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West Nile Virus and Other Mosquito-Borne Disease National Surveillance Report - August 24 to August 30, 2014 (Report Week 35)

Summary

Canada

Humans: During surveillance week 35 (August 24 to August 30, 2014), one asymptomatic infection of West Nile virus was reported in Ontario (Windsor-Essex County).

As of surveillance week 35, a reported three human clinical cases have tested positive for West Nile virus in Canada: two in Manitoba [Prairie Mountain (1)Footnote 1 and Winnipeg (1)] and one in Ontario [Simcoe-Muskoka District (1)]; these cases were clinically unclassified. One asymptomatic infection was reported in Ontario (Windsor-Essex County).

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  • Surveillance of West Nile virus

    • Mosquitoes: As of surveillance week 35, a reported 111 mosquito pools have tested positive for West Nile virus in Canada: 22 in Manitoba [Interlake-Eastern Health Region (7), Southern Health Region (11) and Winnipeg Health Region (4)]; 30 in Ontario [Haliburton-Kawartha-Pine Ridge District (1), Halton Regional (2), City of Hamilton (3), Lambton (1), Middlesex-London (4), Niagara Regional (1), City of Ottawa (1), Peel Regional (10), City of Toronto (5) and York Regional (2)]; 39 in Quebec [Laval (7), Montérégie (11) and Montreal (21)] and 20 in Saskatchewan.

    Dead Birds: During surveillance Week 35, the Canadian Wildlife Health Cooperative tested 11 dead birds for West Nile virus in Canada: Ontario (2), Quebec (3) and Saskatchewan (6). Two (18.2%) dead birds tested positive for West Nile virus in Ontario.

    As of surveillance week 35, the Canadian Wildlife Health Cooperative has tested 87 dead birds for West Nile virus in Canada: Ontario (20), Quebec (10) and Saskatchewan (57). Of these, seven (8.0%) dead birds have tested positive for West Nile virus in Canada: Ontario (4), Quebec (1) and Saskatchewan (2).

    Domestic Animals: As of surveillance week 35, the Canadian Food Inspection Agency reported five horses tested positive for West Nile virus in Canada: Alberta (3) and Saskatchewan (2).

    United States

    As of August 26, 2014, the Centers for Disease Control and Prevention (CDC) reported 297 West Nile virus human disease cases: Arizona (16), Arkansas (2), California (93), Colorado (19), District of Columbia (1), Georgia (3), Idaho (4), Illinois (1), Indiana (2), Iowa (5), Kansas (1), Louisiana (43), Massachusetts (1), Minnesota (3), Mississippi (14), Missouri (1), Montana (1), Nebraska (13), New Jersey (2), New York (2), North Dakota (3), Ohio (2), Oklahoma (2), Pennsylvania (2), South Dakota (22), Tennessee (2), Texas (30), Washington (3), Wisconsin (2) and Wyoming (2). Of these, 157 (52.9%) were diagnosed as neuroinvasive disease cases and 140 (47.1%) as non-neuroinvasive cases. Twelve fatal cases were reported. Eighty-seven presumptive viremic blood donors have been identified.

    European Union, European Economic Area and Neighbouring Countries

    As of August 28, 2014, the European Centre for Disease Prevention and Control (ECDC) reported that Greece reported three new probable cases; Italy reported its first case for the season and Romania reported its first two cases for the season. In the neighboring countries, Serbia reported nine new cases.

    Since the start of the 2014 West Nile virus season, 10 human cases have been reported in Europe: Austria (1), Greece (6), Italy (1) and Romania (2). Thirty-six human cases have been reported in neighbouring countries: Bosnia and Herzegovina (13), Russian Federation (7), Serbia (14) and Israel (2).

    Figure 1. West Nile Virus clinical cases and asymptomatic infections, by Province/Territory and by report week, 2014 season

    * 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.

    Table 1: West Nile Virus clinical cases and asymptomatic infections, by Province/Territory and by report week, 2014 season
    Provinces and
    Territories    		 Report week of 2014
    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
    Newfoundland and Labrador 0 0 0 0 0 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 0 0 0 0 0                        
    New Brunswick 0 0 0 0 0 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 0 0 0 0 0                        
    Quebec 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0                        
    Ontario 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1                        
    Manitoba 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2Footnote * 0                        
    Saskatchewan 0 0 0 0 0 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 0 0 0 0 0                        
    British Columbia 0 0 0 0 0 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 0 0 0 0 0                        
    Northwest Territory 0 0 0 0 0 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 0 0 0 0 0                        
    Total 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3Footnote * 1                        
    Table 2. West Nile Virus human clinical cases and asymptomatic infections by Province/Territory for the current Report week and year to date, 2014 Season
    Provinces and Territories Week 35: August 24 to August 30, 2014
    West Nile virus Neurological syndrome West Nile virus Non-Neurological syndrome Unclassified/
    Unspecified    		 Total clinical
    cases Table 2 - Footnote 1    		 Number of travel
    related cases Table 2 - Footnote 2    		 West Nile virus
    asymptomatic infectionsFootnote 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 0 0 0 1
    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 0 0 0 1
      Year to date: January 1 to August 30, 2014
    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 1 1 0 1
    Manitoba 0 0 2Footnote * 2Footnote * 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 3Footnote * 3Footnote * 0 1

    Figure 2. West Nile Virus clinical cases and asymptomatic infections by report week for selected years

    * 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.

