Legionnaires disease is a form of atypical pneumonia caused by the type of bacteria Legionella . Signs and symptoms include cough, shortness of breath, high fever, muscle aches, and headaches. Nausea, vomiting, and diarrhea may also occur. It often begins two to ten days after exposure.
These bacteria are found naturally in freshwater. Can contaminate hot water tanks, hot tubs, and large air conditioning cooling towers. Usually spread by inhaling the fog containing bacteria. This can also happen when contaminated water is aspirated. It usually does not spread directly between people and most people who are not infected. Risk factors for infection include older age, smoking history, chronic lung disease, and poor immune function. It is recommended that those with severe pneumonia and those with pneumonia and recent travel history be tested for this disease. Diagnosis is done by urine antigen test and sputum culture.
There is no vaccine. Prevention depends on maintaining a good water system. Legionnaires disease treatment is with antibiotics. Recommended agents include fluoroquinolones, azithromycin, or doxycycline. Hospitalization is often necessary. About 10% of those infected died.
The number of cases happening globally is unknown. It is estimated that Legionnaires disease is the cause between two and nine percent of cases of pneumonia acquired outside the hospital. An estimated 8,000 to 18,000 cases per year in the United States require inpatient care. Outbreaks of disease are responsible for a small proportion of cases. Although it can happen anytime the year is more common in summer and autumn. The disease was named after the outbreak where it was first identified - the 1976 American Legion convention in Philadelphia.
Video Legionnaires' disease
Signs and symptoms
The length of time between exposure to bacteria and the appearance of symptoms is generally two to ten days, but rarely can extend up to 20 days. For the general population, among them exposed between 0.1% and 5% developed the disease, while among those in the hospital between 0.4% and 14% developed the disease.
Those who have Legionnaires disease usually have fever, chills, and cough, which may be dry or may produce phlegm. Almost all with Legionnaires fever experience, while about half cough with phlegm, and a third of coughing blood or bloody sputum. Some also experience muscle aches, headaches, fatigue, loss of appetite, loss of coordination (ataxia), chest pain, or diarrhea and vomiting. Up to half of those with Legionnaires disease have gastrointestinal symptoms, and nearly half have neurological symptoms, including confusion and cognitive impairment. "Relative bradycardia" may also be present, ie low or normal low heart rate despite fever.
Laboratory tests may indicate that renal function, liver function and electrolyte levels are not normal, which may include low sodium in the blood. Chest X-rays often show pneumonia with consolidation in the lower part of both lungs. It is difficult to distinguish Legionnair's disease from other types of pneumonia with radiological symptoms or findings alone; other tests are needed for a definitive diagnosis.
People with Pontiac fever have fever and muscle pain without pneumonia. They generally heal within two to five days without treatment. The fever of Pontiac time between exposure and symptoms is generally several hours to two days.
Maps Legionnaires' disease
Cause
More than 90% of cases of Legionnaires disease are caused by the bacteria Legionella pneumophila. Other types include L. longbeachae , L. feeleii , L. micdadei , and L. anisa .
Transmission
Legionnaires disease is usually spread by respiration in aerosolized water and/or soil contaminated with the bacteria Legionella . Experts have stated that Legionnaires disease is not transmitted from person to person. In 2014 there is one possible case of spread from a sick person to a caregiver. Rarely, it has been transmitted by direct contact between contaminated water and surgical wounds. Bacteria grow best at warm temperatures. It grows at water temperatures between 25 and 45 Â ° C (77 and 113 Â ° F), with an optimum temperature of 35 Â ° C (95 Â ° F). Temperatures above 60 Â ° C (140 Â ° F) kill it. Sources in which temperatures allow bacteria to thrive include hot water tanks, cooling towers, and condenser evaporators of large air conditioning systems, such as those commonly found in hotels and large office buildings. Although the first known outbreak was in Philadelphia, Pennsylvania, cases of legionellosis have occurred worldwide.
