<unk>  acquired its name in July 1976, when an outbreak of pneumonia occurred among people attending a convention of the American Legion at the Bellevue-Stratford Hotel in Philadelphia. Of the 182 reported cases, mostly men, 29 died. On 18 January 1977, the causative agent was identified as a previously unknown strain of bacteria, subsequently named Legionella, and the species that caused the outbreak was named Legionella pneumophila. Outbreaks of<unk>  receive significant media attention, but this<unk>  usually occurs in 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. 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. About 8,000 to 18,000 cases of<unk>  occur each year in the United States, according to the Bureau of Communicable<unk>  Control. Between 1995 and 2005, over 32,000 cases of<unk>  and more than 600 outbreaks were reported to the European Working Group for Legionella Infections. The data on Legionella are limited in developing countries, and Legionella-related illnesses likely are underdiagnosed worldwide. 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. A 2011 study successfully used modeling to predict the likely number of cases during<unk> ' outbreaks based on symptom onset dates from past outbreaks. In this way, the eventual likely size of an outbreak can be predicted, enabling efficient and effective use of public-health resources in managing an outbreak. Outbreaks An outbreak is defined as two or more cases where the onset of illness is closely linked in time (weeks rather than months) and space, where a suspicion or evidence exists of a common source of infection, with or without microbiological support (i.e. common spatial location of cases from travel history). In April 1985, 175 people in Stafford, England, were admitted to the District or Kingsmead Stafford Hospitals with chest infection or pneumonia. A total of 28 people died. Medical diagnosis showed that<unk>  was responsible and the immediate epidemiological investigation traced the source of the infection to the air-conditioning cooling tower on the roof of Stafford District Hospital. In March 1999, a large outbreak in the Netherlands occurred during the Westfriese Flora flower exhibition in Bovenkarspel; 318 people became ill and at least 32 people died. This was the second-deadliest outbreak since the 1976 outbreak and possibly the deadliest, as several people were buried before<unk>  had been diagnosed. The world's largest outbreak of<unk>  happened in July 2001, with people appearing at the hospital on 7 July, in Murcia, Spain. More than 800 suspected cases were recorded by the time the last case was treated on 22 July; 636–696 of these cases were estimated and 449 confirmed (so, at least 16,000 people were exposed to the bacterium) and six died, a case-fatality rate around 1%. In September 2005, 127 residents of a nursing home in Canada became ill with L. pneumophila. Within a week, 21 of the residents had died. Culture results at first were negative, which is not unusual, as L. pneumophila is a "fastidious" bacterium, meaning it requires specific nutrients, living conditions, or both to grow. The source of the outbreak was traced to the air-conditioning cooling towers on the nursing home's roof. In an outbreak in lower Quebec City, Canada, 180 people were affected with 13 resulting deaths due to contaminated water in a cooling tower. In November 2014, 302 people were hospitalized following an outbreak of legionellosis in Portugal, and seven related deaths were reported. All cases emerged in three civil parishes from the municipality of Vila Franca de Xira in the northern outskirts of Lisbon, and were treated in hospitals of the greater Lisbon area. The source is suspected to be located in the cooling towers of the fertilizer plant Fertibéria. Twelve people were diagnosed with the<unk>  in an outbreak in the Bronx, New York, in December 2014; the source was traced to contaminated cooling towers at a housing development. In July and August 2015, another, unrelated outbreak in the Bronx killed 12 people and made about 120 people sick; the cases arose from a cooling tower on top of a hotel. At the end of September, another person died of the<unk>  and 13 were sickened in yet another unrelated outbreak in the Bronx. The cooling towers from which the people were infected in the latter outbreak had been cleaned during the summer outbreak, raising concerns about how well the bacteria could be controlled. On 28 August 2015, an outbreak of<unk> s<unk>  was detected at San Quentin State Prison in Northern California; 81 people were sickened and the cause was sludge that had built up in cooling towers. Between June 2015, and January 2016, 87 cases of<unk>  were reported by the Michigan Department of Health and Human Services for the city of Flint, Michigan, and surrounding areas. The outbreak may have been linked to the Flint water crisis, in which the city's water source was changed to a cheaper and inadequately treated source. Ten of those cases were fatal. In November 2017, an outbreak was detected at Hospital de São Francisco Xavier, Lisbon, Portugal, with up to 53 people being diagnosed with the<unk>  and five of them dying from it. In Quincy, Illinois, at the Illinois Veterans Home, a 2015 outbreak of the<unk>  killed 12 people and sickened more than 50 others. It was believed to be caused by infected water supply. Three more cases were identified by November 2017. In the autumn of 2017, 22 cases were reported in a<unk>  outbreak at Disneyland in Anaheim, California. It was believed to have been caused by a cooling tower that releases mist for the comfort of visitors. The contaminated droplets likely spread to the people in and beyond the park. In July 2019, 11 former guests of the Sheraton Atlanta hotel were diagnosed with the<unk> , with 55 additional probable cases. In September 2019, 141 visitors to the Western North Carolina Mountain State Fair were diagnosed with<unk> , with four reported deaths, after a hot tub exhibit is suspected to have developed and spread the bacteria. At least one additional exposure apparently occurred during the Asheville Quilt Show that took place a few weeks after the fair in the same building where the hot tub exhibit was held. The building had been sanitized after the outbreak. In December 2019, the government of Western Australia's Department of Health was notified of four cases of<unk> . Those exposed had recently visited near Bali's Ramayana Resort and Spa in central Kuta.
Legionnaires' disease
Freshers' flu
Lemierre's syndrome
Boutonneuse fever
Scarlet fever
Bartonellosis
Listeriosis
Metal fume fever