1.1 本指南涵盖了对雇主、建筑物所有者和运营商、设施经理、健康和安全专业人员、公共卫生当局和其他人的适当回应:( 1. )对于水系统可能被称为军团菌的细菌污染的担忧（参见 6.1 ); 和( 2. )鉴定一个或多个退伍军人病或庞蒂亚克热病例（见 6.3 – 6.5 ). 关于限制水系统中军团菌繁殖、消毒人类接触军团菌的潜在来源以及预防医疗相关感染的全面明确建议超出了本指南的范围。 1.2 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.3 本标准并非旨在解决与其使用相关的所有安全问题（如有）。 本标准的用户有责任在使用前制定适当的安全和健康实践，并确定监管限制的适用性。 看见 7.3和 8.5 对于特定的危险声明。 ====意义和用途====== 5.1 可以检查水系统（参见第节 7. )并进行了测试（参见第节 8. )三种情况下的军团菌( 1. )在没有军团菌病报告的情况下（见 5.2 ); ( 2. )当报告单个军团菌病病例时（见 5.3 ); 和( 3. )在有限的时间段和地理区域内报告两个或两个以上军团菌病病例（见 5.4 ). 以下是考虑在没有疾病的情况下对供水系统进行军团菌检测时，建筑业主和运营商需要了解的因素（见 5.2 )对于单一军团菌病病例（见 5. 3. ). 另请参阅CDC 2003《预防保健相关肺炎指南》、CDC 2000《预防造血干细胞移植受者机会性感染指南》以及世界卫生组织《军团菌与军团菌病预防》。在供水系统中检测军团菌不足以确定该系统对健康的危害。然而，未能检测到军团菌并不表明该细菌不存在（见 6.2.4 )或者水系统可能不会对健康造成潜在危害。检测军团菌的方法在敏感性和特异性上有所不同（见 6.2 )实验室在分离和鉴定军团菌方面的技能和经验各不相同。从临床和环境样本中分离出明显相同的军团菌（见 6.2.1 , 6.6.2.4 ，和截面 8. )可能表明供水系统是导致患者感染的军团菌的来源（参见 5.3.2 ). 然而，由于不同的军团菌血清群或物种导致的退伍军人疾病病例不一定有不同的暴露来源，因为一个系统可能被一个以上的军团菌污染。及时检查、测试和治疗可能的军团菌源可能会减少设施所有者和经营者的法律责任。另请参阅APHA公共卫生法手册。 5.2 无疾病情况下军团菌的环境检测: 5.2.1 如果可能的话，相关雇主、建筑物所有者和运营商、设施经理和其他人寻求预防真实和潜在的健康危害。供水系统操作员可以通过定期监测军团菌来识别不良情况，并可以在细菌达到足以引起人类疾病的数量之前实施控制措施（见 6.2.4.2 ). CDC 2000《预防造血干细胞移植受者机会性感染指南》建议，由于与其他住院患者相比，移植受者罹患军团菌病和死亡的风险要高得多，在中心饮用水供应的水样中定期培养军团菌可被视为在移植中心和其他设施中预防军团菌病的整体战略的一部分，这些设施中居住着暴露在水中的高危感染者（见 6.4.2 ). 有证据表明，环境军团菌监测应被视为预防医院获得性退伍军人疾病的积极策略( 1. ). 然而，移植中心环境监测培养的最佳方法（即频率或站点数量）尚未确定，成本也较低- 对于移植中心或其他医疗机构，以及机构、商业或住宅建筑，尚未评估此类策略的有效性。 5.2.2 一些专家建议不要在没有疾病的情况下对供水系统进行军团菌检测，尤其是在医院或医疗设施以外的建筑物中，因为在供水系统中绝对排除这种细菌可能不是预防军团菌病的必要条件，也不可能在没有大量费用的情况下实现。微生物水监测增加了运营成本，并且可能难以解释测试结果（见 6.2.4 ). 环境样本中军团菌的鉴定也可能引起不必要的警报和不必要的补救。世界卫生组织出版物指出，军团菌检测不能被视为一项控制措施，但确实提供了一些证据，证明水安全计划有效，控制措施运作正常。 军团菌采样不能足够快地提供结果，以便用于操作监测，而应通过提供实时结果的措施，例如，监测杀菌剂浓度、温度和水的pH值。 5.3 单个（散发）军团菌病病例的军团菌环境检测: 5.3.1 在确认军团菌病后尽快检测潜在的军团菌源可能会增加识别责任源的可能性。环境条件和设备操作可能经常变化，这可能会影响军团菌检测的可能性。如果检查人员将采样推迟到确诊为军团菌病时，他们可能无法确定责任来源（见 6.6和 6.7 )或者直到搜索其他案例确定常见风险（参见第节） 9 ). 5.3.2 军团菌病患者在疾病潜伏期内经常接触一种以上的可能来源（见 6.4.3 , 6.5.3 )并且可能无法识别或回忆所有可能的暴露。从临床和环境样本中分离出明显相同的军团菌（见 6.2.1 , 6.6.2.4 ，和截面 8. )具有提示性，但由于军团菌种类、血清群和亚型的分布（见 6.1.1和 6.1.2 )在未知的环境中，也就是说，同一军团菌可以在多个水系中繁殖。如果没有临床分离物可与环境分离物进行比较，则可能很难确定导致军团菌传播的环境源（见 6.2.1 , 6.6.2.4 ). 在流行调查和疫情调查中测试的大部分供水系统中发现了军团菌。 在没有临床隔离的情况下，必须根据环境和流行病学信息确定军团菌的可能传播源（见第节） 7 – 9 ). 5.4 多发性军团菌病病例的军团菌环境检测- 在限定区域和有限时间内或共享潜在来源的多个军团菌病病例的识别( 1. )对可疑来源进行环境检查，以确定导致军团菌传播的水系统，以防止进一步的疾病（见第节） 7 – 9 ); 和( 2. )流行病学调查，以确定病例的常见风险因素（见 6.4.2 , 6.5.2 ). 流行病学调查的信息（见第节 9 )通常有助于确定军团菌病患者共享的特定环境，以及检查人员应关注的环境（见第节） 7和 8. ). 环境测试是对已识别问题的检查和及时纠正的补充，但不是替代（见第节） 10 )在所有可能的军团菌来源中，无论是否检测到军团菌或潜在来源是否与患者接触有关。

1.1 This guide covers appropriate responses for employers, building owners and operators, facility managers, health and safety professionals, public health authorities, and others: ( 1 ) to a concern that a water system may be contaminated with the bacterium known as legionella (see 6.1 ); and ( 2 ) to the identification of one or more cases of Legionnaires' disease or Pontiac fever (see 6.3 – 6.5 ). Comprehensive and explicit recommendations to limit legionella multiplication in water systems, disinfect potential sources of human exposure to legionella, and prevent health-care associated infections are beyond this guide's scope. