West Nile virus and other mosquito-borne diseases national surveillance report — July 30 to August 5, 2017 (Week 31)

Alternative Formats

West Nile virus

Canada

Humans

During week 31, July 30 to August 5, 2017, the Public Health Agency of Canada (PHAC) was officially informed of three additional human clinical cases of West Nile virus (WNv). This brings the total confirmed WNv cases to six since the beginning of the 2017 season. All were unclassified, and reported by the province of Ontario. One of the cases was travel-related.

Mosquitoes

As of initial surveillance, 8,653 mosquito pools have been tested for WNv in Canada: Québec (588), Ontario (7,385), Manitoba (486), and Saskatchewan (194).

A total of 155 positive pools of WNv have been found in the following four provinces:

  • 113 in Ontario [Brant County (1), Chatham-Kent (3), Durham Region (2), Eastern Ontario (2), Halton Region (10), Hamilton (4), Haliburton-Kwartha-Pine Ridge District (1), Hastings and Prince Edward Countries (5), Lambton (1), Middlesex-London (3), Niagara Region (2), Ottawa (7), Peel (22), Perth District (1), Peterborough (1), Renfrew County and District (2), Simcoe Muskoka District (1), Toronto (24), Wellington-Dufferin-Guelph (2), Windsor-Essex County (16), and York Regional (3)];
  • Thirty in Manitoba [(Winnipeg (10), Southern (3), Interlake Eastern (5), and Prairie Mountain (12)];
  • Nine in Québec [Montérégie (6), Laval (1), and  Mauricie-centre-du-Québec(2)]; and
  • Three in Saskatchewan.

Birds

As of week 31, the Canadian Wildlife Health Cooperative has tested fifty-nine dead birds for WNv [Quebec (31), Ontario (23), Saskatchewan (1), Manitoba (2) and British Columbia (2)]. Of these, forty were positive: Twenty-five in Quebec [Drummondville (1), Lachine (1), Lac-Supérieur (1), Mascouche (2), Montréal (1), Mont-Royal (1), Repentigny (1), Rivière-Rouge (2), Saint-Ambroise (1), Saint-Côme (1), Sainte-Madeleine (1), Sainte-Mélanie (1), Saint-Félix-de-Valois (1), Saint-Hippolyte (1), Saint-Hyacinthe (1), Saint-Jean-de-Matha (1), Saint-Jérôme (1), Saint-Lambert (2), Saint-Ours (1), Sherbrooke (1), Terrebonne (1), and Trois-Rivières (1)]; two in Manitoba [Winnipeg (2)]; and thirteen in Ontario [Campbellsville (6), Dryden (1), Guelph (1), Pickerel (1), Sarnia (1), Sudbury (1), and Thunder Bay (2)].

Domestic Animals

The Canadian Food Inspection Agency has not reported any domestic animals tested positive for WNv since the beginning of the 2017 season.

United States and U.S. territories

As of August 8, 2017, 159 human cases of WNv have been reported by the Centers for Disease Control and Prevention (CDC). Of these, ninety-one (57%) were classified as neuroinvasive disease and sixty-eight (43%) as non-neuroinvasive disease. In addition, forty presumptive viremic blood donors have been identified.

Detailed information can be accessed via the CDC web site.

Europe and Neighbouring Countries

As of August 4, 2017, the European Centre for Disease Prevention and Control (ECDC) reported ten human cases (confirmed and probable) of West Nile fever [Greece (5), Italy (1) and Israel ( 4)]

Detailed information can be accessed via the ECDC web site.

Other Mosquito-borne Diseases

Canada

Eastern Equine Encephalitis virus:

No human cases of eastern equine encephalitis virus have been reported to the Public Health Agency of Canada in 2017.

California Serogroup virus:

Since January 1, 2017, nine human cases of laboratory-confirmed cases/exposures of California serogroup virus were diagnosed by the National Microbiology Laboratory in Canada: Alberta (2), Saskatchewan (1), and Quebec (6).  Of these cases, four cases were further classified as Jamestown Canyon virus.

Figure 1: Geographic distribution of West Nile virus human clinical cases in Canada, as of August 5, 2017

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Figure 1: Text Equivalent

Map showing geographic distribution of human clinical cases of WNV in Canada.

As of surveillance week 31, ending August 5, 2017, there are six human clinical cases of WNV in Canada; all from Ontario.

Figure 2: West Nile virus human clinical cases and asymptomatic infections by province/ territory and by report week, as of August 5, 2017

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*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.

Figure 2: Text Equivalent

As of week 31, ending August 5, 2017, there are three West Nile virus human clinical cases in Canada.

