West Nile virus and other mosquito-borne diseases national surveillance report - August 13 to August 19, 2017 (Week 33)

Alternative Formats

West Nile Virus

Canada

Humans

During week 33, August 13 to August 19, 2017, Ontario reported one additional clinical case of West Nile virus (WNv). Ontario also reported an additional five cases with episode dates dating back to week 28.

As of week 33, fifteen cases (ON=14, BC=1) have been reported to the Public Health Agency of Canada (PHAC). Of the fourteen cases in Ontario, there are twelve clinical cases (confirmed or probable) and two asymptomatic infections. Four cases in Ontario are travel-related. The one case in British Columbia was reported as an asymptomatic infection.

Mosquitoes

As of initial surveillance, 11,470 mosquito pools have been tested for WNv in Canada: Québec (735), Ontario (9,516), Manitoba (872), and Saskatchewan (347).

A total of 322 positive pools of WNv have been found in the following four provinces: 264 in Ontario [Brant County (2), Chatham-Kent (3), Durham Region (7), Eastern Ontario (3), Halton Region (24), Hamilton (19), Haliburton-Kwartha-Pine Ridge District (1), Hastings and Prince Edward Countries (9), Huron County (2), Kingston-Frontenac and Lennox and Addington (2), Lambton (1), Middlesex-London (4), Niagara Region (8), Northwestern (1), Ottawa (15), Oxford County (1), Peel (62), Perth District (5), Peterborough County-City (1), Renfrew County and District (2), Simcoe Muskoka District (1), Toronto (48), Waterloo (3), Wellington-Dufferin-Guelph (2), Windsor-Essex County (25), and York Regional (13)]; Thirty-seven in Manitoba [(Winnipeg (12), Southern (4), Interlake Eastern (7), and Prairie Mountain (14)]; Thirteen in Québec [Capitale-Nationale (1), Montérégie (7), Montréal (3), and Outaouais (2)]; and Eight in Saskatchewan.

Birds

As of week 33, the Canadian Wildlife Health Cooperative has tested eighty-four dead birds for WNv [Quebec (49), Ontario (26), Saskatchewan (5), Manitoba (2) and British Columbia (2)]. Of these, fifty-eight were positive: thirty-eight in Quebec [Chambly (1), Drummondville (1), Lachine (1), Lac-Supérieur (1), Laval (1), L'Avenir (1), Mascouche (2), Montréal (3), Mont Royal (1), Pointe-Claire (1), Repentigny (1), Rigaud (1), Rivière-Rouge (2), Rosemère (1), Saint-Ambroise (1), Saint-Colomban (1), Saint-Côme (2), Sainte-Madeleine (1), Sainte-Mélanie (1), Saint-Félix-de-Valois (1), Saint-Hippolyte (1), Saint-Hyacinthe (1), Saint Jean-de-Martha (1), Saint-Jean-des-Piles (1), Saint-Jérôme (1), Saint-Lambert (2), Saint-Ours (1), Sherbrooke (1), Terrebonne (1), Trois-Rivières (1), Victoriaville (1), Unknown (1)]; two in Manitoba [Winnipeg (2)]; fifteen in Ontario [Campbellville (6), Dryden (1), Guelph (1), Kingston (1), Oro-Medonte (1), Pickerel (1), Sarnia (1), Sudbury (1), Thunder Bay (2)]; and three in Saskatchewan [Saskatoon (3)].

Domestic Animals

As of week 33, two horses with WNv infection were reported to the Canadian Food Inspection Agency (CFIA): one in Alberta and the other in Saskatchewan. Also one pheasant with WNv infection located in Québec was reported to the CFIA.

United States and U.S. territories

As of August 22, 2017, 314 human cases of WNv have been reported by the Centers for Disease Control and Prevention (CDC). Of these, 190 (61%) were classified as neuroinvasive disease and 124 (39%) as non-neuroinvasive disease. In addition, seventy-one presumptive viremic blood donors have been identified.

Detailed information can be accessed via the CDC web site.

Europe and Neighbouring Countries

As of August 24, 2017, the European Centre for Disease Prevention and Control (ECDC) reported a total of sixty (confirmed and probable) cases of West Nile fever [Austria (4), Greece (37), Hungary (2), Israel (4), Italy (3), Romania (6), and Serbia (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, fifteen human cases of laboratory-confirmed cases/exposures of California serogroup virus were diagnosed by the National Microbiology Laboratory in Canada: Alberta (2), Saskatchewan (2), Manitoba (1), Ontario (1), Quebec (8), and Nova Scotia (1). Of these cases, eleven cases were further classified as Jamestown Canyon virus and one Snowshoe hare virus.

Figure 1: Geographic distribution of WNv human cases in Canada, as of August 19, 2017

Figure 1 text equivalent

Map showing geographic distribution of human cases of WNv in Canada.

As of surveillance week 33, ending August 19, 2017, there are fifteen human cases of WNv in Canada; fourteen from Ontario and one from British Columbia.

Figure 2: West Nile virus human clinical cases and asymptomatic infections by province/territory and by report week, as of August 19, 2017

Figure 2 Footnote 1

WNv 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.

Return to figure 2 footnote * referrer

Figure 2 text equivalent

As of week 33, ending August 19, 2017, there are fifteen human clinical cases and asymptomatic infections associated with WNv in Canada.

