West Nile Virus national surveillance report: November 4 - November 10, 2018

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Organization: Public Health Agency of Canada

Published: November 30, 2018

ISBN: 2368-2841

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West Nile Virus - Week 45 2018

Canada

Human

During surveillance week 45, ending on November 10, 2018, an additional 5 clinical cases of West Nile virus (WNV) were retrospectively reported to the Public Health Agency of Canada (PHAC).  A number of other possible infections remain under investigation.

As of week 45, a total of 345 clinical cases of WNV have been reported by the following four provinces: Alberta (45), Manitoba (32), Ontario (126), and Québec (142). Of these, 189 (55%) have been classified as WNV neurological syndrome, 109 (31%) as WNV non-neurological syndrome and 47 (14%) as unspecified. Twenty-six deaths have been reported.  In addition, 25 WNV asymptomatic infections have been reported: Alberta (5), Manitoba (2), Ontario (9), and Québec (9).

Mosquito

During the 2018 West Nile virus season, PHAC was notified of 17,565 mosquito pools tested for WNV: Saskatchewan (773), Manitoba (1,924), Ontario (13,099), and Québec (1,769). Of these, 571 (3%) pools have tested positive for WNV: 52 in Saskatchewan, 168 in Manitoba, 305 in Ontario, and 46 in Québec.

Bird

To date, 144 out of 295 (49%) dead wild birds have tested positive for WNV by the Canadian Wildlife Health Cooperative (CWHC), Manitoba Agriculture and British Columbia Ministry of Agriculture-Animal Health Centre: British Columbia (3), Alberta (1), Saskatchewan (4), Manitoba (36), Ontario (37), Québec (55), New Brunswick (3), Nova Scotia (1), and Prince Edward Island (3).  In addition, one captive bird has tested positive for WNV:  Nova Scotia (1).

It is the first time since 2003 that WNV activity has been detected in birds from the Maritimes (New Brunswick, Nova Scotia, and Prince Edward Island). 

Equine

To date, the Canadian Food Inspection Agency (CFIA) has reported 123 domestic horses with West Nile virus in the following five provinces: British Columbia (1), Alberta (72), Saskatchewan (32), Manitoba (5), Ontario (11), and Québec (2).

United States and U.S. territories

As of November 13, 2,323 human cases of WNV have been reported to the US Centers for Disease Control and Prevention (CDC). Of these, 1,428 (61%) were classified as neuroinvasive disease and 895 (39%) as non-neuroinvasive disease. One hundred and ten deaths have been reported. In addition, 330 presumptive viremic blood donors have been identified.

Europe and Neighboring Countries

As of November 15, 2,048 human cases of West Nile fever have been reported to the European Centre for Disease Prevention and Control. One hundred and seventy-one deaths have been reported. (Weekly updates: 2018 West Nile fever transmission season).

Other Mosquito-borne Diseases in Canada - Week 45 2018

Eastern Equine Encephalitis virus

The CFIA has reported 13 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, 23 human cases/exposures of California serogroup virus have been reported by the National Microbiology Laboratory in the following seven provinces: Alberta (1), Saskatchewan (4), Manitoba (1), Ontario (5), Québec (5), New Brunswick (5), and Nova Scotia (2). Additional work to further type these as Jamestown Canyon virus or Snowshoe hare virus is on-going.

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 November 10, 2018, 370 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 report weekFootnote ±, 2018
Figure 2. Text version below.
Footnote ±

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

Footnote *

WNV likely acquired while travelling outside of Canada.

*

Figure 2 - Text description

As of week 45, ending November 10, 2018, there are 370 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 November 10, 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 6 13 14 8 6 2 0 0 0 0 0 0 0 - - - 50
Manitoba 0 0 0 0 0 0 0 0 0 1 1 2 6 9 6 3 4 0 2 0 0 0 0 0 0 - - - 34
Ontario 0 1 0 0 0 0 0 0 1 4 4 8 12 19 21 18 17 13 5 6 4 1 1 0 0 - - - 135
Québec 0 0 0 0 0 0 0 0 0 1 3 7 14 20 22 25 29 14 7 4 1 2 0 1 0 - - - 151
Total 0 1 1 0 0 0 0 0 1 6 8 18 38 61 63 54 56 29 14 10 5 3 1 1 0 0 0 0 370

