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West Nile virus and Other Mosquito-borne Diseases National Surveillance Report – July 16 to July 22, 2017 (Week 29)

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West Nile virus

Canada

Humans

As of surveillance week 29, ending on July 22, 2017, the Public Health Agency of Canada (PHAC) has been officially informed of two human clinical cases of West Nile virus (WNV). Both were reported by the province of Ontario [Timiskaming (1) and Windsor-Essex (1)].

Mosquitoes

As of week 29, there have been 4 provinces (Ontario, Manitoba, Quebec and Saskatchewan) with reports of positive mosquito pools of West Nile Virus.

A total of 47 positive pools of WNV have been found: 33 from Ontario [Peel Regional (5), Toronto (6), Halton(5), Haliburton-Kwartha-Pine Ridge District(1), Simcoe Muskoka District (1), Windsor-Essex County (6), Eastern Ontario (1), Durham Reginal (1), Hamilton (1), Haliburton-Kawarta-Pine Ridge district (1), Hastings and Prince Edward Countries (2), and York Regional (3)];  11 from Manitoba [(Winnipeg (3), Southern (2), Interlake eastern (1), and Prairie Mountain(5)]; 2 from Quebec [Montérégie (1), Laval (1)], and 1 from Saskatchewan.

As of initial surveillance, PHAC has received 5 992 mosquito pools tested for WNV in Canada: Quebec (294), Ontario (5164), Manitoba (387), and Saskatchewan (147).

Birds

The Canadian Wildlife Health Cooperative has tested 16 dead birds for West Nile virus: six in Quebec, nine in Ontario and one in Saskatchewan. Of these, 9 were positive for WNV: 4 in Quebec [St Lambert (2), Sherbrooke (1) and Montréal (1)], and 5 in Ontario [Campbellsville (3), Trenton Lakes (1) and Guelph (1)].

Domestic Animals

The Canadian Food Inspection Agency has not reported any domestic animals tested positive for West Nile virus since the beginning of the 2017 season.

United States and U.S. territories

As of July 22, 2017, forty five (45) human cases of WNV have been reported by the Centers for Disease Control and Prevention in the United States. Of these, 26 (57.77%) were classified as neuroinvasive disease and 19 (42.22%) as non-neuroinvasive disease. In addition, 8 presumptive viremic blood donors have been identified.

Detailed information can be accessed via the CDC web site.

Europe and Neighbouring Countries

As of July 22, 2017, the European Union Member States have reported one human case of West Nile fever in Southern Greece. In the neighbouring countries, one confirmed case and three probable cases have been reported by Israel.

Detailed information can be accessed via the ECDC web site.

Other Mosquito-borne Diseases

Canada

Eastern Equine Encephalitis virus:

No human cases of eastern equine encephalitis virus have been reported to the Public Health Agency of Canada since the 2017 season.

California Serogroup virus:

Since January 1, 2017, 9 human cases of laboratory-confirmed cases/exposures of California serogroup virus were diagnosed by the National Microbiology Laboratory in Canada: Alberta (2), Saskatchewan (1), and Quebec (6). Of these cases, four were further classified as Jamestown Canyon virus and the rest as unknown.

Figure 1: Geographic distribution of West Nile virus human clinical cases in Canada, as of July 22, 2017

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Figure 1: Text Equivalent

Map showing geographic distribution of human clinical cases of WNV in Canada.

 As of surveillance week 29, ending July 22, 2017, there are two human clinical cases of WNV in Canada; both from Ontario.

FIGURE 2: West Nile virus human clinical cases and asymptomatic infections by province/ territory and by report week, as of July 22, 2017 

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*West Nile virus 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 Equivalent

As of week 29, ending July 22, 2017, there are two West Nile virus human clinical cases in Canada.

