West Nile virus and other mosquito-borne disease national surveillance report 2014

2014 - Final - Summary

West Nile Virus in Canada

Humans: During the 2014 West Nile virus season, three provinces (Manitoba, Ontario and Quebec) reported human cases of West Nile virus to the Public Health Agency of Canada. No fatalities were reported.

A total of 21 human clinical cases of West Nile virus were reported in Canada: five in Manitoba [Interlake-Eastern Health Region (1), Prairie Mountain Health Region (2)Footnote *, Southern Health Region (1) and Winnipeg Health Region (1)], 10 in Ontario [Chatham-Kent (1), Halton Region (2), Lambton County (1), City of Ottawa (2), Simcoe-Muskoka District (1) and City of Toronto (3)] and six in Quebec [Lanaudière (1), Montérégie (3) and Montreal (2)].

Of the 21 human clinical cases, 10 (47.6%) were classified as West Nile virus non-neurological syndrome, nine (42.9%) as West Nile virus neurological syndrome and two (9.5%) as unclassified/unspecified.

One asymptomatic infection was reported in Ontario: Windsor-Essex County.

Mosquitoes: A total of 219 mosquito pools tested positive for West Nile virus in Canada: 24 in Manitoba [Interlake-Eastern Health Region (7), Prairie Mountain Health Region (1), Southern Health Region (11) and Winnipeg Health Region (5)]; 56 in Ontario [Haliburton-Kawartha-Pine Ridge District (1), Halton Regional (3), City of Hamilton (7), Lambton (1), Middlesex-London (4), Niagara Regional (2), City of Ottawa (3), Peel Regional (22), City of Toronto (10), Windsor-Essex County (1) and York Regional (2)]; 119 in Quebec [Laval (13), Montérégie (42) and Montreal (64)] and 20 in Saskatchewan [Sun Country, Regina Qu'Appelle, Five Hills, Cypress, Heartland Health Regions].

Dead Birds: The Canadian Wildlife Health Cooperative tested a total of 130 dead birds for West Nile virus in Canada: Manitoba (1), Northwest Territories (1), Ontario (31), Quebec (26) and Saskatchewan (71).

Of these, 18 (13.8%) dead birds tested positive for West Nile virus in Canada: Ontario (6), Quebec (10) and Saskatchewan (2).

Domestic Animals: The Canadian Food Inspection Agency reported a total of 21 horses tested positive for West Nile virus in Canada: Alberta (7), Manitoba (1), Ontario (1), Quebec (4) and Saskatchewan (8).

West Nile Virus Human Disease Cases in the United States

As of January 13, 2015, the Centers for Disease Control and Prevention (CDC) reported 2,122 West Nile virus human disease cases:

Alabama (2), Arizona (104), Arkansas (11), California (787), Colorado (114), Connecticut (6), District of Columbia (3), Florida (16), Georgia (12), Idaho (18), Illinois (40), Indiana (9), Iowa (15), Kansas (51), Kentucky (1), Louisiana (111), Maryland (6), Massachusetts (6), Michigan (1), Minnesota (21), Mississippi (43), Missouri (13), Montana (5), Nebraska (140), Nevada (3), New Jersey (7), New Mexico (24), New York (22), North Dakota (22), Ohio (11), Oklahoma (18), Oregon (8), Pennsylvania (12), South Carolina (2), South Dakota (57), Tennessee (15), Texas (353), Utah (2), Virginia (7), Washington (12), Wisconsin (7) and Wyoming (5).

Of these, 1,283 (60.5%) were diagnosed as neuroinvasive disease cases and 839 (39.5%) as non-neuroinvasive disease cases. Eighty-five fatal cases were reported. Three hundred and thirty-seven presumptive viremic blood donors have been identified.

West Nile Fever in the European Union, European Economic Area and Neighbouring Countries

As of November 20, 2014, the European Centre for Disease Prevention and Control (ECDC) reported a total of 74 human cases of West Nile fever in Europe: Austria (1), Greece (15), Hungary (11), Italy (24) and Romania (23). In the neighbouring countries and regions, a total of 136 human cases have been reported: Bosnia and Herzegovina (13), Gaza (1), Israel (17), Russian Federation (29) and Serbia (76).

Figure 1. West Nile Virus clinical cases and asymptomatic infections, by Province/Territory and report week, 2014 season

* West Nile virus clinical cases and asymptomatic infections are grouped by report week, based on episode date. Episode date could include one of the following: onset date, diagnosis date, lab sample date or reporting date.