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See 7.3 and 8.5 for specific hazard statements. ====== Significance And Use ====== 5.1 Water systems may be inspected (see Section 7 ) and tested (see Section 8 ) for legionella under three circumstances ( 1 ) in the absence of reported legionellosis (see 5.2 ); ( 2 ) when a single legionellosis case has been reported (see 5.3 ); and ( 3 ) when two or more legionellosis cases are reported in a limited time period and geographic region (see 5.4 ). Following are factors building owners and operators need to understand when considering testing water systems for legionella in the absence of illness (see 5.2 ) and for single legionellosis cases (see 5.3 ). Refer also to the CDC 2003 Guidelines for Preventing Health-Care Associated Pneumonia, and the CDC 2000 Guidelines for Preventing Opportunistic Infections Among Hematopoietic Stem Cell Transplant Recipients, and the WHO Legionella and the Prevention of Legionellosis. Detection of legionella in a water system is not sufficient to identify the system as a health hazard. However, failure to detect legionella does not indicate, conclusively, that the bacterium is not present (see 6.2.4 ) or that the water system may not pose a potential health hazard. Methods to detect legionella vary in sensitivity and specificity (see 6.2 ), and laboratories vary in their skill and experience in the isolation and identification of legionella. Isolation of apparently identical legionellae from clinical and environmental samples (see 6.2.1 , 6.6.2.4 , and Section 8 ) may suggest that a water system was the source of the legionella responsible for a patient's infection (see 5.3.2 ). However, cases of Legionnaires' disease due to different legionella serogroups or species need not necessarily have different sources of exposure because a system may be contaminated by more than one legionella. Timely inspection, testing, and treatment of possible legionella sources may reduce legal liabilities for facility owners and operators. Refer also to the APHA Public Health Law Manual. 5.2 Environmental Testing for Legionella in the Absence of Illness: 5.2.1 Concerned employers, building owners and operators, facility managers, and others seek to prevent real and potential health hazards, if possible. Water system operators may identify undesirable situations by monitoring routinely for legionella and may be able to implement control measures before the bacterium reaches an amount sufficient to cause human illness (see 6.2.4.2 ). The CDC 2000 Guidelines for Preventing Opportunistic Infections Among Hematopoietic Stem Cell Transplant Recipients advises that because transplant recipients are at much higher risk for disease and death from legionellosis compared with other hospitalized persons, periodic culturing for legionella in water samples from a center's potable water supply could be regarded as part of an overall strategy for the prevention of Legionnaires' disease in transplant centers and other facilities housing persons at high risk of infection if exposed (see 6.4.2 ). There is some evidence that environmental legionella surveillance should be considered a proactive strategy for the prevention of hospital-acquired Legionnaires’ disease ( 1 ). However, the optimal methodology (that is, frequency or number of sites) for environmental surveillance cultures in transplant centers has not been determined, and the cost-effectiveness of such a strategy has not been evaluated for either transplant centers or other health-care settings nor for institutional, commercial, or residential buildings. 