Graczyk Thaddeus K, Fried Bernard
Division of Environmental Health Engineering, Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA.
Adv Parasitol. 2007;64:111-60. doi: 10.1016/S0065-308X(06)64002-5.
Waterborne trematode and protozoan infections inflict considerable morbidity on healthy, i.e., immunocompetent people, and may cause life-threatening diseases among immunocompromised and immunosuppressed populations. These infections are common, easily transmissible, and maintain a worldwide distribution, although waterborne trematode infections remain predominantly confined to the developing countries. Waterborne transmission of trematodes is enhanced by cultural practices of eating raw or inadequately cooked food, socio-economical factors, and wide zoonotic and sylvatic reservoirs of these helminths. Waterborne protozoan infections remain common in both developed and developing countries (although better statistics exist for developed countries), and their transmission is facilitated via contacts with recreational and surface waters, or via consumption of contaminated drinking water. The transmissive stages of human protozoan parasites are small, shed in large numbers in feces of infected people or animals, resistant to environmental stressors while in the environment, and few are (e.g., Cryptosporidium oocysts) able to resist standard disinfection applied to drinking water.
水源性吸虫和原生动物感染会使健康人群（即免疫功能正常者）出现相当高的发病率，并且在免疫功能低下和免疫抑制人群中可能引发危及生命的疾病。这些感染很常见，易于传播，在全球范围内均有分布，不过水源性吸虫感染仍主要局限于发展中国家。食用生的或未充分煮熟食物的文化习俗、社会经济因素以及这些蠕虫广泛的人畜共患和野生动物宿主，都加剧了吸虫的水源性传播。水源性原生动物感染在发达国家和发展中国家都很常见（尽管发达国家有更好的统计数据），其传播通过接触娱乐用水和地表水或饮用受污染的饮用水而得以促进。人类原生动物寄生虫的传播阶段体积微小，大量存在于受感染的人和动物粪便中，在环境中对环境应激源具有抵抗力，而且很少有（如隐孢子虫卵囊）能够抵抗应用于饮用水的标准消毒措施。