Table 1: West Nile Virus clinical cases and asymptomatic infections, by Province/Territory and report week, 2014 season
Provinces and Territories Report week of 2014
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44
Newfoundland and Labrador 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Prince Edward Island 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Nova Scotia 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
New Brunswick 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Quebec 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 1 0 0 1 0 0 0
Ontario 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 2 0 2 5 1 0 0 0 0 0 0 0
Manitoba 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1Table 1 - Footnote ** 2 2 0 0 0 0 0 0 0 0 0
Saskatchewan 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Alberta 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
British Columbia 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Yukon Territory 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Northwest Territory 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Nunavut 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Total 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 4Table 1 - Footnote * 3 5 6 1 1 0 0 1 0 0 0
Table 1 - Footnote *

One of these cases was likely exposed prior to the 2014 West Nile virus season.

Return to table 1 - footnote * referrer

Table 1 - Footnote **

This case was likely exposed prior to the 2014 West Nile virus season.

Return to table 1 - footnote ** referrer

Table 2: West Nile Virus human clinical cases and asymptomatic infections by Province/Territory, 2014 season
Provinces and Territories Year to date: January 1 to November 1, 2014
West Nile virus neurological syndrome West Nile virus non-neurological syndrome Unclassified/ unspecified Total clinical
casesTable 2 - Footnote 1
Number of travel-related casesTable 2 - Footnote 2 West Nile virus asymptomatic infectionsTable 2 - Footnote 3
Newfoundland and Labrador 0 0 0 0 0 0
Prince Edward Island 0 0 0 0 0 0
Nova Scotia 0 0 0 0 0 0
New Brunswick 0 0 0 0 0 0
Quebec 5 1 0 6 0 0
Ontario 3 5 2 10 2 1
Manitoba 1 4Table 2 - Footnote * 0 5Table 2 - Footnote * 0 0
Saskatchewan 0 0 0 0 0 0
Alberta 0 0 0 0 0 0
British Columbia 0 0 0 0 0 0
Yukon Territory 0 0 0 0 0 0
Northwest Territory 0 0 0 0 0 0
Nunavut 0 0 0 0 0 0
Total 9 10Table 2 - Footnote * 2 21Table 2 - Footnote * 2 1
Table 2 - Footnote 1

Total clinical cases is the sum of both probable and confirmed: West Nile virus neurological and non-neurological syndromes, along with any unclassified or unspecified cases.

Return to table 2 - footnote 1 referrer

Table 2 - Footnote 2

Likely related to travel outside the Province/Territory. These cases are included in either the total clinical cases or West Nile virus asymptomatic infections.

Return to table 2 - footnote 2 referrer

Table 2 - Footnote 3

Satisfies West Nile virus diagnostic test criteria in the absence of clinical criteria. This category could include asymptomatic blood donors whose blood is screened using a nucleic acid amplification test, by blood operators (i.e. Canadian Blood Services or Hema-Quebec) and is subsequently brought to the attention of public health officials. Blood operators in Canada perform a supplementary West Nile virus specific nucleic acid amplification test following any positive donor screen test result.

Return to table 2 - footnote 3 referrer

Table 2 - Footnote *

One of these cases was likely exposed prior to the 2014 West Nile virus season.

Return to table 2 - footnote * referrer

Figure 2. West Nile Virus clinical cases and asymptomatic infections by report week for selected years

* West Nile virus clinical cases and asymptomatic infections are grouped by report week, based on episode date. Episode date could include one of the following: onset date, diagnosis date, lab sample date or reporting date.
Table 3: West Nile Virus clinical cases and asymptomatic infections by report week for selected years
Year Report week
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
2014 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 4Table 3 - Footnote * 3 5 6 1 1 0 0 1 0 0 0 - - -
2013 1 0 0 0 0 1 1 0 0 0 1 2 1 5 5 8 17 11 13 13 11 9 1 6 1 0 4 1 0 1 0
2012 1 0 0 0 0 0 0 0 0 0 3 5 11 16 27 53 63 57 43 43 45 24 30 14 9 5 1 0 0 0 0
2007 0 0 0 0 0 0 2 2 3 4 11 35 36 72 139 424 471 443 287 182 116 71 30 18 10 11 5 4 2 0 0
2005 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 4 11 28 28 38 45 27 15 7 12 3 3 1 0 0 0
2003 0 0 0 0 0 0 0 0 0 1 1 1 5 11 9 27 66 249 323 324 178 107 82 37 14 8 4 3 0 0 0
Table 3 - Footnote *

One of these cases was likely exposed prior to the 2014 West Nile virus season.