Table showing WNV Human clinical cases and Asymptomatic Infections in Canada, by Province/ Territory and by Report week, as of week 29, ending July 22, 2017 season
  Week 29:  July 9 to July 22, 2017
West Nile virus neurological syndrome West Nile virus non-neurological syndrome Unclassified/
unspecified		 Total clinical cases Number of travel-related cases West Nile virus asymptomatic infection
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
Quebec 0 0 0 0 0 0
Ontario 0 0 2 2 0 0
Manitoba 0 0 0 0 0 0
Saskatchewan 0 0 0 0 0 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

FIGURE 3: West Nile virus human clinical cases and asymptomatic infections by report week for selected years, in Canada

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Figure 3: Text Equivalent
Table showing WNV Human Clinical cases and Asymptomatic Infections in Canada, by Report week for selected years
  Report Week
17 18 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 45 46 47 48 49 50 Total
2017 0 0 0 0 0 0 0 0 0 0 0 0 2                                            
2016 0 0 0 0 0 0 0 0 0 0 0 0 0 1 5 5 14 11 16 12 9 6 15 5 0 0 3 1 0 1 0 0 0 0  
2015 0 0 0 0 0 0 0 0 0 0 0 1 1 2 1 0 2 7 4 8 9 11 4 8 11 8 4 0 1 0 0 0 0 0 82
2013 0 0 0 0 0 1 1 0 0 0 1 2 2 5 5 6 9 10 21 16 14 12 7 2 1 0 1 1 0 0 0 0 0 1 118
2012 0 0 0 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 0 0 0 450
2007 0 0 0 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 0 0 0 2378
Table 1: West Nile virus human clinical cases and asymptomatic infections by province/territory for the current report week and year to date, 2017 season
  Week 29:  July 16 to July 22, 2017
West Nile virus neurological syndrome West Nile virus non-neurological syndrome Unclassified/
unspecified		 Total clinical casestable 1 Footnote 1 Number of travel-related casestable 1 Footnote 2 West Nile virus asymptomatic infectiontable 1 Footnote 3
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
Quebec 0 0 0 0 0 0
Ontario 0 0 2 2 0 0
Manitoba 0 0 0 0 0 0
Saskatchewan 0 0 0 0 0 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 2 2 0 0
  Year to date:  January 1 to July 22, 2017
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
Quebec 0 0 0 0 0 0
Ontario 0 0 2 2 0 0
Manitoba 0 0 0 0 0 0
Saskatchewan 0 0 0 0 0 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 2 2 0 0

Table 1 Footnotes

table 1 Footnote 1

Total clinical cases is the sum of both probable and confirmed: West Nile virus neurological and non-neurological syndromes, along with any unclassified or unspecified cases.

Return to table 1 footnote 1 referrer

table 1 Footnote 2

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

Return to table 1 footnote 2 referrer

table 1 Footnote 3

Satisfies West Nile virus 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 West Nile virus specific nucleic acid amplification test following any positive donor screen test result.

Return to table 1 footnote 3 referrer
Table 2: Number of mosquito pools tested for West Nile virus and number of positive mosquito pools by province/territory, 2017 season
Province Year to date: January 1 to July 15, 2017  
Number of positive mosquito pools Number of mosquito pools tested Percentage of positive mosquito pools (%)
Quebec 2 294 0.68
Ontario 33 5164 0.64
Manitoba 11 387 2.84
Saskatchewan 1 147 0.68
Alberta - - -
British Columbia - - -
Newfoundland and Labrador - - -
Prince Edward Island - - -
Nova Scotia - - -
New Brunswick - - -
Yukon Territory - - -
Northwest Territory - - -
Nunavut - - -
Total 47 5992 0.78
Table 3: Number of West Nile virus positive mosquito pools/ total number of WNV mosquito pools tested by report week and by province/ territory,
2017 seasontable 3 Footnote 1
Province / Territory Report week 29 of 2017
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
Newfoundland and Labrador 0 0 0 0 0 0 0 0 0 0 0                      
Prince Edward Island 0 0 0 0 0 0 0 0 0 0 0                      
New Brunswick 0 0 0 0 0 0 0 0 0 0 0                      
Nova Scotia 0 0 0 0 0 0 0 0 0 0 0                      
Quebec 0 0 0 0 0 0 0 0 147 n/a 147                      
Ontario 13 15 43 84 194 299 718 794 964 1003 1037                      
Manitoba 0 0 0 0 15 45 48 16 74 93 96                      
Saskatchewan 0 0 0 0 6 20 11 18 25 30 147                      
Alberta 0 0 0 0 0 0 0 0 0 0 0                      
British Columbia 0 0 0 0 0 0 0 0 0 0 0                      
Yukon Territory 0 0 0 0 0 0 0 0 0 0 0                      
Northwest Territory 0 0 0 0 0 0 0 0 0 0 0                      
Nunavut 0 0 0 0 0 0 0 0 0 0 0                      
Total 13 15 43 87 215 364 777 828 1210 1126 1317                      

