West Nile Virus and Other Mosquito-Borne Disease National Surveillance Report - August 31 to September 6, 2014 (Report Week 36)

Summary

Canada

Humans: During surveillance week 36 (August 31 to September 6, 2014), three human clinical cases of West Nile virus were reported in Ontario: Lambton (1), City of Ottawa (1) and City of Toronto (1). Of these, two (66.7%) are clinically classified as West Nile virus neurological syndrome and one (33.3%) as West Nile virus non-neurological syndrome.

As of surveillance week 36, six human clinical cases of West Nile virus have been reported in Canada: two in Manitoba [Prairie Mountain Health Region (1)Footnote 1 and Winnipeg Health Region (1)] and four in Ontario [Lambton (1), City of Ottawa (1), Simcoe-Muskoka District (1) and City of Toronto (1)]. Of these, three (50.0%) are clinically classified as West Nile virus neurological syndrome; two (33.3%) as West Nile virus non-neurological syndrome and one (16.7%) as unclassified/unspecified. In addition, one asymptomatic infection was reported in Ontario (Windsor-Essex County).

Mosquitoes: As of surveillance week 36, a reported 157 mosquito pools have tested positive for West Nile virus in Canada: 24 in Manitoba [Interlake-Eastern Health Region (7), Prairie Mountain Health Region (1), Southern Health Region (11) and Winnipeg Health Region (5)]; 43 in Ontario [Haliburton-Kawartha-Pine Ridge District (1), Halton Regional (2), City of Hamilton (7), Lambton (1), Middlesex-London (4), Niagara Regional (2), City of Ottawa (1), Peel Regional (16), City of Toronto (6), Windsor-Essex County (1) and York Regional (2)]; 70 in Quebec [Laval (7), Montérégie (26) and Montreal (37)] and 20 in Saskatchewan.

Dead Birds: As of surveillance week 36, the Canadian Wildlife Health Cooperative has tested 92 dead birds for West Nile virus in Canada: Ontario (20), Quebec (13) and Saskatchewan (59). Of these, eight (8.7%) dead birds have tested positive for West Nile virus in Canada: Ontario (4), Quebec (2) and Saskatchewan (2).

Domestic Animals: As of surveillance week 36, the Canadian Food Inspection Agency reported nine horses tested positive for West Nile virus in Canada: Alberta (5) and Saskatchewan (4).

United States

As of September 2, 2014, the Centers for Disease Control and Prevention (CDC) reported 399 West Nile virus human disease cases:

Arizona (28), Arkansas (2), California (128), Colorado (19), District of Columbia (1), Georgia (6), Idaho (11), Illinois (2), Indiana (2), Iowa (7), Kansas (2), Louisiana (43), Maryland (1), Massachusetts (1), Minnesota (4), Mississippi (15), Missouri (1), Montana (2), Nebraska (17), New Jersey (2), New York (2), North Dakota (4), Ohio (3), Oklahoma (4), Pennsylvania (2), South Dakota (26), Tennessee (3), Texas (49), Utah (1), Washington (4), Wisconsin (3) and Wyoming (4).

Of these, 214 (53.6%) were diagnosed as neuroinvasive disease cases and 185 (46.4%) as non-neuroinvasive disease cases. Sixteen fatal cases were reported. One hundred and one presumptive viremic blood donors have been identified.

European Union, European Economic Area and Neighbouring Countries

As of September 4, 2014, the European Centre for Disease Prevention and Control (ECDC) reported 10 new West Nile virus human cases in Europe: Hungary (2), Greece (5) and Romania (3). In the neighboring countries, Serbia reported 12 new cases.

As of September 4, 2014, 20 West Nile virus human cases have been reported in Europe: Austria (1), Greece (11), Hungary (2), Italy (1) and Romania (5). Forty-eight human cases have been reported in the neighbouring countries: Bosnia and Herzegovina (13), Israel, Russian Federation (7) and Serbia (26).

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 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 0 0 0 0
Ontario 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 3
Manitoba 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2Footnote * 0 0
Saskatchewan 0 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 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 0 0 3Table 1 - Footnote * 1 3
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 36: August 31 to September 6, 2014
West Nile virus Neurological syndrome West Nile virus Non-Neurological syndrome Unclassified/
Unspecified
Total clinical
casesFootnote 1
Number of travel
related casesFootnote 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 2 1 0 3 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 2 1 0 3 0 0
Year to date: January 1 to September 6, 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 2 1 1 4 0 1
Manitoba 1 1Footnote ** 0 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 3 2Footnote * 1 6Footnote * 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 3
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 seasonFootnote *
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 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 1 4 9 10 19 19Footnote ** 39 70
Ontario 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 9 11 13 30 43
Manitoba 0 0 0 0 0 0 0 0 0 0 0 0 0 0 7 7 14 19 22 24
Saskatchewan 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 2 9 19 20 20
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 1 7 22 28 53 70 111 157
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 September 6, 2014
Number of mosquito
pools tested
Number of positive
mosquito pools
Percentage of positive
mosquito pools (%)
Quebec 8,842 70 0.8
Ontario 11,887 43 0.4
Manitoba 1,489 24 1.6
Saskatchewan 813 20 2.5
British Columbia 220 0 0
Total 23,251 157 0.7

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 seasonFootnote *
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 0
Prince Edward Island 0 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 0
Nova Scotia 0 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 1 0 2
Ontario 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 0 4
Manitoba 0 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 0 2
Alberta 0 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 0
Yukon Territory 0 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 0
Nunavut 0 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 3 0 8

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 3 0
Numbers tested 2014 0 0 0 0 0 0 0 0 0 0 0 0 0 39Footnote * 10 13 8 6 12 3
Percentage positive 2014 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 13 33 25 0
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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