Reservoir
L. pneumophila thrives in aquatic systems where it is established in amoebae in a symbiotic relationship. Legionella bacteria survive in water as intracellular parasites of live water protozoa, such as amoeba. Amoeba are often part of biofilms, and once Legionella and infected amoeba are protected in biofilms, they are very difficult to destroy.
In built environments, central air-conditioning systems in office buildings, hotels, and hospitals are contaminated water sources. Other places that can be occupied include cooling towers used in industrial cooling systems, evaporative coolers, nebulizers, humidifiers, whirlpools, hot water systems, showers, windshield washers, fountains, air humidifiers, ice-making machines and drizzle systems which are usually found in grocery stores produce sections.
The disease may also be transmitted from contaminated aerosols generated in hot tubs if disinfection and maintenance programs are not followed strictly. Freshwater ponds, tributaries, and ornamental fountains are potential sources of Legionella . The disease is mainly associated with hotels, fountains, cruises, and hospitals with complex drinking water systems and cooling systems. Respiratory treatments such as moisturizers and nebulizers used with contaminated tap water may contain Legionella species, so using sterile water is essential.
Other sources include mixtures of pots and compost.
Mechanism
Legionella enters the lungs either with aspiration of contaminated water or inhaling aerosol contaminated water or soil. In the lungs, bacteria are consumed by macrophages, a type of white blood cell, in which Legionella bacteria multiply causing the death of macrophages. After the macrophages die, the bacteria are released from the dead cells to infect other macrophages. The virulent strain Legionella kills macrophages by blocking the fusion of phagosoma with lysosomes inside the host cell; usually bacteria contained in the phagosome, which is integrated with lysosomes, enabling enzymes and other chemicals to break down the invading bacteria.
Diagnosis
People of all ages may suffer from Legionnaires disease, but the disease most commonly affects middle-aged and elderly people, especially those who smoke or suffer from chronic lung disease. People with immunity are also at higher risk. Pontiac fever is most common in healthy people.
The most useful diagnostic tests detect bacteria in the coughed mucus, find Legionella antigen in the urine sample, or allow a comparison of Legionella levels of antibody in two blood samples taken 3 to 6 weeks. besides. The urine antigen test is simple, fast, and highly reliable, but will only detect Legionella pneumophila serogrup 1, which accounts for 70 percent of the disease caused by L. pneumophila , which means the use urine antigen test alone can lose as much as 30% of cases. This test was developed by Richard Kohler in 1982. When dealing with Legionella pneumophila serogroup 1, the urinary antigen test is useful for early detection of Legionnaire disease and treatment initiation, and has assisted in early detection of outbreaks. However, it will not identify certain subtypes, so it can not be used to match people with a source of environmental infection. Bacteria Legionella can be cultured from sputum or other respiratory samples. Legionella bad stains with Gram staining, positive stains with silver, and bred on charcoal yeast extract with iron and cysteine ​​(CYE agar).
Significant underlying reporting issues occur in legionellosis. Even in countries with effective health care and diagnostic tests available, about 90 percent of cases of Legionnaires disease are missed. This is partly due to Legionnaires disease which is a relatively rare form of pneumonia, which many doctors may have never faced before and thus can be misdiagnosed. A further problem is that people with legionellosis may present with a variety of symptoms, some of which (such as diarrhea) may distract doctors from making the correct diagnosis.
Prevention
Although the risk of Legionnaires disease spread by large-scale water systems can not be eliminated, it can be greatly reduced by writing and enforcing a very detailed and systematic water safety plan that is appropriate for the particular types of facilities involved (office buildings, hospitals, hotels, spas, ships cruises, etc. Some of the possible elements including the plan are as follows:
- Keep water temperatures above or below the 20-50 ° C (68-122 ° F) range where bacteria Legionella thrive.
