West Nile Virus national surveillance report: July 22 - 28, 2018

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Organization: Public Health Agency of Canada

Published: August 8, 2018

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West Nile Virus - Week 30 2018

Canada

Human

As of July 28, 2018, the Public Health Agency of Canada has been informed of four clinical (confirmed or probable) cases of West Nile virus (WNV): three in Ontario and one in Manitoba.  Of these, three (75%) have been classified as WNV neurological syndrome and one case (25%) as unspecified. No deaths have been reported.

Mosquito

To date (week 30), the PHAC has been notified of 7,179 mosquito pools tested for WNV: 416 in Saskatchewan, 1,224 in Manitoba, 4,857 in Ontario, and 682 in Québec. Of these, 118 positive mosquito pools were found: nine in Saskatchewan (Moist Mixed Grassland/Aspen Parkland [8] and Mixed Grassland [1]), eighty-one in Manitoba (Winnipeg [22], Interlake-Eastern [16], Prairie Mountain [17], and Southern [26]) and twenty-eight in Ontario (City of Ottawa [1], City of Hamilton [1], Oxford County [1], City of Toronto [1], Waterloo [2], Simcoe Muskoka District [1], Middlesex-London [1], Haldimand-Norfolk [1], Halton Region [1], Peel Region [3], Windsor-Essex County [11] and York Region [4]).

Wild Bird

As of week 30, a total of forty dead wild birds have been tested for WNV by the Canadian Wildlife Health Cooperative (CWHC) and Manitoba Agriculture: one in Alberta, seven in Saskatchewan, ten in Manitoba, fifteen in Ontario, six in Québec, and one in Nova Scotia. Of these, twenty-one dead wild birds were positive for WNV: ten  in Manitoba (Winnipeg Regional Health [10]), three in Quebec (Estrie [3]), one in Saskatchewan (Saskatoon [1]) and seven in Ontario (Wellington-Dufferin-Guelph [1], Leeds, Grenville & Lanark [1], Lambton Public Health [1], Middlesex-London [2] and Southwestern Public Health [1]) and Kingston, Frontenac, Lennox & Addington [1].

Equine

The Canadian Food Inspection Agency (CFIA) has received notification of the first confirmed case of WNV in a horse from Manitoba (Interlake-Eastern).

United States and U.S. territories

As of July 24, thirty-nine human cases of WNV have been reported to the US Centers for Disease Control and Prevention (CDC). Of these, twenty-three (59%) were classified as neuroinvasive disease and sixteen (41%) as non-neuroinvasive disease. One death has been reported. In addition, twelve presumptive viremic blood donors have been identified.

Europe and Neighboring Countries

As of July 26, ninety-seven human cases of West Nile fever have been reported to the European Centre for Disease Prevention and Control in the following countries: Serbia (41), Greece (22), Italy (24), Romania (5), and Hungary (5). Three deaths have been reported (Serbia [3]).

Weekly updates: 2018 West Nile fever transmission season

Other Mosquito-borne Diseases - Week 30 2018

Canada

Eastern Equine Encephalitis virus

No human cases of Eastern Equine Encephalitis virus (EEEV) have been reported to the PHAC, since the 2018 season.

California Serogroup virus

In surveillance week 30, no human cases/exposures of California serogroup virus were diagnosed by the National Microbiology Laboratory in the Public Health Agency of Canada.

Figure 1: Geographic distribution of WNV human clinical cases and asymptomatic infections in Canada, 2018
Figure 1. Text version below.
Figure 1 - Text description

Map showing geographic distribution of human cases of West Nile virus (WNV) in Canada.

As of July 28, 2018, three human cases associated with WNV in Canada have been reported to the Public Health Agency of Canada (PHAC).

Figure 2: WNV human clinical cases and asymptomatic infections in Canada by reported week, 2018
Figure 2. Text version below.

Figure 2 note ±: 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.

Figure 2 - Text description

As of week 30, ending July 28, 2018, there are three 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 July 28, 2018
Province / Territory Report Weekfigure 2 table note ± Total
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
British Columbia 0 0 0 0 0 0 0 0 - - - - - - - - - - - - - - - - - 0
Alberta 0 0 0 0 0 0 0 0 - - - - - - - - - - - - - - - - - 0
Manitoba 0 0 0 0 0 0 0 1 - - - - - - - - - - - - - - - - - 1
Ontario 0 0 0 0 0 1 1 0 - - - - - - - - - - - - - - - - - 2
Québec 0 0 0 0 0 0 0 0 - - - - - - - - - - - - - - - - - 0
Total 0 0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3

'-' = Not available.

Figure 2 table note ±

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 table note ± referrer

Figure 3: WNV human clinical cases and asymptomatic infections for selected years by reported week, in Canada
Figure 3. Text version below.

Figure 3 note *: 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.

Figure 3 - Text description
Table showing WNV human clinical cases and asymptomatic infections in Canada, by report week for selected years
Year Report Weekfigure 3 table note * Total
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
2018 0 0 0 0 0 1 1 1 - - - - - - - - - - - - - - - - - 3
2017 0 0 1 0 1 1 7 3 8 10 26 31 31 27 13 16 7 8 4 1 1 3 0 0 0 200
2016 0 1 0 0 0 0 0 1 5 5 14 11 16 12 9 6 15 5 0 0 3 1 0 1 0 105
2014 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 22
2012 1 0 0 0 3 5 11 16 27 53 63 57 43 43 45 24 30 14 9 5 1 0 0 0 0 450
2007 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 2,378
2003 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 1,450

'-' = Not available.

