The Confederation of Bushwalking Clubs NSW Incorporated

Water-born Health Hazards
The source of this document is unknown.
It is presented solely for general interest, and readers are advised not to rely on it but to consult their own doctor.
Much more information is presented in the FAQ under Water Safety.

SUBJECT: CRYPTOSPORIDIUM

MAJOR SPECIES: C. parvum C. muris C. balleyl C. meleagoridis There are approximately another 15 Sub-species Size: 3 to 5 micron (approximately half the size of Guardia.) Occurrence: Worldwide in water sources Reproduction: Only in stomach - intestine section of a host Infection: Mainly through consumption of water which is contaminated with faeces. - Direct infection (human to human) is possible Symptoms: Diarrohoetic illness First identification: Tyzzer in 1907 Inactivation: Resistant at 1.5 ppm and more chlorine. Extremely resistant against known disinfection in general. The absence of turbidity or coliform bacteria is not an indication of the absence of Cryptosporidium. Important: Filtered Cryptosporidium on a filter surface do not necessarily die. Danger of contamination during cleaning in the form of cysts still able to reproduce within one year. General: This bug is just TOO BIG to ever pass through a typical good quality bushwalking filter element. On the other hand Micropur or any other disinfectants including chlorine are not effective against Cryptosporidium. Hence the great worry to water supply authorities.

INFORMATION BULLETIN DATE: 20-08-96 SUBJECT: CRYPTOSPORIDIUM CRYPTOSPORIDIOSIS is caused by the protozoan Cryptosporidium, long recognized as a pathogen in calves, but not known to infect humans until 1976. Since then, the number of reported cases has been increasing. This; is another example of a disease with particularly serious effects on immunosuppressed individuals, including those with AIDS. In otherwise healthy individuals, the organism causes intestinal distress of a short duration. Immune-deficient individuals however suffer from a severe life threaten diarrhoea that may last for months. Transmission is largely faecal-oral between humans. This is important when considering the impact on a town supplied by an affected water supply. However, a Zoonosis-type transmission from calves has been observed. Diagnosis is based on microscopic examination of faeces for Cryptosporidium oocysts, and acid-fat staining or fluorescent anti-body tests. At present there is no reliable treatment. It is now thought that Cryptosporidium may be responsible for up to 30% of diarrhoeal illness in underdeveloped countries. In AIDS patients and other immnunosuppressed persons, Cryptosporidium can cause respiratory and gallbladder infections and may be a major cause of death. The organism, which lives inside the cells lining thee small intestine, can be transmitted through the faeces of cows, rodents, DOGS and CATS. Waterborne and hospital acquired infections have also been reported. Inside the host cell each Cryptosporidium organism forms four (4) oocysts, each containing four (4) sporozoites. When the occyst ruptures, sporozoites may infect new cells in the host or be released with the faeces. Fact Sheets - Micro-organisms 2: Protozoa

CRYPTOSPORIDIUM SPECIES Fact Sheet No.14 Guideline No guideline value is set for Cryptosporidium species in drinking water. if detected in an epistemological or prospective study, action to control this organism may be necessary, and advice should be sought from the relevant health authority. General Description Until recently, Cryptosporidium was best known as a parasite of pasture animals, but it is now regarded as an important human pathogen. Cryptosporidium that infect mammals are believed to belong to two species, of which C. parvum causes disease in humans. It has a complex life cycle involving intra cellular development in the gut wall, with sexual and asexual reproduction. Thick-walled oocysts, shed in faeces, are responsible for transmission. Pasture run-off and human wastes are the most significant sources of contamination of water. Densities of oocysts have been reported as high as 140 000 per litre in raw sewage and 5800 per litre in surface water. Water-borne outbreaks have occurred in North America and Britain, infecting as many as 400 000 people (Mackenzie et al, 1994) Water is only one of several mechanisms by which the faecal-oral cycle can be completed. Transmission of Cryptosporidium also occurs by direct contact with a human carrier or by contact with infected farm animals and possibly domestic pets. Australian Significance There is less data on the incidence of infection by Cryptosporidium in Australia than there is for giardiasis. Outbreaks have been recorded in day-care nurseries, presumably spread from person to person (Cruickshank et al., 1988). In South Australia a major outbreak of Cryptosporidium infections was recorded in 1990/91 (Weinstein et al, 1993). Statistical analysis showed that people drinking rainwater were less frequently infected, and the pattern of this outbreak suggested multiple sources of infection. A mixed outbreak of infections by Cryptosporidium and Guardia in Victoria followed contamination of a private water supply by overflow from a septic tank (Lester, 1992). There is considerable potential for contamination of water in dairying areas. At present, it would be difficult to determine whether infections in such areas can be attributed solely to contact with animals, or whether drinking water might contribute as a vehicle of transmission. Treatment of drinking Water Cryptosporidium oocysts are extremely resistant to disinfection, with a significant percentage apparently surviving 24 hour exposure to 1000 rng/L chlorine (Smith et al., 1989). Protection of water catchments from contamination by human wastes and if possible by pasture animals should be a priority. Comprehensive treatment (including filtration) is essential for surface waters that include pasture run-off The small size of Cryptosporidium oocysts (4-6 Em) makes some filtration processes vulnerable to penetration. Operational procedures in water treatment plants should be carefully examined where Cryptosporidium oocysts are present in the raw water to ensure that there is minimal transfer of oocysts to the distribution system. Method of Identification and Detection. Detection of Cryptosporidium involves concentration of relatively large volumes of water in several stages, fluorescent staining of the concentrated material, and examination using an ultraviolet microscope or an automatic cell counter (Bee et al., 1991). Several Australian laboratories have been developing methods for detecting Cryptosporidium, but processing individual samples is time-consuming and expensive. Routine monitoring for Cryptosporidium is not appropriate, but these methods will become important. in investigating sources of Infection. Prospective studies may also be valuable.