Malaria epidemics and surveillance systems in Canada

Abstract

In the past decade, fluctuations in numbers of imported malaria cases have been seen in Canada. In 1997 to 1998, malaria case numbers more than doubled before returning to normal. This increase was not seen in any other industrialized country. The Canadian federal malaria surveillance system collects insufficient data to interpret these fluctuations. Using local (sentinel), provincial, federal, and international malaria surveillance data, we evaluate and interpret these fluctuations. Several epidemics are described. With an ever-increasing immigrant and refugee population of tropical origin, improved surveillance will be necessary to guide public health prevention policy and practice. The Canadian experience is likely to be generalizable to other industrialized countries where malaria is a reportable disease within a passive surveillance system.

Figure 1

McGill University Centre for Tropical Diseases malaria cases by year and origin (N = 553).

Figure 2

Relative rates of Plasmodium species (N = 553).

Figure 3

Provincial malaria rates for Québec, Ontario, and British Columbia (6,11, Colette Colin [Ministère de la santé et des services sociaux, Québec], pers. comm.; Lorraine Schiedel [Ontario Ministry of Health and Long Term Care], pers. comm.; Monica Naus [British Columbia Centre for Disease Control], pers. comm.; Carole Scott [Division of Disease Surveillance, Health Canada], pers. comm.).

Figure 4

Plasmodium species provincial trends (6,11, Colette Colin [Ministère de la santé et des services sociaux, Québec], pers. comm.; Monica Naus [British Columbia Centre for Disease Control], pers. comm.; Lorraine Schiedel [Ontario Ministry of Health and Long Term Care], pers. comm.).

Figure 5

Malaria surveillance of Québec province, McGill Centre for Tropical Diseases (TDC), and Québec quality assurance (QA) program (Colette Colin [Ministère de la santé et des services sociaux, Québec], pers. comm.).

Figure 6

Malaria cases/100,000 relative to 1990 (6,12–25,30, Carole Scott [Division of Disease Surveillance, Health Canada], pers. comm.).

Figure 7

Plasmodium vivax incidence relative to 1998 (6,11, Colette Colin [Ministère de la santé et des services sociaux, Québec], pers comm.; Monica Naus [British Columbia Centre for Disease Control], pers. comm.).