Other intestinal protozoa

Estimates for the prevalence of other intestinal parasites in Canada and Alaska are based on limited data from studies in selected populations. As has been reported worldwide, symptomatic infection with microsporidial species and Cryptosporidium parvum is closely associated with HIV/AIDS. No overall prevalence data are available for microsporidia but prevalence rates for Cryptosporidium can be striking in domestic animals such as sheep (23%) and cattle (20%) (Olson et al. 1997). Estimates of human infection range from 0.2 to 8% (Ratnam et al. 1985; Kabani et al. 1995). The ageing sewage and water infrastructure of many urban centres in Canada and Alaska likely puts them at risk for major outbreaks of cryptosporidiosis. Cyclosporiasis is not endemic in Canada or Alaska. Up until the summer of 1996, the rare cases reported were always associated with travel to the developing world. In the spring months of 1996 and 1997 in both Canada and the United States epidemics of cyclosporiasis have been reported. The first outbreak was thought to have been caused by the importation

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of contaminated raspberries from Guatemala (Herwaldt and Ackers 1997). Little is known about the epidemiology of Dientamoeba fragilis in Canada or Alaska other than the fact that it is present in selected population sub-groups (e.g. daycare centre staff and children) (Keystone et al. 1984). The presence of non-pathogenic intestinal protozoa has not been systematically studied in Canada or Alaska. Data from large provincial laboratories show rates similar to those in other industrialized countries. There has been no systematic effort to study the prevalence of Trichomonas vaginalis in Canada or Alaska. Prevalence rates have ranged from 0% in 57 Qu├ębec women with dysparunia (Bazin et al. 1994) to 7.3% for women attending an STD clinic in Nova Scotia between 1983 and 1985 (Pereira et al. 1990).

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