Effect of rainfall on Giardia and crypto

Abstract

Rainfall increases concentrations of Giardia and Cryptosporidium through its influence on turbidity, flow volume, and possibly other unidentified factors. An investigation of the variability of concentrations of Giardia cysts and Cryptosporidium oocysts in the Delaware River was conducted in 1996 at Trenton, N.J. A goal of the study was to examine the relationship between concentrations of Giardia and Cryptosporidium and a variety of more easily measured microbial, water quality, and meteorological parameters. A positive correlation (Spearman rank; p < 0.05) was demonstrated between concentrations of Giardia cysts or Cryptosporidium oocysts and 15 other parameters. Increased concentrations of Giardia and Cryptosporidium as well as a variety of other microorganisms were associated with rainfall. The effect of rainfall on parasite concentrations is due in part to increased particulate matter in the water column following surface runoff and resuspension of river bottom and storm drain sediment.

Impact of climate change on waterborne diseases

“…There are several examples of waterborne diseases outbreaks associated to excessive rainfall [31][32][33][34][35][36][37][38][39][40][41][42][43]. The largest reported waterborne disease outbreak in the United States, due to the presence of Cryptosporidium cists in drinking water, occurred in Milwaukee in 1993 and was related to heavy rainfall and associated runoff and consequent contamination of Milwaukee lake, the source of the waterworks of the area.…”

Climate variability and change in the United States: potential impacts on water- and foodborne diseases caused by microbiologic agents.

“…A subsequent study in 1995 still found 13% of finished treated water to be contaminated with Cryptosporidium oocysts (31). Correlations between increased rainfall and increased Cryptosporidium oocyst and Giardia cyst concentrations in river water have been reported (32).…”

“…Viruses were detected in open shellfish harvesting areas during this increase in rainfall. Antecedent rainfall (32) Cryptosporidium and Giardia concentrations in river; positively correlated with rainfall Red Lodge, Montana…”

“…As previously mentioned, many anecdotal reports suggest rainfall as a contributing factor to waterborne outbreaks and the association of rainfall with contamination of river water supplies (24,32). In September 1999 the largest reported waterborne associated outbreak of E. coli O157:H7 occurred at a fairground in the State of New York and was linked to contaminated well water (126).…”

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

“…Outros parâmetros que têm sido sugeridos como indicadores são: pólens, algas e esporos de fungos (11) . Entre os parâmetros físico-químicos, destacam-se a turbidez e a contagem de partículas em suspensão (12) . Nos últimos anos, esforços substanciais têm sido focalizados na investigação do uso de indicadores para otimizar o tratamento das águas de abastecimento na remoção de parasitos (5) .…”