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West Nile virus and other mosquito-borne diseases national surveillance report - September 17 to September 23, 2017 (Week 38)

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West Nile Virus

Canada

Humans

During week 38, September 17 to September 23, 2017, five confirmed clinical cases of West Nile Virus (WNV) from Ontario were reported to the Public Health Agency of Canada (PHAC).  Retrospectively, thirty additional cases were reported: six in Québec, twenty in Ontario two in Manitoba and two in Alberta.

As of week 38, 138 clinical cases and six asymptomatic infections have been reported to the PHAC by five provinces (Ontario [123], Québec [12], Manitoba [3], Alberta [5], and British Columbia [1].  Of the 138 clinical cases, fifty-one (37%) were classified as WNV neurological syndrome.  As of September 23, six deaths associated with West Nile virus have been reported to the Public Health Agency of Canada during the 2017 season.

Mosquitoes

As of initial surveillance, 16,603 mosquito pools have been tested for WNV in Canada: Québec (1,727), Ontario (13,461), Manitoba (1,028), and Saskatchewan (387).

A total of 538 positive pools of WNV have been found in the following four provinces: 404 in Ontario [Brant County (2), Chatham-Kent (3), Durham Region (10), Eastern Ontario (5), Halton Region (36), Hamilton (30), Haliburton-Kwartha-Pine Ridge District (1), Hastings and Prince Edward Countries (13), Huron County (2), Kingston-Frontenac and Lennox and Addington (5), Lambton (2), Leeds, Grenville and Lanark District (1), Middlesex-London (7), Niagara Region (15), Northwestern (1), Ottawa (34), Oxford County (1), Peel (112), Perth District (6), Peterborough County-City (2), Renfrew County and District (2), Simcoe Muskoka District (2), Toronto (62), Waterloo (3), Wellington-Dufferin-Guelph (3), Windsor-Essex County (29), and York Regional (15)]; forty-one in Manitoba[(Winnipeg (13), Southern (5), Interlake Eastern (7), and Prairie Mountain (16)]; eighty-three in Québec [Capitale-Nationale (9), Mauricie et du Centre-du-Québec (6), Montréal (10), Outaouais (3), Laval (5), Lanaudière (9), Laurentides (41)]; and ten in Saskatchewan.

Birds

As of week 38, the Canadian Wildlife Health Cooperative has tested 163 dead birds for WNV [Quebec (96), Ontario (51), Saskatchewan (12), Manitoba (2) and British Columbia (2)]. Of these, 118 were positive: seventy-four in Quebec, two in Manitoba, thirty-four in Ontario, and eight in Saskatchewan.

Domestic Animals

As of week 38, thirty-four horses with WNV infection were reported to the Canadian Food Inspection Agency (CFIA): five in Québec, thirteen in Ontario, seven in Saskatchewan, five in Alberta, and four in British Columbia. 

United States and U.S. territories

As of September 26, 2017, 1,047 human cases of WNV have been reported by the Centers for Disease Control and Prevention (CDC). Of these, 658 (63%) were classified as neuroinvasive disease and 389 (37%) as non-neuroinvasive disease. In addition, 161 presumptive viremic blood donors have been identified.

Detailed information can be accessed via the CDC web site.

Europe and Neighbouring Countries

As of September 21, 2017, the European Centre for Disease Prevention and Control (ECDC) reported a total of 184 (confirmed and probable) cases of West Nile fever [Austria (2), Greece (45), Hungary (14), Israel (9), Italy (47), Romania (39), and Serbia (28)].

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 September 23, 2017

Figure 1 text equivalent

Map showing geographic distribution of human cases of WNV in Canada.
As of surveillance week 38, ending September 23, 2017, there are 144 human cases of WNV in Canada; 123 from Ontario, one from British Columbia, five from Alberta, three from Manitoba, and twelve from Québec.

Figure 2: West Nile virus human clinical cases and asymptomatic infections by province/territory and by report week, as of September 23, 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 38, ending September 23, 2017, there are 144 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 23September 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
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 1
Ontario 0 0 0 0 0 0 0 1 0 0 1 6 3 6 4 16 13 30 21 2 15 5 0 0 0 0 0 0 0 123
Alberta 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 1 1 0 0 0 0 0 0 0 0 0 0 5
Manitoba 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 0 0 0 0 0 3
Québec 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 4 1 0 1 0 0 0 0 0 0 0 0 0 12
Total 0 0 0 0 0 0 0 1 0 0 1 6 3 8 6 19 23 32 22 3 15 5 0 0 0 0 0 0 0 144

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 1 6 3 8 6 19 23 32 22 3 15 5 0 0 0 0 0 0 0 0 0 0 0 0 144
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 2,378
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 1,450
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 38 September 17 to September 23, 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 1 1 3 5 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 1 1 3 5 0 0
Year to date: January 1 to September 23, 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 9 2 0 11 0 1
Ontario 38 38 43 119 19 4
Manitoba 2 1 0 3 0 0
SaskatchewanTable 1 Footnote 4 0 - - - - -
Alberta 2 2 1 5 1 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 51 43 44 138 20 6
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 September 23, 2017
Number of positive mosquito pools Number of mosquito pools tested Percentage of positive mosquito pools (%)
Quebec 83 1,727 4.81
Ontario 404 13,461 3.00
Manitoba 41 1,028 3.99
Saskatchewan 10 387 2.58
Alberta - - -
British Columbia - - -
Newfoundland and Labrador - - -
Prince Edward Island - - -
Nova Scotia - - -
New Brunswick - - -
Yukon Territory - - -
Northwest Territory - - -
Nunavut - - -
Total 538 16,603 3.24
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 - - - - - - - - 147 147 147 147 147 147 147 146 147 147 147 111     1,727
Ontario 13 15 43 84 194 299 718 794 964 1,003 1,037 1,053 1,168 1,015 1,116 993 931 746 634 641     13,461
Manitoba - - - - 15 45 48 16 60 93 96 113 178 122 86 104 25 20 7 -     1,028
Saskatchewan - - - - 6 20 11 18 25 31 38 46 61 52 39 40 0 0 0 0     387
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 1,554 1,336 1,388 1,283 1,103 913 788 752 0 0 16,603
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

Figure 4 text equivalent

As of week 38, ending September 23 in 2017, there are 118 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 7 4 3 5 1 0 0 0 0 0 0 0 0 0 0 0 0 0 34
Québec 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5 3 9 10 7 8 10 14 6 2 0 0 0 0 0 0 0 0 0 0 0 0 0 74
Saskatchewan 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 4 2 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 8
Total 0 0 1 0 0 0 0 0 0 0 0 3 1 1 5 3 13 16 8 19 16 17 12 3 0 0 0 0 0 0 0 0 0 0 0 0 0 118

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 43.5%
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 57 76 73 89 86 75 0                        
2017 Number positive - 0 0 0 0 0 0 0 3 1 1 5 3 13 16 8 19 16 17 12 3 0                       118

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