Recent Trends in Legionella and Waterborne Disease Outbreaks and Their Causes

Every day, over 50,000 community water systems serve treated (finished) drinking water to over 300 million Americans, while almost 45 million rely onprivate wellsfor some or all of their water. The availability of safe drinking water is vital to public health, but contamination can occur and treatment, storage, and distribution systems can fail. When one or more happen—especially at the same time—the result can be a drinking water-associated disease outbreak. And according to theUS Centers for Disease Control and Prevention（CDC），爆發的主要原因仍然吸入Legionellabacteria (legionellosis),Public Health Enemy #1 in US Water Systems。

Waterborne Disease Outbreak Reporting: 2013–2014

Public health agencies in the states and territories report information on waterborne disease outbreaks to the CDC through the National Outbreak Reporting System (nors.), which are collected and analyzed under the Waterborne Disease and Outbreak Surveillance System (WBDOSS)¹。2017年末，Katharine M.本尼迪克特，DVM，博士和同事刊登了他們對2013 - 2014年報告的爆發分析的結果。²

During that period, a total of 42 drinking water-associated outbreaks were reported, accounting for at least 1,006 cases of illness, 124 hospitalizations, and 13 deaths (see Figure 1 below).Once again,Legionellawas the most common cause of reported outbreaks, accounting for over half (57%) of outbreaks和all of the deathsduring the most recent assessment period.³Together, chemicals/toxins and parasites accounted for 29% of outbreaks and 79% (788) cases of illnesses. Notably, eight outbreaks caused by parasites resulted in 289 (29%) cases, of which 279 (97%) were caused byCryptosporidium.和10 (3%) byGiardia。化學品或毒素在四種爆發中涉及499例，13例住院治療 - 包括與藻類相關的第一個報告的爆發。然而，重要的是要認識到WBDOSS係統的局限性，包括偶然會發生水性疾病的案例，或作為未報告的疾病爆發的一部分。

Behind the Numbers: Legionella and Water System Deficiencies

Figure 2 summarizes information on water system deficiencies associated with outbreaks in 2013–2014. Using available data, each outbreak is assigned to one or more deficiency classifications. For example, for outbreaks caused byLegionella, the bacteria were identified inside building (“premise”) plumbing systems.

雖然Legionella可以引起一種潛在致命的肺炎（Legionnaires'疾病）的形式，它也可以引起呼吸疾病（豬瘟）的更溫和的形式。⁴Both illnesses can result from inhaling water mists or vapors from hot water systems contaminated withLegionellabacteria, as well asdecorative fountains和冷卻塔。重要的是要強調，軍團警告症疾病和龐蒂亞克熱病都沒有與攝入飲用水直接相關，但通常與通過熱水管道（例如淋浴）吸入霧或蒸汽有關biofilm, scale, and favorable temperature can foster growth and proliferation ofLegionella。相比之下，大多數疾病爆發急性胃腸疾病（導致嚴重腹瀉的AGI）是由直接消耗飲用水引起的，這些飲用水是由低或沒有的係統的病原體汙染chlorine residuals。New researchthat evaluated an outbreak of Legionnaires’ disease that killed 12 people and sickened at least 87 in Flint, Michigan, in 2014 and 2015 found “During the crisis, as the concentration of free chlorine in water delivered to Flint residents decreased, their risk of acquiring LD increased.” Mounting concerns withLegionellaarespurring state-level efforts增加氯殘留減少國際扶輪sk of these outbreaks.

The Future of Waterborne Disease Reporting and Prevention

美國飲水社區的安全飲水法規並由聯邦bob体育贴吧，國家，部落和地方政府和公用事業提供支持，被廣泛認可為我們國家最重要的公共衛生提升之一。但是，當發生爆發時，細節的分析有助於了解爆發的根本原因以及降低未來事件的風險。有效的水處理和法規，與快速檢測，爆發報告和鑒定以及原因的鑒定有助於保護公共飲用水供應，並提高減少致病微生物和有害化學品和毒素的傳播造成的風險的追求。

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¹WBDOSS was initiated in 1971 as a partnership between the CDC, the Council of State and Territorial Epidemiologists, and the US Environmental Protection Agency. Although initially designed to collect data about US drinking water outbreaks, WBDOSS also covers outbreaks associated with recreational water and other non-recreational water exposures.

²CDC. 2017. Surveillance for Waterborne Disease Outbreaks Associated with Drinking Water — United States, 2013–2014.https://www.cdc.gov/mmwr/volumes/66/wr/mm6644a3.htm.。

³雖然outbreaks of legionellosis are reported through WBDOSS, it is anationally notifiable disease。

⁴CDC. 2018.Legionella（Legionnaires'疾病和龐氏症）。https://www.cdc.gov/legionella/。