Table showing human clinical cases and asymptomatic infections associated with WNV in Canada, by province or territory and by week monitoring, dated 5 August 2017
  Report Week, 2017
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 49 50 Total
Newfoundland and Labrador 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
New Brunswick 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
Québec 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0                                       0
Ontario 0 0 0 0 0 0 0 0 0 0 0 0 2 1 3                                       6
Manitoba 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                                       0
Alberta 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
Yukon 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0                                       0
Northwest Territories 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
Total 0 0 0 0 0 0 0 0 0 0 0 0 2 1 3                                       6
Figure 3: West Nile virus human clinical cases and asymptomatic infections by report week for selected years, in Canada

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Figure 3: Text Equivalent
Table showing WNV Human Clinical cases and Asymptomatic Infections in Canada, 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 48 49 50 Total
2017 0 0 0 0 0 0 0 0 0 0 0 0 2 1 3                                       6
2016 0 0 0 1 0 0 0 1 0 0 0 0 0 1 5 5 14 11 16 12 9 6 15 5 0 0 3 1 0 1 0 0 0 0 106
2014 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 4 3 5 6 1 1 0 0 1 0 0 0 0 0 0 0 0 0 22
2012 0 0 0 0 0 0 1 0 0 0 3 5 11 16 27 53 63 57 43 43 45 24 30 14 9 5 1 0 0 0 0 0 0 0 450
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 0 0 0 2378
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 0 0 0 1450
Table 1: West Nile virus human clinical cases and asymptomatic infections by province/territory for the current report week and year to date, 2017 season
  Week 31: July 30 to August 5, 2017
West Nile virus neurological syndrome West Nile virus non-neurological syndrome Unclassified/
unspecified
Total clinical casesTable 1 Footnote 1 Number of travel-related casesTable 1 Footnote 2 West Nile virus asymptomatic infectionTable 1 Footnote 3

Table 1 Footnotes

Table 1 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 1 footnote 1 referrer

Table 1 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 1 footnote 2 referrer

Table 1 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 1 footnote 3 referrer

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 0 0 0 0 0 0
Ontario 0 0 3 3 0 0
Manitoba 0 0 0 0 0 0
Saskatchewan - 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 0 0 3 3 0 0
Year to date: January 1 to August 5, 2017
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 0 0 0 0 0 0
Ontario 0 0 6 6 1 0
Manitoba 0 0 0 0 0 0
Saskatchewan - 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 0 0 6 6 1 0
Table 2: Number of mosquito pools tested for West Nile virus and number of positive mosquito pools by province/territory, 2017 season
Province Year to date: January 1 to August 5, 2017  
Number of positive mosquito pools Number of mosquito pools tested Percentage of positive mosquito pools (%)
Quebec 9 588 1.53
Ontario 113 7385 1.53
Manitoba 30 664 4.51
Saskatchewan 3 247 1.21
Alberta - - -
British Columbia - - -
Newfoundland and Labrador - - -
Prince Edward Island - - -
Nova Scotia - - -
New Brunswick - - -
Yukon Territory - - -
Northwest Territory - - -
Nunavut - - -
Total 155 8884 1.74
Table 3: Total number of WNV mosquito pools tested by report week and by province/ territory, 2017 seasonTable 3 Footnote 1
Province / Territory Report week 33, 2017
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

Table 3 Footnotes

Table 3 Footnote 1

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

Return to table 3 footnote 1 referrer

Newfoundland and Labrador 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                  
New Brunswick 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                  
Quebec 0 0 0 0 0 0 0 0 147 147 147 147 0                  
Ontario 13 15 43 84 194 299 718 794 964 1003 1037 1053 1168                  
Manitoba 0 0 0 0 15 45 48 16 60 93 96 113 178                  
Saskatchewan 0 0 0 0 6 20 11 18 25 31 38 45 53                  
Alberta 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                  
Yukon Territory 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                  
Nunavut 0 0 0 0 0 0 0 0 0 0 0 0 0                  
Total 13 15 43 84 215 364 777 828 1196 1274 1318 1358 1399                  
Figure 4: Reported number of dead birds tested positive for West Nile virus by province/ territory and by report week, 2017 season in Canada

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Figure 4: Text Equivalent

As of week 31, ending August 5 in 2017, there are 15 West Nile virus cases in birds, in Canada.

Table showing the Reported number of dead birds tested positive for WNV in Canada, by Province/ Territory and by Report week, 2017 season
  Report Weeks of 2017
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 49 50 Total
Newfoundland and Labrador 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
New Brunswick 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
Quebec 0 0 0 0 0 0 0 0 0 0 0 3 3 9 10 25
Ontario 0 0 0 0 0 0 0 0 3 1 1 0 0 2 5 12
Manitoba 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 2
Saskatchewan 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
British Columbia 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
Northwest Territory 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
Total 0 0 0 0 0 0 0 0 3 1 1 3 3 13 15 39
Figure 5: Percentage of dead birds tested positive for West Nile virus by report week in 2012, 2015, 2016, 2017 and number of dead birds tested positive, by report week, 2017, in CanadaFigure 5 Footnote 2

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Figure 5 Footnote 2

Not all provinces are conducting dead bird surveillance as part of their own WNV surveillance program. However, WNV positive dead birds may be identified through the National Wildlife Disease Surveillance Program of the Canadian Wildlife Health Cooperative.

Return to figure 5 footnote 2 referrer

Figure 5: Text Equivalent
Table showing Percentage of dead birds tested positive for WNV in Canada, by Report week in 2012, 2015, 2016 and 2017 and number of dead birds tested positive for WNV, by Report week, 2017 season
  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 48 49 50
% 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 0 0
% 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 0 0
% positive 2015 0 0 0 0 0 0 0 100 0 0 0 100 83 60 73 0 25 67 83 57 50 80 67 0 21 0 0 0 0 50 0 0 0 0
% positive 2016 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 33 50 23 25 80 43 43 20 36 0 0 0 0 0 0 0 0 0 0
% positive 2017 0 0 0 0 0 0 0 0 100 33 50 100 33 87 83                                      
# positive 2017 0 0 0 0 0 0 0 0 3 1 1 3 3 13 15                                      
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