West Nile Virus national surveillance report: July 29 - August 4, 2018

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Organization: Public Health Agency of Canada

Published: August 14, 2018

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West Nile Virus - Week 31 2018

Canada

Human

As of August 4, 2018, the Public Health Agency of Canada has been informed of five clinical (confirmed or probable) cases of West Nile virus (WNV) and one asymptomatic infection (Ontario [5] and Manitoba [1]). Of the five clinical cases, three (60%) have been classified as WNV neurological syndrome and two cases (40%) are unspecified. No deaths have been reported.

Mosquito

To date (week 31), the PHAC has been notified of 8609 mosquito pools tested for WNV (Saskatchewan [508], Manitoba [1,393], Ontario [5,916] and Quebec [792]). Of these, a total of 195 (2.27%) have tested positive for WNV: twenty-six in Saskatchewan (Moist Mixed Grassland/Aspen Parkland [23] and Mixed Grassland [3]), 102 in Manitoba (Winnipeg [31], Interlake-Eastern [18], Prairie Mountain [23], and Southern [30]), sixty-five in Ontario (City of Ottawa [1], City of Hamilton [3], Lambton County [1], Niagara County [1], Oxford County [2], City of Toronto [11], Waterloo [2], Simcoe Muskoka District [1], Middlesex-London [1], Haldimand-Norfolk [1], Halton Region [4], Peel Region [10], Hastings and Prince Edward Counties [1],Windsor-Essex County [15], Chatham-Kent [3], Brant County [1], Perth District [1], Wellington-Dufferin-Guelph [1], and York Region [5] and two in Quebec.

Wild Bird

As of week 31, a total of forty-four 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, nineteen in Ontario, six in Québec, and one in Nova Scotia. Of these, twenty-five dead wild birds were positive for WNV: ten in Manitoba (Winnipeg Regional Health [10]), three in Quebec (Estrie [3]), two in Saskatchewan (Saskatoon [2]) and ten in Ontario (Wellington-Dufferin-Guelph [1], Leeds, Grenville & Lanark [1], Lambton Public Health [1], Middlesex-London [2], City of Hamilton [2], Region of Waterloo [1]and Southwestern Public Health [1]) and Kingston, Frontenac, Lennox & Addington [1]. In addition, four live birds have been tested positive for WNV (Quebec [4]) by the University of Montréal.

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 August 7, 106 human cases of WNV have been reported to the US Centers for Disease Control and Prevention (CDC). Of these, sixty-two (58%) were classified as neuroinvasive disease and forty-four (42%) as non-neuroinvasive disease. Four deaths have been reported. In addition, forty-four presumptive viremic blood donors have been identified.

Europe and Neighboring Countries

As of August 2, 181 human cases of West Nile fever have been reported to the European Centre for Disease Prevention and Control in the following countries: Serbia (70), Greece (51), 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 31 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 31, 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 August 4, 2018, five 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 31, ending August 4, 2018, there are five 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 August 4, 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 - - - - - - - - - - - - - - - - 0
Alberta 0 0 0 0 0 0 0 0 0 - - - - - - - - - - - - - - - - 0
Manitoba 0 0 0 0 0 0 0 1 0 - - - - - - - - - - - - - - - - 1
Ontario 0 0 0 0 0 1 2 1 0 - - - - - - - - - - - - - - - - 4
Québec 0 0 0 0 0 0 0 0 0 - - - - - - - - - - - - - - - - 0
Total 0 0 0 0 0 1 2 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5

'-' = Not available.

Figure 2 table notes

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 2 2 0 - - - - - - - - - - - - - - - - 5
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 notes

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 31: July 29 to August 4, 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 0 0 1 1 1 1
Manitoba 0 0 0 0 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 0 0 1 1 1 1
Year to date: January 1 to August 4, 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 2 4 2 1
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 2 5 2 1

'-' = Not available.

Table 1 notes

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 August 4, 2018
Province / Territory Number of positive mosquito pools Number of mosquito pools tested Percentage of positive mosquito pools (%)
Saskatchewan 26 508 5.12
Manitoba 102 1,393 7.32
Ontario 65 5,916 1.10
Québec 2 792 0.25
Total 195 8,609 2.27

Table 2 notes

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
22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
Saskatchewan 0 15 18 17 45 54 79 95 93 92 - - - - - - - - - 508
Manitoba 15 39 89 107 124 122 241 240 247 169 - - - - - - - - - 1,393
Ontario 0 - - - 842 955 1,024 963 1,073 1,059 - - - - - - - - - 5,916
Québec 0 69 77 105 105 108 109 109 110 - - - - - - - - - - 792
Total 15 123 184 229 1,116 1,239 1,453 1,407 1,523 1,320 - - - - - - - - - 8,609

'-' = Not available.

Table 3 notes

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 notes

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 31, ending August 4, 2018, there are twenty-five 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 0 - - - - - - - - - - - - - - - - - 3
Ontario 0 0 0 0 0 1 0 5 1 3 - - - - - - - - - - - - - - - - - 10
Manitoba 0 0 3 0 0 0 0 0 7 0 - - - - - - - - - - - - - - - - - 10
Saskatchewan 0 0 0 0 0 0 0 0 2 0 - - - - - - - - - - - - - - - - - 2
Total 0 0 3 0 0 1 0 7 11 3 - - - - - - - - - - - - - - - - - 25

'-' = 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 notes

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 85 100 - - - - - - - - - - - - - - - -
2018 Number positive

0

0

3

0

0

1 0 7 11 3 - - - - - - - - - - - - - - - -

'-' = Not available.

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