table 3 Footnotes

table 3 Footnote 1

Detailed West Nile virus mosquito surveillance data can be accessed through Provincial/ Territorial websites

Return to table 3 footnote 1 referrer

Figure 4: Reported number of dead birds tested positive for West Nile virus by province/ territory and by report week, 2017 season in Canada 

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Figure 4: Text Equivalent

As of week 29, ending July 22 in 2017, there are 9 West Nile virus 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, 2017 season
  Report Weeks of 2017
17 18 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 45 46 47 48 49 50 Total
Newfoundland and Labrador 0 0 0 0 0 0 0 0 0 0 0 0 0                                           0
Prince Edward Island 0 0 0 0 0 0 0 0 0 0 0 0 0                                           0
New Brunswick 0 0 0 0 0 0 0 0 0 0 0 0 0                                           0
Nova Scotia 0 0 0 0 0 0 0 0 0 0 0 0 0                                           0
Quebec 0 0 0 0 0 0 0 0 0 0 0 3 1                                           4
Ontario 0 0 0 0 0 0 0 0 3 1 1 0 0                                           5
Manitoba 0 0 0 0 0 0 0 0 0 0 0 0 0                                           0
Saskatchewan 0 0 0 0 0 0 0 0 0 0 0 0 0                                           0
Alberta 0 0 0 0 0 0 0 0 0 0 0 0 0                                           0
British Columbia 0 0 0 0 0 0 0 0 0 0 0 0 0                                           0
Yukon Territory 0 0 0 0 0 0 0 0 0 0 0 0 0                                           0
Northwest Territory 0 0 0 0 0 0 0 0 0 0 0 0 0                                           0
Nunavut 0 0 0 0 0 0 0 0 0 0 0 0 0                                           0
Total 0 0 0 0 0 0 0 0 3 1 1 3 1                                           9

Figure 5: Percentage of dead birds tested positive for West Nile virus by report week in 2012, 2015, 2016, 2017 and number of dead birds tested positive, by report week, 2017, in CanadaFigure 5 Footnote 2

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Figure 5 Footnote 2

Not all provinces are conducting dead bird surveillance as part of their own WNV surveillance program. However, WNV positive dead birds may be identified through the National Wildlife Disease Surveillance Program of the Canadian Wildlife Health Cooperative.

Return to figure 5 footnote 2 referrer

Figure 5: Text Equivalent
Table showing Percentage of dead birds tested positive for WNV in Canada, by Report week in 2012, 2015, 2016 and 2017 and number of dead birds tested positive for WNV, by Report week, 2017 season
  Year 17 18 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 45 46 47 48
% Positive 2012 0 0 0 0 0 0 0 0 0 0 33 67 33 67 33 50 67 64 67 33 67 67 55 0 0 0 0 0 0 0 0 0
% Positive 2015 0 0 0 0 0 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 0
% Positive 2016 0 0 0 0 0 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 0
# Positive 2016 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 3 7 1 4 3 3 1 5 0 8 0 0 0 0 0 0
# Positive 2017 0 0 0 0 0 0 0 0 3 1 1 3 1                                      

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