三次水传播疾病的暴发被归因于隐孢子虫，其中两次与饮用水有关，第三次与地表水有关，但水传播疾病的风险尚不清楚，因为许多因素可能导致传播。在西部六个州采集的107个地表水样本中，77个对隐孢子虫卵囊的存在呈阳性。未经处理的污水中的卵囊数较高（1732个/L），而无废水排放的水中的卵囊数较低（0.04个/L）。饮用水中也检测到隐孢子虫。然而，关于卵囊在环境中或在污水和饮用水处理过程中存活的信息很少。有必要进行进一步研究，以确定影响水中可能存在传染性卵囊的变量。有人认为隐孢子虫的流行病学和传播与贾第虫相似。根据环境发生情况，隐孢子虫通过水道传播的风险可能等于或大于贾第虫。 包括50个参考文献、表格和图表。

Three outbreaks of waterborne disease have been attributed to Cryptosporidium--two linked to drinking water and a third to surface water-yet the risk of waterborne disease in unknown because many factors may contribute to transmission. Of 107 surface water samples collected in six western states, 77 were positive for the presence of Cryptosporidium oocysts. A high count was found in raw sewage (1,732 oocysts/L), whereas low counts were found in waters without waste discharges (0.04 oocysts/L). Cryptosporidium has also been detected in drinking water. Little information is available, however, on oocyst survival in the environment or during sewage and drinking water treatment processes. Further research is necessary to define the variables that will influence the possible presence of infectious oocysts in water. It has been suggested that the epidemiology and transmission of Cryptosporidium are similar to Giardia. Based on environmental occurrence, the risk of Cryptosporidium transmission by the water route may be equal to or greater than that of Giardia. Includes 50 references, tables, figure.