West Nile Virus national surveillance report: September 9 - September 15, 2018

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Organization: Public Health Agency of Canada

Published: September 28, 2018

ISBN: 2368-2841

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West Nile Virus - Week 37 2018

Canada

Human

During surveillance week 37, ending on September 15, 2018, the Public Health Agency of Canada was informed of 5 additional West Nile virus (WNV) infections: 4 in Ontario and 1 in Québec.  A number of other possible infections remain under investigation.

As of week 37, a total of 160 clinical cases of WNV have been reported by the following four provinces: Alberta (19), Manitoba (29), Ontario (72), and Québec (40). Of these, 67 (42%) have been classified as WNV neurological syndrome, 52 (32%) as WNV non-neurological and 41 (26%) are unspecified. Six deaths have been reported.  In addition, 17 WNV asymptomatic infections have been reported: Alberta (4), Manitoba (3), Ontario (5), and Québec (5).

Mosquito

To date (week 37), the PHAC has been notified of 16,067 mosquito pools tested for WNV: Saskatchewan (761), Manitoba (1,924), Ontario (11,914), and Québec (1,468). Of these, a total of 553 (3.44%) have tested positive for WNV: 50 in Saskatchewan, 168 in Manitoba, 296 in Ontario, and 39 in Québec.

Wild Bird

To date (week 37), 86 out of 176 dead wild birds have tested positive for WNV by the Canadian Wildlife Health Cooperative (CWHC), Manitoba Agriculture and BC Ministry of Agriculture-Animal Health Centre: British Columbia (2), Saskatchewan (3), Manitoba (14), Ontario (28), and Québec (39). In addition, 12 live birds in Québec have tested positive for WNV by the University of Montréal.

Equine

The Canadian Food Inspection Agency (CFIA) has reported 98 horses with West Nile fever in the following six provinces: British Columbia (1), Alberta (58), Saskatchewan (29), Manitoba (6), Ontario (3), and Québec (1).

United States and U.S. territories

As of September 18th, 1,077 human cases of WNV have been reported to the US Centers for Disease Control and Prevention (CDC). Of these 608 (56%) were classified as neuroinvasive disease and 469 (44%) as non-neuroinvasive disease. Thirty-five deaths have been reported. In addition, 196 presumptive viremic blood donors have been identified.

Europe and Neighboring Countries

As of September 13th, 1,318 human cases of West Nile fever have been reported to the European Centre for Disease Prevention and Control. Ninety deaths have been reported. (Weekly updates: 2018 West Nile fever transmission season).

Weekly updates: 2018 West Nile fever transmission season.

Other Mosquito-borne Diseases in Canada - Week 37 2018

Eastern Equine Encephalitis virus

The CFIA has reported 11 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), Quebec (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 September 15, 2018, 177 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 37, ending September 15, 2018, there are 177 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 15, 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 5 11 6 0 0 0 - - - - - - - - - - 23
Manitoba 0 0 0 0 0 0 0 0 0 1 2 1 5 10 6 3 4 0 - - - - - - - - - - 32
Ontario 0 1 0 0 0 0 0 0 1 4 4 6 9 17 16 10 5 4 - - - - - - - - - - 77
Quebec 0 0 0 0 0 0 0 0 0 0 1 7 8 14 7 5 2 1 - - - - - - - - - - 45
Total 0 1 0 0 0 0 0 0 1 5 7 15 27 52 35 18 11 5 0 0 0 0 0 0 0 0 0 0 177

'-' = 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 0 0 0 0 0 0 1 5 7 15 27 52 35 18 11 5 - - - - - - - - - - 177
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 37: September 9 to September 15, 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 1
Ontario 0 0 3 3 0 1
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 3 3 0 2
Year to date: January 1 to September 15, 2018
British Columbia 0 0 0 0 0 0
Alberta 2 17 0 19 4 4
Saskatchewantable 1 note 4 0 - - - - -
Manitoba 3 3 23 29 0 3
Ontario 33 21 18 72 2 5
Québec 29 11 0 40 1 5
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 67 52 41 160 7 17

'-' = 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 September 18, 2018
Province / Territory Number of positive mosquito pools Number of mosquito pools tested Percentage of positive mosquito pools (%)
Saskatchewan 50 761 6.57
Manitoba 168 1,924 8.73
Ontario 296 11,914 2.48
Québec 39 1,468 2.66
Total 553 16,067 3.44

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
Saskatchewan 0 15 18 17 45 55 90 104 96 106 62 65 52 26 10 0 - - - 761
Manitoba 15 39 89 107 124 122 241 240 247 169 172 163 113 39 29 15 - - - 1,924
Ontario 0 0 0 0 842 955 1,024 963 1,073 1,059 1,156 1,124 1,133 998 920 667 - - - 11,914
Québec 0 69 77 105 105 113 109 109 110 99 123 122 102 103 122 0 - - - 1,468
Total 15 123 184 229 1,116 1,245 1,464 1,416 1,526 1,433 1,513 1,474 1,400 1,166 1,081 682 - - - 16,067

'-' = 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

Figure 4: Number of WNV positive dead wild 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 37, ending September 15, 2018, there are 86 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
British Columbia 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 - - - - - - - - - - - 2
Saskatchewan 0 0 0 0 0 0 0 0 2 0 0 0 1 0 0 0 - - - - - - - - - - - 3
Manitoba 0 0 0 0 3 0 0 0 0 7 0 3 1 0 0 0 - - - - - - - - - - - 14
Ontario 0 0 0 0 0 2 0 3 5 3 8 4 2 0 0 1 - - - - - - - - - - - 28
Québec 0 0 0 0 0 0 1 1 1 3 10 10 5 1 5 2 - - - - - - - - - - - 39
Total 0 0 0 0 3 2 1 4 8 13 18 19 9 1 5 3 - - - - - - - - - - - 86

'-' = Not available.

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