5.2.2 Some experts advise against testing water systems for legionella in the absence of illness, particularly in buildings other than hospitals or health-care facilities, given that absolute exclusion of this bacterium from water systems may not be necessary to prevent legionellosis nor may it be achievable without considerable expense. Microbiological water monitoring increases operational costs, and interpretation of test results may be difficult (see 6.2.4 ). Identification of legionella in environmental samples also may cause unwarranted alarm and unnecessary remediation. The WHO publication states that legionella testing cannot be considered a control measure, but does provide some evidence that the water safety plan is effective and that control measures are operating properly. Sampling for legionella cannot provide results sufficiently quickly to be useful in operational monitoring, which instead should be by measures that provide real-time results, for example, monitoring of the biocide concentration, temperature, and pH of the water. 5.3 Environmental Testing for Legionella for a Single (Sporadic) Legionellosis Case: 5.3.1 Testing potential legionella sources as soon as possible after confirmation of legionellosis may increase the likelihood of identifying the responsible source. Environmental conditions and equipment operation may change frequently, which may affect the likelihood of legionella detection. Inspectors may fail to identify the responsible source if they postpone sampling until an illness is confirmed as legionellosis (see 6.6 and 6.7 ) or until a search for other cases identifies common exposures (see Section 9 ). 5.3.2 Persons with legionellosis often have been exposed to more than one possible source during the disease's incubation period (see 6.4.3 , 6.5.3 ) and may not recognize or recall all possible exposures. Isolation of apparently identical legionellae from clinical and environmental samples (see 6.2.1 , 6.6.2.4 , and Section 8 ) is suggestive, but does not identify a source absolutely as the site of a patient's exposure because the distribution of legionella species, serogroups, and subtypes (see 6.1.1 and 6.1.2 ) in the environment is not known, that is, the same legionella could colonize more than one water system. Identification of the environmental source responsible for legionella transmission may be difficult if no clinical isolate is available for comparison with environmental isolates (see 6.2.1 , 6.6.2.4 ). Legionella has been found in a substantial proportion of water systems tested in prevalence surveys and outbreak investigations. Without a clinical isolate, identification of the probable source of legionella transmission must be based on environmental and epidemiological information (see Sections 7 – 9 ). 5.4 Environmental Testing for Legionella for Multiple Legionellosis Cases— Identification of multiple legionellosis cases in a circumscribed area and limited time period or that share a potential source warrants ( 1 ) environmental inspection of suspect sources to identify the water system responsible for legionella transmission to prevent further illness (see Sections 7 – 9 ); and ( 2 ) epidemiological investigation to identify common risk factors for cases (see 6.4.2 , 6.5.2 ). Information from an epidemiological investigation (see Section 9 ) often facilitates identification of specific environments the legionellosis patients shared and on which inspectors should focus attention (see Sections 7 and 8 ). Environmental testing supplements, but does not replace, inspection and prompt correction of identified problems (see Section 10 ) at all possible legionella sources regardless of whether or not legionella is detected or the potential source is implicated in patient exposure.