- Prevent stagnation, for example by removing from pipelines any part that does not have an outlet (dead end). If stagnation is unavoidable, for example when the wing of the hotel is closed for the quiet season, the system must be completely disinfected just before resuming normal operation.
- Prevent the buildup of biofilms, for example by not using (or by replacing) construction materials that encourage its development, and by reducing the quantity of nutrients for bacterial growth into the system.
- Disinfect the system periodically, with high heat or chemical biocide, and use of chlorination if necessary. There is evidence that water treatment with copper-silver ionization or ultraviolet light may also be effective.
- System design (or renovation) that reduces aerosol production and reduces human exposure to them, for example by directing them away from building airways.
An effective water safety plan will also cover such things as training, recording, communication among staff, contingency plans and management responsibilities. The format and content of the plan may be determined by public health laws or regulations.
Treatment
Effective antibiotics include most macrolides, tetracyclines, ketolides, and quinolones. Legionella multiplies in cells, so effective treatment should have excellent intracellular penetration. The current preferred treatment is quinolone of the respiratory tract (levofloxacin, moxifloxacin, gemifloxacin) or newer macrolides (azithromycin, clarithromycin, roxithromycin). The most commonly used antibiotics are levofloxacin, doxycycline, and azithromycin.
Macrolides (azithromycin) are used in all age groups, while tetracycline (doxycycline) is prescribed for children over the age of 12 and quinolones (levofloxacin) over the age of 18 years. Rifampicin can be used in combination with quinolones or macrolides. It is uncertain whether rifampicin is an effective antibiotic to drink. The Infectious Diseases Society of America does not recommend the use of rifampicin with additional regimens. Tetracycline and erythromycin cause increased yield compared to other antibiotics in the original American Legion outbreak. These antibiotics are effective because they have excellent intracellular penetration in the infected cells Legionella . The recommended treatment is 5-10 days of levofloxacin or 3-5 days of azithromycin, but in immunocompromised people, having severe disease, or pre-existing health conditions, longer antibiotic use may be necessary. During outbreaks, prophylactic antibiotics have been successfully used to prevent Legionnaires disease in high-risk individuals who may have been exposed.
The death rate at the 1976 American Legion convention was high (29 deaths in 182 infected individuals) because the antibiotics used (including penicillin, cephalosporins, and aminoglycosides) had poor intracellular penetration. Death has dropped to less than 5% if therapy starts quickly. Delaying appropriate antibiotics leads to higher deaths.
Prognosis
Legionnaires disease death rates range from 5% to 30% during various outbreaks and close to 50% for nosocomial infections, especially when treatment with antibiotics is delayed. Legionella pneumonia found in the hospital has a death rate of 28%, and the main source of infection in such cases is the drinking water distribution system.
Epidemiology
Legionnaires disease got its name in July 1976, when an outbreak of pneumonia occurred among people attending the American Legion convention at the Bellevue-Stratford Hotel in Philadelphia. Of the 182 reported cases, most men, 29 died. On January 18, 1977, the causative agent was identified as an unknown bacterial strain, then named Legionella, and a species that caused the outbreak called Legionella pneumophila.
Legionnaires disease outbreak received significant media attention. However, the disease usually occurs in single and isolated cases unrelated to known outbreaks. When an outbreak occurs, they are usually in the summer and early fall, although cases can occur at any time of the year. Most infections occur in those who are middle-aged or older. The national supervisory system and research study were established earlier, and in recent years the increase in assurance and changes in clinical diagnostic methods has contributed to the increase in reported cases in many countries. Environmental studies continue to identify new sources of infection, leading to regular revision of guidelines and regulations. Approximately 8,000 to 18,000 cases of Legionnaires disease occur annually in the United States, according to the Bureau of Communicable Disease Control.
