ENVIRONMENTAL ECOLOGY OF CRYPTOSPORIDIUM AND PUBLIC HEALTH IMPLICATIONS

Abstract

Cryptosporidium has become the most important contaminant found in drinking water and is associated with a high risk of waterborne disease particularly for the immunocompromised.There have been 12 documented waterborne outbreaks in North America since 1985; in two of these (Milwaukee and Las Vegas) mortality rates in the immunocompromised ranged from 52% to 68%.The immunofluorescence antibody assay (IFA) using epifluorescence microscopy has been used to examine the occurrence of Cryptosporidium in sewage (1 to 120 oocysts/liter), filtered secondary treated wastewater (0.01 to 0.13 oocysts/liter), surface waters (0.001 to 107 oocysts/liter), groundwater (0.004 to 0.922 oocysts/ liter) and treated drinking water (0.001 to 0.72 oocysts/liter).New rules are being developed (Information Collection Rule and Enhanced Surface Water Treatment Rule) to obtain more occurrence data for drinking water systems for use with new risk assessment models. Public health officials should consider a communication program to physicians treating the immunocompromised, nursing homes, develop a plan to evaluate cases of cryptosporidiosis in the community, and contribute to the development of public policies that limit contamination of source waters, improve water treatment, and protect public health.

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

“…However, because of a preceding period of heavy rainfall and runoff, there was a decrease in raw water quality along with a diminished effectiveness of the system's coagulation-filtration process, which in turn led to increased turbidity of the treated water and inadequate removal of the oocysts (20,21). Other waterborne cryptosporidiosis outbreaks have been reported worldwide, and rainfall has been mentioned as playing a role in a number of them (22)(23)(24).…”

“…parvum is a common cause of diarrhea in AIDS patients in both the developed and developing worlds, with reported prevalence rates of 3.6% in the United States to about 50% in Africa (24). One year after the Milwaukee episode, a cluster of cryptosporidiosis cases and deaths among AIDS patients in Las Vegas (Clark County), Nevada, alerted health officials to another waterborne outbreak (25).…”

“…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).…”

“…It is now known that certain emerging pathogens can pass through existing filtration and disinfection systems, among them Cryptosporidium. Water chlorination, a widely used method of disinfection, is not as efficient as ozone for inactivating the Cryptosporidium oocysts (24).…”

Longitudinal Evaluation of Enteric Protozoa in Haitian Children by Stool Exam and Multiplex Serologic Assay

“…However, in immunocompromised individuals, such as those with human immunodeficiency virus (HIV), cryptosporidiosis can cause a mortality rate as high as 68%, a major burden in Africa, where HIV prevalence is as high as 30%. 2 In Africa, Asia, and Latin America, it has been estimated that G. intestinalis infects 200 million people. 3 In contrast to developed countries, many people in undeveloped countries with infections of G. intestinalis do not develop symptoms.…”