Epidemiological and clinical description of the top three reportable parasitic diseases in a Canadian community

Abstract

This study provides a comprehensive epidemio-clinical picture of sporadic, domestically acquired cases of amoebiasis, cryptosporidiosis and giardiasis in one Canadian community based on patient symptom, outcome and exposure data from an enhanced surveillance system. It yields valuable data for estimating the burden of those diseases including the proportion of bloody diarrhoea, hospitalization, and disease duration. Age differences were observed by incidence rate and for some clinical information and exposures to risk factors. For each of the three diseases, the animal/environment-to-person route was the most common possible main transmission route according to the exposure reported, whereas the person-to-person route was the least common. Exposure was higher for the 10-24 years age group of giardiasis cases for swimming in recreational waters (79%) and attending a barbeque (50%). Therefore, comparisons between groups of cases or extrapolation of results when estimating the burden of illness should be adjusted for age.

Fig. 1.

Age- and gender-specific incidence rate of sporadic, domestically acquired (a) amoebiasis, (b) cryptosporidiosis and (c) giardiasis cases reported in the Region of Waterloo, June 2005–May 2009. The differences between age groups are shown for males and females together as the relative incidence rate with the 40–59 years age group being the reference. (Note a log scale was chosen for its scale on the right because of large differences between age groups and because of the width of some confidence intervals.)

Fig. 2.

Symptoms and exposures (% with 95% confidence intervals) for which there were statistically significant age differences in reported giardiasis cases in the Region of Waterloo, Ontario, June 2005–May 2009.