Table 1. Tick-borne pathogens that are present in or may spread to Canada.
| Pathogen | Year of ID | Principal tick vector(s) | Principal reservoir host species | Geographic distributiona | Nationally notifiable | Detection in Canada | |||
|---|---|---|---|---|---|---|---|---|---|
| Canada | US | Tick | Human | Animal | |||||
| Anaplasma phagocytophilum | 1994 | Ixodes scapularis, Ixodes pacificus | Rodents | BC, AB, SK, MB, ON, QC, NB, NL, NS, PEI | Upper MW and NE states | No | Yes | Yes | Yes |
| Babesia microti | 1970 | Ixodes scapularis | Mice | MB, ON, QC, NB, NS | NE and upper MW states | No | Yes | Yes | Yes |
| Borrelia burgdorferi | 1982 | Ixodes scapularis, Ixodes pacificus | Rodents | BC, AB, SK, MB, ON, QC, NB, NS, NL, PEI | NE and upper MW states | Yes | Yes | Yes | Yes |
| Borrelia hermsii | 1935 | Ornithodoros hermsi | Rodents and rabbits | BC | Western states | No | --- | Yes | --- |
| Borrelia mayonii/ Borrelia mayonii-like | 2014 | Ixodes scapularis/Ixodes angustus | Rodents | ON, BC | Upper MW states: Minnesota and Wisconsin | No | Yes | --- | Yes |
| Borrelia miyamotoi | 2013 | Ixodes scapularis, Ixodes pacificus | Mice | BC, AB, MB, ON, QC, NB, NS, NL, PEI | Upper MW, NE, and the Mid-Atlantic states | No | Yes | No | --- |
| Colorado tick fever virus | 1946 | Dermacentor andersoni | Golden mantled squirrels, deer mice and rabbits | SK, AB | Western states: Colorado, Utah, Montana, Wyoming | No | No | Yes | --- |
| Ehrlichia chaffeensis | 1987 | Amblyomma americanum | White-tailed deer | --- | Southeastern and South Central states | No | No | No | --- |
| Ehrlichia ewingii | 1999 | Amblyomma americanum | White-tailed deer | --- | Southeastern and South Central states | No | --- | --- | --- |
| Ehrlichia muris-like agent | 2011 | Ixodes scapularis/ Ixodes muris | Mice | MB | Upper MW states | No | Yes | --- | --- |
| Francisella tularensis | 1924 | Dermacentor variabilis, Dermacentor andersoni, Amblyomma americanum | Rabbits, hares, and rodents | Canada wide | All states | Yes | Yes | Yes | Yes |
| Heartland virus | 2012 | Amblyomma americanum | White-tailed deer | --- | MW and South states | No | No | --- | --- |
| Lineage I Powassan virus | 1963 | Ixodes cookei, Ixodes marxi, Ixodes spinipalpis | Small and medium-sized woodland mammals (woodchucks) | ON, QC, NB, PEI | NE states and Great Lakes region | No | Yes | Yes | Yes |
| Lineage II Powassan virus | 2001 | Ixodes scapularis, Dermacentor andersoni | Mice | MB, ON, NS | NE and upper MW states | No | Yes | --- | --- |
| Rickettsia rickettsii | 1909 | Dermacentor variabilis, Dermacentor andersoni, Rhipicephalus sanguineus | Variety of wild mammals including rodents | BC, AB, SK, ON, NS | Eastern, Central, Western and Southwestern states | No | Yesb | Yesb | Yes |
Abbreviations: AB, Alberta; BC, British Columbia; MB, Manitoba; MW, Midwestern; NB, New Brunswick; NE, Northeastern; NL, Newfoundland and Labrador; NS, Nova Scotia; ON, Ontario; PEI, Prince Edward Island; QC, Quebec; SK, Saskatchewan; US, United States
Adapted from Paddock et al. 2016 (44)
a Canada: Provinces where endemic transmission is known to occur are in bold. For provinces that are not in bold, local pathogen transmission cycles have not been clearly defined and/or infections were detected in adventitious ticks, and/or in humans or animals. US: States where highest incidence rate of human cases were found
b based on historical surveys in ticks in Canada and not recent surveys; human cases of Rocky Mountain spotted fever are also historical; recent cases of spotted fever group Rickettsia have been documented but are rare
(-) indicates no data available and/or no studies have been performed