Return to table 3 - footnote * referrer

Table 4.1: Reported cumulative number of West Nile Virus positive mosquito pools by Province/Territory and by report week, 2014 season Table 4.1 - Footnote *
Provinces and Territories Report week of 2014
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44
Newfoundland and Labrador 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Prince Edward Island 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
New Brunswick 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Nova Scotia 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Quebec 0 0 0 0 0 0 0 0 0 0 0 0 1 4 9 10 19 19Table 4.1 - Footnote ** 39 70 99 112 119 119 119 119 119 119
Ontario 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 9 11 13 30 43 52 56 56 56 56 56 56 56
Manitoba 0 0 0 0 0 0 0 0 0 0 0 0 0 0 7 7 14 19 22 24 24 24 24 24 24 24 24 24
Saskatchewan 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 2 9 19 20 20 20 20 20 20 20 20 20 20
Alberta 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
British Columbia 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Yukon Territory 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Northwest Territory 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Nunavut 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Total 0 0 0 0 0 0 0 0 0 0 0 0 1 7 22 28 53 70 111 157 195 212 219 219 219 219 219 219
Table 4.1 - Footnote *

Detailed West Nile virus mosquito surveillance data can be accessed through Provincial/Territorial websites.

Return to table 4.1 - footnote * referrer

Table 4.1 - Footnote **

Week 34 data was not available at the time of publication.

Return to table 4.1 - footnote ** referrer

Table 4.2: Number of mosquito pools tested and number of positive mosquito pools by Province/Territory, 2014 season
Provinces and Territories Year to date: January 1 to November 1, 2014
Number of positive mosquito pools Number of mosquito pools tested Percentage of positive mosquito pools (%)
Quebec 119 11,413 1.0
Ontario 56 14,116 0.4
Manitoba 24 1,505 1.6
Saskatchewan 20 824 2.4
British Columbia 0 236 0
Total 219 28,094 0.8

Figure 3. Reported number of dead birds testing positive for West Nile Virus, by Province/Territory and report week, 2014 seasonFigure 3 - Footnote *

Table 5: Reported number of dead birds testing positive for West Nile Virus, by Province/Territory and report week, 2014 season Table 5 - Footnote *
Provinces and Territories Report week of 2014
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 Total
Newfoundland and Labrador 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Prince Edward Island 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
New Brunswick 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Nova Scotia 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Quebec 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 1 0 3 2 0 1 0 1 0 0 0 0 0 0 10
Ontario 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 3 0 0 1 0 0 0 0 0 0 0 0 0 0 6
Manitoba 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Saskatchewan 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2
Alberta 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
British Columbia 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Yukon Territory 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Northwest Territory 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Nunavut 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Total 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 4 0 3 3 0 1 0 1 0 0 0 0 0 0 18

Figure 4. Percentage of dead birds testing positive for West Nile Virus in the 2014 season by report week, as compared to the 2003, 2012 and 2013 seasons

Table 6: Percentage of dead birds testing positive for West Nile Virus in the 2014 season by report week, as compared to the 2003, 2012 and 2013 seasons
  Report week of 2014
17 18 19 20 21 22 23 24 26 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
Numbers positive 2014 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 4 0 3 3 0 1 0 1 0 0 0 0 0 0
Numbers tested 2014 0 0 0 0 0 0 0 0 0 0 0 0 0 43Table 6 - Footnote * 10 13 10 7 13 6 11 4 1 5 3 2 0 0 1 0 0 1
Percentage positive 2014 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 20 29 31 0 27 75 0 20 0 50 0 0 0 0 0 0
Numbers positive 2013 0 0 0 0 0 0 0 0 0 1 0 0 5 2 13 9 6 6 18 9 6 6 2 0 1 0 0 0 0 0 0 0
Numbers tested 2013 0 0 0 1 0 0 0 2 2 5 8 5 9 10 29 19 16 16 24 13 9 10 3 3 2 0 0 0 0 0 0 0
Percentage positive 2013 0 0 0 0 0 0 0 0 0 20 0 0 56 20 45 47 38 38 75 69 67 60 67 0 50 0 0 0 0 0 0 0
Percentage positive 2012 0 0 0 0 0 0 0 0 0 0 33 67 33 67 33 50 67 64 67 33 67 67 55 0 0 0 0 0 0 0 0 0
Percentage positive 2003 0 0 1 0 1 1 1 1 1 3 3 6 7 10 17 21 38 35 43 46 45 45 58 29 20 15 8 0 0 0 0 0
Table 6 - Footnote *

Data became available during Week 30; this is a cumulative number of dead birds tested from Week 1 to Week 30.

Return to table 6 - footnote * referrer

Eastern Equine Encephalitis in Canada

Domestic Animals: The Canadian Food Inspection Agency reported a total of 28 cases of Eastern Equine Encephalitis in Canada: Nova Scotia (1), Ontario (25) and Quebec (2).

Of these, 27 cases (96.4%) were reported in horses and one (3.6%) case was reported in an emu in Ontario.

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