West Nile Virus national surveillance report: August 26 to September 1, 2018

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Organization: Public Health Agency of Canada

Published: September 13, 2018

ISBN: 2368-2841

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West Nile Virus - Week 35 2018

Canada

Human

During surveillance week 35, ending on September 1, 2018, the Public Health Agency of Canada was informed of three additional West Nile virus (WNV) infections: one in Manitoba, and two in Ontario.

As of week 35, a total of sixty clinical cases of WNV have been reported by the following four provinces: Alberta (5), Manitoba (16), Ontario (32), and Québec (7). Of these, twenty-two (37%) have been classified as WNV neurological syndrome, eighteen (30%) as WNV non-neurological and twenty (33%) are unspecified. Three deaths have been reported. In addition, fifteen WNV asymptomatic infections have been reported: three in Alberta, seven in Manitoba, two in Ontario and three in Québec.

Mosquito

To date (week 35), the PHAC has been notified of 14,201 mosquito pools tested for WNV: Saskatchewan (751), Manitoba (1,880), Ontario (10,327) and Québec (1,243). Of these, a total of 511 (3.60%) have tested positive for WNV: forty-nine in Saskatchewan, 167 in Manitoba, 261 in Ontario, and thirty-four in Québec.

Wild Bird

To date (week 35), seventy-one out of 129 dead wild birds have tested positive for WNV by the Canadian Wildlife Health Cooperative (CWHC) and Manitoba Agriculture: three in Saskatchewan, fourteen in Manitoba, twenty-five in Ontario, and twenty-nine in Québec. In addition, four live birds in Québec have been tested positive for WNV by the University of Montréal.

Equine

The Canadian Food Inspection Agency (CFIA) has reported fifty-three horses with West Nile fever in the following five provinces: Alberta (27), Saskatchewan (18), Manitoba (6), Ontario (1), and Québec (1).

United States and U.S. territories

As of September 4th, 559 human cases of WNV have been reported to the US Centers for Disease Control and Prevention (CDC). Of these, 312 (56%) were classified as neuroinvasive disease and 247 (44%) as non-neuroinvasive disease. Eighteen deaths have been reported. In addition, 136 presumptive viremic blood donors have been identified.

Europe and Neighboring Countries

As of September 6th, 1,112 human cases of West Nile fever have been reported to the European Centre for Disease Prevention and Control. Seventy-one deaths have been reported.

Weekly updates: 2018 West Nile fever transmission season

Other Mosquito-borne Diseases in Canada - Week 35 2018

Eastern Equine Encephalitis virus

The CFIA has reported six horses testing positive for Eastern Equine Encephalitis virus (EEEV) in Ontario. No human cases of EEEV have been reported to the PHAC during the 2018 season.

California Serogroup virus

Since May 1, 2018, fifteen human cases/exposures of California serogroup virus have been reported by the National Microbiology Laboratory in the following five provinces: Alberta (1), Saskatchewan (2), Ontario (4), Quebec (7) and New Brunswick (1). Of the 15 cases, nine were further typed as Jamestown Canyon virus, and two as Snowshoe hare virus

Figure and tables

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 September 1, 2018, seventy-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 35, ending September 1, 2018, there are seventy-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 September 1, 2018
Province / Territory Report Weekfigure 2 table note ± Total
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
Alberta 0 0 0 0 0 0 0 0 0 0 0 1 1 4 2 0 - - - - - - - - - - - - 8
Manitoba 0 0 0 0 0 0 0 0 0 1 1 1 5 11 3 1 - - - - - - - - - - - - 23
Ontario 0 1 0 0 0 0 0 0 1 2 2 4 4 10 8 2 - - - - - - - - - - - - 34
Quebec 0 0 0 0 0 0 0 0 0 0 1 3 2 3 1 0 - - - - - - - - - - - - 10
Total 0 1 0 0 0 0 0 0 1 3 4 9 12 28 14 3 0 0 0 0 0 0 0 0 0 0 0 0 75

'-' = 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
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
2018 0 1 0 0 0 0 0 0 1 3 4 9 12 28 14 3 - - - - - - - - - - - - 75
2017 0 0 0 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 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 0 105
2014 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 22
2012 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 0 450
2007 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 2,378
2003 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 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 35: August 26 to September 1, 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 1 2 0 0
Manitoba 0 0 1 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 2 3 0 0
Year to date: January 1 to September 1, 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 4 2 1 7 1 3
Ontario 14 9 9 32 2 2
Manitoba 3 3 10 16 0 7
Saskatchewantable 1 note 4 0 - - - - -
Alberta 1 4 0 5 2 3
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 22 18 20 60 5 15

'-' = 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 September 1, 2018
Province / Territory Number of positive mosquito pools Number of mosquito pools tested Percentage of positive mosquito pools (%)
Saskatchewan 49 751 6.52
Manitoba 167 1,880 8.88
Ontario 261 10,327 2.53
Québec 34 1,243 2.74
Total 511 14,201 3.60

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 55 90 104 96 106 62 65 52 26 - - - - - 751
Manitoba 15 39 89 107 124 122 241 240 247 169 172 163 113 39 - - - - - 1,880
Ontario 0 0 0 0 842 955 1,024 963 1,073 1,059 1,156 1,124 1,133 998 - - - - - 10,327
Québec 0 69 77 105 105 113 109 109 110 99 123 122 102 - - - - - - 1,243
Total 15 123 184 229 1,116 1,245 1,464 1,416 1,526 1,433 1,513 1,474 1,400 1,063 - - - - - 14,201

'-' = 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 35, ending September 1, 2018, there are seventy-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 2 7 9 6 2 - - - - - - - - - - - - - 29
Ontario 0 0 0 0 0 1 0 5 1 3 5 7 3 0 - - - - - - - - - - - - - 25
Manitoba 0 0 0 0 3 0 0 0 7 0 0 3 1 0 - - - - - - - - - - - - - 14
Saskatchewan 0 0 0 0 0 0 0 0 2 0 0 0 1 0 - - - - - - - - - - - - - 3
Total 0 0 0 0 3 1 0 7 11 5 12 19 11 2 - - - - - - - - - - - - - 71

'-' = 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

0

0

60

20 0 78 79 83 75 59 39 33 - - - - - - - - - - - -
2018 Number positive

0

0

0

0

3

1 0 7 11 5 12 19 11 2 - - - - - - - - - - - -

'-' = Not available.

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