid7050258">{{cite journal |author=Kohler R, Wheat LJ |title=Rapid diagnosis of pneumonia due to Legionella pneumophila serogroup 1 |journal=J. Infect. Dis. |volume=146 |issue=3 |page=444 |year=1982 |month=September |doi=10.1093/infdis/146.3.444 |pmid=7050258 |url=http://www.jid.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=7050258}}</ref> In addition the urine antigen test will not identify the specific subtypes; so it cannot be used to match the patient with the environmental source of infection. Legionella can be isolated on a ] as well. | |||
| Legionella stains poorly with gram stain, stains positive with silver, and is cultured on charcoal yeast extract with iron and cysteine. | |||
| There is a significant under-reporting problem with Legionellosis. Even in countries with effective health services and readily available diagnostic testing, about 90% of cases of Legionnaires' disease are missed. This is partly due to Legionnaire's disease being a relatively rare form of pneumonia, which many clinicians will not have encountered before and therefore may mis-diagnose. A further issue is that patients with Legionellosis can present with a wide range of symptoms some of which (such as diarrhea) may distract clinicians from making a correct diagnosis.<ref>{{cite journal |author=Makin, Dr T |title=Legionella bacteria and solar pre-heating of water for domestic purposes |journal=UK Water Regulations Advisory Scheme Report|page=4 |para=12 |year=2008 |month=January |url=http://www.wras.co.uk/PDF_Files/Preheated_Water_Report.pdf}}</ref> | |||
| ==Treatment== | |||
| Current treatments of choice are the respiratory tract ] (], ], ]) or newer ] (], ], ]). The ]s used most frequently have been levofloxacin and azithromycin. Macrolides are used in all age groups while tetracyclines are prescribed for children above the age of 12 and quinolones above the age of 18. ] can be used in combination with a quinolone or macrolide. It is uncertain whether rifampicin is an effective antibiotic to take for treatment.The Infectious Diseases Society of America does not recommend the usage of rifampicin with added regimens. ] and ] led to improved outcomes compared to other antibiotics in the original American Legion outbreak. These antibiotics are effective because they have excellent intracellular penetration in ''Legionella'' infected cells. | |||
| The mortality at the original American Legion convention in 1976 was high (34 deaths in 180 infected individuals) because the antibiotics used (including ]s, ]s, and ]s) had poor intracellular penetration. Mortality has plunged to less than 5% if therapy is started quickly. Delay in giving the appropriate antibiotic leads to higher mortality. | |||
| ==Prognosis== | |||
| The fatality rate of Legionnaires' disease has ranged from 5% to 30% during various outbreaks and approaches 50% for ], especially when treatment with antibiotics is delayed.<ref name="ReferenceA"/> According to the journal '']'', hospital-acquired Legionella pneumonia has a fatality rate of 28%, and the principal source of infection in such cases is the drinking-water distribution system.<ref>{{cite journal |author=Stout JE, Muder RR, Mietzner S, ''et al.'' |title=Role of environmental surveillance in determining the risk of hospital-acquired legionellosis: a national surveillance study with clinical correlations |journal=Infect Control Hosp Epidemiol |volume=28 |issue=7 |pages=818–24 |year=2007 |month=July |pmid=17564984 |doi=10.1086/518754 |url=http://www.journals.uchicago.edu/doi/abs/10.1086/518754?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%3dpubmed}} </ref> | |||
| ==Epidemiology== | |||
| Much has been learned about the epidemiology of Legionnaires' disease since the ] was first identified in 1976. National surveillance systems and research studies were established early, and in recent years improved ascertainment and changes in clinical methods of diagnosis have contributed to an upsurge in reported cases in many countries. Environmental studies continue to identify novel sources of infection, leading to regular revisions of guidelines and regulations. There are about 8,000 to 18,000 cases of Legionnaires' disease each year in the United States, according to the Bureau of Communicable Disease Control.<ref>{{cite web |url= http://www.mass.gov/eohhs/gov/departments/dph/http://cmr.asm.org/content/15/3/506 |title=Legionellosis. |date=Nov 2011 |work=Massachusetts Department of Public Health. Bureau of Communicable Disease Control.|accessdate=2012-11-12}}</ref> | |||
| Between 1995 and 2005 over 32,000 cases of Legionnaires' disease and more than 600 outbreaks were reported to the ] (EWGLI). In the future, there may be an increase in cases as the population becomes more elderly. There is a shortage of data on ''Legionella'' in developing countries and it is likely that ''Legionella''-related illness is underdiagnosed worldwide.<ref>World Health Organization 2007. ''Legionella'' and the prevention of legionellosis. Geneva, Switzerland: WHO. Available at http://www.who.int/water_sanitation_health/emerging/legionella.pdf</ref> Improvements in diagnosis and surveillance in developing countries would be expected to reveal far higher levels of morbidity and mortality than are currently recognised. Similarly, improved diagnosis of human illness related to ''legionella'' species and serogroups other than ''Legionella pneumophila'' would improve knowledge about their incidence and spread. | |||
| ==See also== | |||
| *] | |||
| *] | |||
| *] | |||
| ==References== | |||
| {{reflist|2}} | |||
| ==External links== | |||
| * {{DMOZ|Health/Conditions_and_Diseases/Infectious_Diseases/Bacterial/Legionellosis/}} | |||
| * | |||
| * | |||
| {{Bacterial diseases}} | |||
| {{Respiratory pathology}} | |||
| ] | |||
| ] | |||
| ] | |||
| ] | |||
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