Table showing human clinical cases and asymptomatic infections associated with WNv in Canada, by province or territory and by week monitoring, dated 19 August 2017
  Report Week Figure 2 Footnote * Total
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
British Columbia 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
Ontario 0 0 0 0 0 0 0 1 0 0 0 6 2 2 0 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 14
Total 0 0 0 0 0 0 0 1 0 0 0 6 2 2 0 3 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15

Figure 3: West Nile virus human clinical cases and asymptomatic infections by report week for selected years, in Canada

Figure 3 Footnote 1

WNv 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.

Return to figure 3 footnote * referrer

Figure 3 text equivalent
Table showing WNv human clinical cases and asymptomatic infections in Canada, by report week for selected years
  Report Week Figure 3 Footnote * Total
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
2017 0 0 0 0 0 0 0 1 0 0 0 6 2 2 0 3 1                                   15
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
Province/Territory Week 33: August 13 to August 19, 2017
WNv Cases Total clinical casesTable 1 Footnote 1 # of travel related WNv casesTable 1 Footnote 2 # of asymptomatic WNv infectionsTable 1 Footnote 3
Neurological syndrome Non-Neurological syndrome Unclassified / Unspecified
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
Québec 0 0 0 0 0 0
Ontario 0 0 1 1 0 0
Manitoba 0 0 0 0 0 0
SaskatchewanTable 1 Footnote 4 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 Territories 0 0 0 0 0 0
Nunavut 0 0 0 0 0 0
Total 0 0 1 1 0 0
Year to date: January 1 to August 19, 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
Québec 0 0 0 0 0 0
Ontario 5 2 5 12 4 2
Manitoba 0 0 0 0 0 0
SaskatchewanTable 1 Footnote 4 0 - - - - -
Alberta 0 0 0 0 0 0
British Columbia 0 0 0 0 0 1
Yukon Territory 0 0 0 0 0 0
Northwest Territories 0 0 0 0 0 0
Nunavut 0 0 0 0 0 0
Total 5 2 5 12 4 3
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

Table 1 Footnote 4

Saskatchewan provides counts of WNv neurological syndrome cases only.

Return to table 1 footnote 4 referrer

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 12, 2017
Number of positive mosquito pools Number of mosquito pools tested Percentage of positive mosquito pools (%)
Quebec 13 735 1.77
Ontario 264 9,516 2.77
Manitoba 37 872 4.24
Saskatchewan 8 347 2.31
Alberta - - -
British Columbia - - -
Newfoundland and Labrador - - -
Prince Edward Island - - -
Nova Scotia - - -
New Brunswick - - -
Yukon Territory - - -
Northwest Territory - - -
Nunavut - - -
Total 322 11,470 2.81
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 of 2017 Total
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
Québec - - - - - - - - 147 147 147 147 0 147 0               735
Ontario 13 15 43 84 194 299 718 794 964 1,003 1,037 1,053 1,168 1,015 1,116               9,516
Manitoba - - - - 15 45 48 16 60 93 96 113 178 122 86               872
Saskatchewan - - - - 6 20 11 18 25 31 38 46 61 52 39               347
Alberta - - - - - - - - - - - - - - -               0
British Columbia - - - - - - - - - - - - - - -               0
Newfoundland and Labrador - - - - - - - - - - - - - - -               0
Prince Edward Island - - - - - - - - - - - - - - -               0
Nova Scotia - - - - - - - - - - - - - - -               0
New Brunswick - - - - - - - - - - - - - - -               0
Yukon Territory - - - - - - - - - - - - - - -               0
Northwest Territories - - - - - - - - - - - - - - -               0
Nunavut - - - - - - - - - - - - - - -               0
Total 13 15 43 84 215 364 777 828 1,196 1,274 1,318 1,359 1,407 1,336 1,241 0 0 0 0 0 0 0 11,470
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

Figure 4: Reported number of dead birds tested positive for WNv by province/territory and by report week, 2017 season in CanadaFigure 4 Footnote

Figure 4 Footnote 1

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 4 footnote referrer

Text Equivalent

As of week 33, ending August 19 in 2017, there are fifty-eight WNv 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 Week
14 15 16 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
Manitoba 0 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 0 0 0 0 2
Ontario 0 0 1 0 0 0 0 0 0 0 0 3 1 1 0 0 2 5 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15
Québec 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 3 9 10 7 6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 38
Saskatchewan 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3
Total 0 0 1 0 0 0 0 0 0 0 0 3 1 1 3 3 13 16 8 9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 58

Figure 5: Percentage of dead birds tested positive for WNv by report week in 2012, 2015, 2016, 2017 and number of dead birds tested positive, by report week, 2017, in CanadaFigure 5 Footnote

Figure 5 Footnote 1

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 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 the number of dead birds that tested positive for WNv by report week, 2017 season
  Report Weeks Total
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
2013 Percentage positive 0 0 0 0 0 0 0 0 0 20 0 0 56 20 45 47 38 38 75 69 67 60 67 0 50 100 0 17 0 0 0 0 0 43.1%
2014 Percentage positive 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 0 20.4%
2015 Percentage positive 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 51.0%
2016 Percentage positive 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 80 0 0 0 0 0 0 0 26.2%
2017 Percentage positive - 0 0 0 0 0 0 0 100 33 50 100 33 87 84 50 75                                  
2017 Number positive - 0 0 0 0 0 0 0 3 1 1 4 3 13 16 4 3                                  
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