Figure 3 table note *

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 table note * referrer

Table 1: WNV human clinical cases and asymptomatic infections in Canada by reported weeks and year to date, 2018
Province/Territory Clinical Cases Total clinical casestable 1 note 1 Total travel-related casestable 1 note 2 Total asymptomatic infectionstable 1 note 3
Neurological syndrome Non-neurological syndrome Unclassified/ Unspecified
Week 30: July 22 to July 28, 2018
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 0 0 1 0 0
Manitoba 1 0 0 1 0 0
Saskatchewantable 1 note 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 Territory 0 0 0 0 0 0
Nunavut 0 0 0 0 0 0
Total 1 0 1 2 1 0
Year to date: January 1 to July 28, 2018
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 2 0 1 3 1 0
Manitoba 1 0 0 1 0 0
Saskatchewantable 1 note 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 Territory 0 0 0 0 0 0
Nunavut 0 0 0 0 0 0
Total 3 0 1 4 1 0

'-' = Not available.

Table 1 note 1

Total clinical cases are the sum of confirmed and probable: WNV neurological and non-neurological syndromes, along with any unclassified or unspecified cases.

Return to table 1 note 1 referrer

Table 1 note 2

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

Return to table 1 note 2 referrer

Table 1 note 3

Satisfies WNV 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 WNV specific nucleic acid amplification test following any positive donor screen test result.

Return to table 1 note 3 referrer

Table 1 note 4

Saskatchewan provides counts of WNV neurological syndrome cases only.

Return to table 1 note 4 referrer

Table 2: WNV mosquito surveillancetable 2 note * in Canada, as of July 28, 2018
Province / Territory Number of positive mosquito pools Number of mosquito pools tested Percentage of positive mosquito pools (%)
Saskatchewan 9 416 2.16
Manitoba 81 1,224 6.62
Ontario 28 857 0.58
Québec 0 682 0.00
Total 118 7,179 1.64
Table 2 note 1

Mosquito surveillance data is reported by the following four provinces: Quebec, Ontario, Manitoba, and Saskatchewan.

Return to table 2 note * referrer

Table 3: Total number of WNV mosquito pools tested by report week and by province/ territory, 2018table 3 note
Province Report Week Total
23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
Saskatchewan 15 18 17 45 54 79 95 93 - - - - - - - - - - 416
Manitoba 39 89 107 124 122 241 240 247 - - - - - - - - - - 1,224
Ontario - - - 842 955 1,024 963 1,073 - - - - - - - - - - 4,857
Québec 69 77 105 105 108 109 109 - - - - - - - - - - - 682
Total 123 184 229 1,116 1,131 1,453 1,407 1,413 - - - - - - - - - - 7,179

'-' = Not available.

Table 3 note 1

Detailed West Nile Virus mosquito surveillance data can be accessed through provincial/territorial websites.

Return to table 3 note referrer

Figure 4: Number of WNV positive dead wild birds in Canada by reported week, 2018figure 4 note *
Figure 4. Text version below.
Figure 4 note *

Not all provinces conduct dead wild bird surveillance as part of their respective WNV surveillance program. However, WNV positive dead wild birds may be identified through the National Wildlife Disease Surveillance Program, CWHC.

Return to figure 4 note * referrer

Figure 4 - Text description

As of week 30, ending July 28, 2018, there are twenty-one 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, 2018 season.
Province Jun Jul Aug Sept Oct Nov Total
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
Québec 0 0 0 0 0 0 0 2 1 - - - - - - - - - - - - - - - - - - 3
Ontario 0 0 0 0 0 1 0 5 1 - - - - - - - - - - - - - - - - - - 7
Manitoba 0 0 3 0 0 0 0 0 7 - - - - - - - - - - - - - - - - - - 10
Saskatchewan 0 0 0 0 0 0 0 0 1 - - - - - - - - - - - - - - - - - - 1
Total 0 0 3 0 0 0 0 7 10 - - - - - - - - - - - - - - - - - - 21

'-' = Not available.

Figure 5: Percentage of dead wild birds positive for WNV by report week in 2012, 2015, 2016, 2017, 2018 and number of dead birds positive in Canada by report week, 2018figure 5 note *
Figure 5. Text version below.
Figure 5 note *

Not all provinces conduct dead wild bird surveillance as part of their respective WNV surveillance program. However, WNV positive dead wild birds may be identified through the National Wildlife Disease Surveillance Program, CWHC.

Return to figure 5 note * referrer

Figure 5 - Text description
Table showing percentage of dead wild birds positive for WNV by report week in 2012-2018 and number of dead birds positive in Canada by report week, 2018*
  Jun Jul Aug Sept Oct Nov
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
2013 Percentage positive 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
2014 Percentage positive 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
2015 Percentage positive 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
2016 Percentage positive

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

2017 Percentage positive

0

0

0

100

25

50

100

33

87

86

53

77

74

87

80

71

57

31

43

33

20

50

50

0

0

0

2018 Percentage positive

0

0

100

0

0

50 0 78 71 - - - - - - - - - - - - - - - - -
2018 Number positive

0

0

3

0

0

1 0 7 10 - - - - - - - - - - - - - - - - -

'-' = Not available.

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