Between 1995 and 2005, over 32,000 cases of Legionnaires disease and more than 600 outbreaks were reported to the European Working Group on Legionella Infection Data at Legionella limited in developing countries and Legionella. related to me may not be diagnosed worldwide. Improvements in diagnosis and surveillance in developing countries are expected to show much higher levels of morbidity and mortality than currently recognized. Similarly, the increased diagnosis of human diseases associated with Legionella species and serogroups other than Legionella pneumophila will increase knowledge of the incidence and spread.
A 2011 study successfully used modeling to predict the probability of number of cases during Legionnair outbreaks based on date of symptom onset of outbreaks in the past. In this way, it is likely that the size of the outbreak can be predicted, allowing efficient and effective use of public health resources in managing outbreaks.
Outbreak
The first known case of Legionnaires disease occurred in 1976 in Philadelphia, Pennsylvania. Among the more than 2000 participants of the American Legion convention held at the Bellevue-Stratford Hotel, 182 participants developed the disease and 29 died.
In April 1985, 175 people in Stafford, England, were admitted to District Hospital or Kingsmead Stafford with chest infection or pneumonia. A total of 28 people died. Medical diagnosis indicates that Legionnaires disease is responsible and epidemiologic investigations directly trace the source of infection to an AC cooling tower on the roof of the Stafford District Hospital.
In March 1999, a major outbreak in the Netherlands occurred during Westfriese Flora flower show in Bovenkarspel; 318 people fell ill and at least 32 people died. This is the second deadly outbreak since the outbreak of 1976 and the most lethal possibility as some people are buried before Legionnaires disease has been diagnosed.
The largest epidemic of Legionnaires disease in the world occurred in July 2001 with people appearing in hospital on July 7 in Murcia, Spain. More than 800 suspected cases were recorded at the time the last case was treated on July 22; 636-696 of these cases were estimated and 449 confirmed (so, at least 16,000 people were exposed to the bacteria) and six died, the case fatality rate was about 1%.
At the end of September 2005, 127 residents of a nursing home in Canada fell ill with L. pneumophila . Within a week, 21 residents have died. Cultural outcomes are initially negative, which is unusual, such as L. pneumophila is a fussy bacteria, which means requiring certain nutrients and/or living conditions to grow. The source of the plague was traced to an air conditioning cooling tower on the roof of a nursing home.
On November 12, 2014, 302 people had been hospitalized after the Legionella outbreak in Portugal and 7 associated deaths had been reported. All cases, so far, have appeared in three civilian parishes from the municipality of Vila Franca de Xira on the northern outskirts of Lisbon, Portugal and are being treated in a hospital in the Greater Lisbon area. The source allegedly resides in the cooling tower of the fertilizer factory FertibÃÆ'Â © ria.
Twelve people were diagnosed with the disease in the Bronx, New York, in December 2014; the source was traced to a contaminated cooling tower on housing construction. In July and August 2015, another unrelated outbreak in the Bronx killed 12 people and left 120 people ill; the cases emerged from the cooling tower above a hotel. At the end of September, others died of illness and 13 fell ill in another unrelated outbreak in the Bronx. The cooling tower from which people are infected in the last outbreak has been cleaned up during the summer, raising concerns about how well bacteria can be controlled.
On August 28, 2015, a Legionnaire disease outbreak was detected at San Quentin State Prison in Northern California. 81 people are sick and the cause is the mud that has been built in the cooling tower.
Between June 2015 and January 2016, 87 cases of Legionnaires disease were reported by the Michigan Department of Health and Human Services for the city of Flint, Michigan and beyond. 10 of those cases are fatal.
In November 2017, an outbreak was detected at Hospital de SÃÆ'Â £ Francisco Xavier, Lisbon, Portugal, with up to 53 people diagnosed with the disease and five of them dying of it.
In Quincy, Illinois at the Illinois Veterans' home disease outbreak in 2015 killed 12 people and inflicted more than 50 others. It is believed to be caused by the supply of infected water. Three cases have been identified in November 2017.
References
External links
- Legionnaires disease in Curlie (based on DMOZ)
Source of the article : Wikipedia
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