    Table 3: West Nile Virus clinical cases and asymptomatic infections by report week for selected years
    Years Report week of 2014
    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
    2014 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3Footnote * 1                        
    2013 1 0 0 0 0 1 1 0 0 0 1 2 1 5 5 8 17 11 13 13 11 9 1 6 1 0 4 1 0 1 0
    2012 1 0 0 0 0 0 0 0 0 0 3 5 11 16 27 53 63 57 43 43 45 24 30 14 9 5 1 0 0 0 0
    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
    2005 0 0 0 0 0 0 0 0 0 0 0 0 0 0 4 4 11 28 28 38 45 27 15 7 12 3 3 1 0 0 0
    2003 0 0 0 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
    Table 4.1: Reported cumulative number of West Nile Virus positive mosquito pools by Province/Territory and by report week, 2014 season Footnote *
    Provinces and
    Territories    		 Report week of 2014
    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
    Newfoundland and Labrador 0 0 0 0 0 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 0 0 0 0 0                        
    New Brunswick 0 0 0 0 0 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 0 0 0 0 0                        
    Quebec 0 0 0 0 0 0 0 0 0 0 0 0 1 4 9 10 19 19Footnote ** 39                        
    Ontario 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 9 11 13 30                        
    Manitoba 0 0 0 0 0 0 0 0 0 0 0 0 0 0 7 7 14 19 22                        
    Saskatchewan 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 2 9 19 20                        
    Alberta 0 0 0 0 0 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 0 0 0 0 0                        
    Yukon Territory 0 0 0 0 0 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 0 0 0 0 0                        
    Nunavut 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0                        
    Total 0 0 0 0 0 0 0 0 0 0 0 0 1 7 22 28 53 70 111                        
    Table 4.2: Number of mosquito pools tested and number of positive mosquito pools by Province/Territory, 2014 season
    Provinces and
    Territories    		 Year to date: January 1 to August 30, 2014
    Number of mosquito
    pools tested    		 Number of positive
    mosquito pools    		 Percentage of positive
    mosquito pools (%)
    Quebec 7,974 39 0.5
    Ontario 11,019 30 0.3
    Manitoba 1,433 22 1.5
    Saskatchewan 768 20 2.6
    British Columbia 166 0 0
    Total 21,360 111 0.5

    Figure 3. Reported number of dead birds testing positive for West Nile Virus by Province/Territory and by report week, 2014 season*

    * Data from the Canadian Wildlife Health Cooperative

    Table 5: Reported number of dead birds testing positive for West Nile Virus by Province/Territory and by report week, 2014 season Footnote *
    Provinces and
    Territories    		 Report week of 2014
    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 Total
    Newfoundland and Labrador 0 0 0 0 0 0 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 0 0 0 0 0                         0
    New Brunswick 0 0 0 0 0 0 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 0 0 0 0 0                         0
    Quebec 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0                         1
    Ontario 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2                         4
    Manitoba 0 0 0 0 0 0 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 0 2 0 0 0                         2
    Alberta 0 0 0 0 0 0 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 0 0 0 0 0                         0
    Yukon Territory 0 0 0 0 0 0 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 0 0 0 0 0                         0
    Nunavut 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0                         0
    Total 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 1 2 2                         7

    Figure 4. Percentage of dead birds testing positive for West Nile Virus in the 2014 season by report week, as compared to the 2003, 2012 and 2013 seasons

    Table 6: Percentage of dead birds testing positive for West Nile Virus in the 2014 season by report week, as compared to the 2003, 2012 and 2013 seasons
      Report week of 2014
    17 18 19 20 21 22 23 24 26 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
    Numbers positive 2014 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 1 2 2                        
    Numbers tested 2014 0 0 0 0 0 0 0 0 0 0 0 0 0 39Footnote * 10 13 8 6 11                        
    Percentage positive 2014 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 13 33 18                        
    Numbers positive 2013 0 0 0 0 0 0 0 0 0 1 0 0 5 2 13 9 6 6 18 9 6 6 2 0 1 0 0 0 0 0 0
    Numbers tested 2013 0 0 0 1 0 0 0 2 2 5 8 5 9 10 29 19 16 16 24 13 9 10 3 3 2 0 0 0 0 0 0
    Percentage positive 2013 0 0 0 0 0 0 0 0 0 20 0 0 56 20 45 47 38 38 75 69 67 60 67 0 50 0 0 0 0 0 0
    Percentage 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
    Percentage positive 2003 0 0 1 0 1 1 1 1 1 3 3 6 7 10 17 21 38 35 43 46 45 45 58 29 20 15 8 0 0 0 0

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