The reported incidence of waterborne disease is increasing in North America, and the provision of drinking water and sewage treatment is confronted with a growing population base and either an aging or developing infrastructure. To combat this trend, North American drinking water standards are continuously reviewed and increased effort is being expended to monitor and improve the quality of sewage and water treatment. in this regard Federal, Territorial and First Nation agencies have been working to improve community infrastructures within the Yukon. The Territory's location north of 60 degrees, cultural demographics, and the progress of First Nation self government initiatives, presents challenges in the delivery of these programs that are not encountered in southern Canada. A study of Yukon communities was conducted in 1995 to produce a current compilation of services as they existed at the time. A summary of the existing infrastructure, policy and program background, unique aspects of program delivery, and future development are examined.

Sixteen beluga whales (Delphinapterus leucas) and fifteen ringed seals (Phoca hispida) from the western arctic region of Canada were examined for giardiasis and cryptosporidiosis. Intestinal contents from the rectum and colon were collected from animals slaughtered by Inuit hunters. A fluorescent monoclonal antibody identified Giardia sp. cysts in three of 15 (20%) seals. Thus, ringed seals are implicated as a potential reservoir for this zoonosis in the arctic.

Several outbreaks of waterborne giardiasis have occurred in southern Canada, but nothing has been reported from the Canadian North. The objective of this study was to collect information relevant to waterborne giardiasis and cryptosporidiosis in the Yukon including epidemiological data and analyses of water, sewage, and animal fecal samples. Remote, pristine water samples were found to be contaminated with Giardia cysts (7 of 22 or 32%) but not with Cryptosporidium oocysts. Giardia cysts were found in 21% (13 of 61) of animal scats, but no Cryptosporidium oocysts were observed (small sample size). Whitehorse's drinking water was episodically contaminated with Giardia cysts (7 of 42 or 17%) and Cryptosporidium oocysts (2 of 42 or 5%). Neither were found in Dawson City's water supply. The only water treatment in the Yukon is chlorination, but contact times and free chlorine residuals are often too low to provide adequate protection by disinfection. Raw sewage samples from the five largest population centers in the Yukon contained 26 to 3,022 Giardia cysts and 0 to 74 Cryptosporidium oocysts per liter. Treated sewage from Whitehorse contained fewer Giardia cysts but more Cryptosporidium oocysts on average. Both were detected in Lake Laberge, downstream of Whitehorse, which has a history of fecal coliform contamination. Daily monitoring of raw sewage from the suburbs of Whitehorse showed a summertime peak of Giardia cysts and occasional Cryptosporidium oocysts after springtime contamination of drinking water. Despite this evidence, epidemiological data for the Yukon showed an endemic infection rate of only 0.1% for giardiasis (cryptosporidiosis is not notifiable).(ABSTRACT TRUNCATED AT 250 WORDS)

Metronidazole, tinidazole and dimetridazole were administered in the drinking water for 5 days to mice experimentally infected with Tritrichomonas muris and Tetratrichomonas microta. Mice were successfully infected with T. muris and T. microta recovered from infected gerbils. The trichomonas infection was successfully eliminated in mice given a 1% sucrose solution containing 2·5 mg/ml metronidazole or tinidazole. Mice receiving 1·0 mg/ml metronidazole, 1·0 mg/ml tinidazole and 1·2, 5·0 and 10·0 mg/ml dimetridazole failed to eliminate the trichomonas organism. A reduction in water intake was only noted with mice receiving 10 mg/ml dimetridazole. In mice receiving only 1% sucrose the infection was not eliminated.