US outbreaks of cryptosporidiosis

Abstract

An overview of US cryptosporidiosis outbreaks suggests that conventional treatment processes operated at minimum regulatory compliance levels are ineffective at preventing transmission of the disease. Drinking water has been implicated as the mode of transmission in several outbreaks of cryptosporidiosis throughout the United States. This review of US outbreaks describes characteristics of the raw water supply, suspected sources of contamination, water treatment methods, and corrective actions. Of the total number of outbreaks, roughly half were associated with groundwater sources; the majority of affected individuals, however, were served by drinking water drawn from surface water. Wastewater was implicated as the source of contamination of raw or treated water for roughly half of the outbreaks. Nonpoint sources, such as agricultural runoff, were suspected sources of contamination in the remaining outbreaks. The majority of affected individuals were served by treatment plants using coagulant addition, filtration, and chlorine disinfection processes. Although treatment deficiencies and suboptimal operational practices were noted during some of the outbreaks, all treatment plants were complying with federal and local regulations. Existing regulations and water supply systems, especially those utilizing surface water sources, should be reevaluated.

Avaliação da água do sistema de abastecimento municipal de Maringá, PR, com relação à possível ocorrência de Cyptosporidium sp. e Giardia sp.

“…No presente estudo, as concentrações de coliformes, encontradas nas amostras de água in natura, coincidem com os valores observados por alguns autores para amostras em que foram detectadas correlações estatísticas significativas entre a presença destes protozoários e os parâmetros microbiológicos (14,15) . Porém, a utilização de coliformes na previsibilidade de presença e/ou ausência de parasitos, no ambiente aquático, vem sendo discutida, pois há relatos de vários surtos de gastroenterites associados ao consumo de água bacteriologicamente potável (16,17) . O exemplo mais noticiado foi o surto de criptosporidiose de Milwaukee (Wisconsin, EUA), em 1993, onde mais de 400.000 pessoas foram infectadas, com mais de 100 óbitos, mesmo estando a água final em completa conformidade com os requerimentos regulatórios (17) .…”

“…Porém, a utilização de coliformes na previsibilidade de presença e/ou ausência de parasitos, no ambiente aquático, vem sendo discutida, pois há relatos de vários surtos de gastroenterites associados ao consumo de água bacteriologicamente potável (16,17) . O exemplo mais noticiado foi o surto de criptosporidiose de Milwaukee (Wisconsin, EUA), em 1993, onde mais de 400.000 pessoas foram infectadas, com mais de 100 óbitos, mesmo estando a água final em completa conformidade com os requerimentos regulatórios (17) . Entretanto, os coliformes destacam-se como indicadores da qualidade da água, por serem microrganismos quantificáveis por métodos laboratoriais rápidos e simples.…”

Association between the concentration of protozoa and surrogates in effluents of the slow sand filtration for water treatment

“…This fact becomes more evident when the occurrence of outbreaks of waterborne diseases is associated with water that meets all regulatory requirements. The most famous example was the outbreak of cryptosporidiosis in Milwaukee (Wisconsin, USA), in 1993, when over 400,000 people were infected, and over 100 died (10,20,21).…”

Active, multisite, laboratory-based surveillance for Cryptosporidium parvum.

“…1 In 1993, a massive outbreak of cryptosporidiosis in Milwaukee, Wisconsin, associated with contaminated city drinking water, made approximately 400,000 persons ill. 2 In the United States, outbreaks have also been associated with drinking water, recreational water use, consumption of contaminated foods, contact with animals, and child care attendance. [3][4][5][6][7][8] These outbreaks have heightened the awareness of cryptosporidiosis in this country.…”