'-' = 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 report weekfigure 3 table note ±, 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 1 0 0 0 0 0 1 6 8 18 38 61 63 54 56 29 13 10 5 3 1 1 0 0 - - 370
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 report weekFootnote * 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
Report week 45: November 4 to November 10, 2018
British Columbia 0 0 0 0 0 0
Alberta 0 0 0 0 0 0
Saskatchewantable 1 note 4 0 - - - - -
Manitoba 0 0 0 0 0 0
Ontario 0 0 0 0 0 0
Québec 0 0 0 0 0 0
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
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 0 0 0 0
Year to date: January 1 to November 10, 2018
British Columbia 0 0 0 0 0 0
Alberta 7 38 0 45 7 5
Saskatchewantable 1 note 4 0 - - - - -
Manitoba 9 12 11 32 0 2
Ontario 56 34 36 126 2 9
Québec 117 25 0 142 0 9
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
Yukon Territory 0 0 0 0 0 0
Northwest Territory 0 0 0 0 0 0
Nunavut 0 0 0 0 0 0
Total 189 109 47 345 9 25

'-' = Not available.

Table 1 notes

Table 1 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 table 1 note * referrer

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 Héma-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 November 10, 2018
Province / Territory Number of positive mosquito pools Number of mosquito pools tested Percentage of positive mosquito pools (%)
Saskatchewan 52 773 6.7
Manitoba 168 1,924 8.7
Ontario 305 13,099 2.3
Québec 46 1,769 2.6
Total 571 17,565 3.3

Table 2 notes

Table 2 note *

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

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 / Territory Report Week Total
22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
SaskatchewanTable 3 footnote 1 0 15 18 17 45 55 90 104 96 106 62 72 52 31 10 0 0 0 0 773
ManitobaTable 3 footnote 2 15 39 89 107 124 122 241 240 247 169 172 163 113 39 29 15 0 0 0 1,924
OntarioTable 3 footnote 3 0 0 0 0 842 955 1,024 963 1,073 1,059 1,156 1,124 1,133 998 920 667 667 433 85 13,099
QuébecTable 3 footnote 4 0 69 77 105 105 113 109 109 110 99 123 122 102 103 122 80 85 92 0 1,769
Total 15 123 184 229 1,116 1,245 1,464 1,416 1,526 1,433 1,513 1,481 1,400 1,171 1,081 806 752 525 85 17,565

'-' = Not available.

Table 3 notes

Table 3 note ‡

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

Return to table 3 note referrer

Table 3 footnote 1

Mosquito surveillance ended at week 36.

Return to Table 3 footnote 1 referrer

Table 3 footnote 2

Mosquito surveillance ended at week 37.

Return to Table 3 footnote 2 referrer

Table 3 footnote 3

Mosquito surveillance ended at week 40.

Return to Table 3 footnote 3 referrer

Table 3 footnote 4

Mosquito surveillance ended at week 39.

Return to Table 3 footnote 4 referrer

Figure 4: Number of WNV positive dead birds in Canadafigure 4 note * by report weekfigure 4 note , 2018
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 or by specific provinces.

Return to figure 4 note * referrer

Figure 4 note ‡

WNV positive birds are grouped by report week, based on best date available. Best date could include one of the following: date found, date of death, date submitted, or date received.

Return to figure 4 note referrer

Figure 4 - Text description

As of week 45, ending November 10, 2018, there are 144 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 / Territory Report Week*
May Jun Jul Aug Sept Oct Total
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  
British Columbia 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 1 0 0 0 0 0- 0 3
Alberta 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 1
Saskatchewan 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 2 0 0 0 0 0 0 0 0 0 0 4
Manitoba 0 0 0 0 3 0 0 0 1 2 1 3 10 3 3 1 0 0 0 0 0 0 0 7 1 1 36
Nova Scotia 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 2
Ontario 0 0 0 0 0 0 0 0 2 1 3 5 3 8 5 4 0 1 1 3 0 0 0 1 0 0 37
Québec 0 0 0 0 0 0 0 0 0 1 1 1 3 14 11 5 4 6 2 6 0 1 0 0 0 0 55
New Brunswick 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 1 0 0 0 0 3
Prince Edward Island 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 0 0 0 0 0 0 3
Total 0 0 0 0 3 0 0 0 3 4 5 11 16 25 21 13 4 7 6 10 2 3 0 9 1 1 144

'-' = Not available.

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