West Nile Virus and Other Mosquito-Borne Disease National Surveillance Report - August 17 to August 23, 2014 (Report Week 34)

Summary

Canada

Humans: During surveillance week 34 (August 17 to August 23, 2014), three human cases positive for West Nile virus were reported: two in Manitoba [Prairie Mountain (1)Footnote 1 and Winnipeg (1)] and one in Ontario [Simcoe-Muskoka (1)].

Mosquitoes: Since the start of the 2014 West Nile virus season, a reported 70 mosquito pools have tested positive for West Nile virus in Canada: 19 in Manitoba [Interlake-Eastern Health Region (7), Southern Health Region (8) and Winnipeg Health Region (4)]; 13 in Ontario [Haliburton-Kawartha-Pine Ridge District (1), Halton Regional (2), Lambton (1), Middlesex-London (3), Niagara Regional (1), Peel Regional (4) and City of Toronto (1)];19 in QuebecFootnote 2 [Laval (3), Montérégie (4) and Montreal (12)] and 19 in Saskatchewan.

Dead Birds: During surveillance week 34, the Canadian Wildlife Health Cooperative tested five dead birds for West Nile virus. One dead bird tested positive for West Nile virus in Ontario.

Since the start of the 2014 West Nile virus season, the Canadian Wildlife Health Cooperative tested 75 dead birds for West Nile virus in Canada: Saskatchewan (51), Ontario (17) and Quebec (7). Of these, four (5.3%) dead birds were positive for West Nile virus: Ontario (1), Quebec (1) and Saskatchewan (2).

Domestic Animals: Since the start of the 2014 West Nile virus season, the Canadian Food Inspection Agency reported three horses tested positive for West Nile virus in Canada: Alberta (1) and Saskatchewan (2).

National West Nile Virus surveillance data and maps can be accessed via the Public Health Agency of Canada web site.

United States

Since the start of the 2014 West Nile virus season and as of August 19, 2014, 210 West Nile virus human disease cases have been reported by the Centers for Disease Control and Prevention (CDC): Arizona (14), Arkansas (1), California (57), Colorado (12), District of Columbia (1), Georgia (1), Indiana (1), Iowa (4), Kansas (1), Louisiana (34), Mississippi (9), Missouri (1), Nebraska (9), New Jersey (1), New York (1), North Dakota (3), Oklahoma (1), Pennsylvania (2), South Dakota (21), Tennessee (2), Texas (30), Washington (3) and Wisconsin (1). Of these, 113 (53.8%) were diagnosed as neuroinvasive disease cases and 97 (46.2%) as non-neuroinvasive cases. Eleven fatal cases were reported. Seventy presumptive viremic blood donors have been identified.

Detailed information can be accessed via the Centers for Disease Control and Prevention web site.

European Union, European Economic Area and Neighbouring Countries

During surveillance week 34, the European Centre for Disease Prevention and Control (ECDC) reported a West Nile virus infection had been notified by Austria and was detected through blood donation screening; Greece reported two new cases.

Since the start of the 2014 West Nile virus season, four human cases have been reported in Europe: Austria (1) and Greece (3). Twenty-seven human cases have been reported in neighbouring countries: Bosnia and Herzegovina (13), Russian Federation (7), Serbia (5) and Israel (2).

Detailed information can be accessed via the European Centre for Disease Prevention and Control web site.

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
Prince Edward Island 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
Nova Scotia 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
Ontario 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
Manitoba 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2Footnote *
Saskatchewan 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
British Columbia 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
Northwest Territory 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
Total 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3Footnote *
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 34: August 17 to August 23, 2014
West Nile virus Neurological syndrome West Nile virus Non-Neurological syndrome Unclassified/
Unspecified
Total clinical
cases Footnote 2
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 0 0 1 1 0 0
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 0
Year to date: January 1 to August 16, 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 0
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 0

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 *
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
Prince Edward Island 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
Nova Scotia 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 **
Ontario 0 0 0 0 0 0 0 0 0 0 0 0 0 2 5 9 11 13
Manitoba 0 0 0 0 0 0 0 0 0 0 0 0 0 0 7 7 14 19
Saskatchewan 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 2 9 19
Alberta 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
Yukon Territory 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
Nunavut 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
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 23, 2014
Number of mosquito
pools tested
Number of positive
mosquito pools
Percentage of positive
mosquito pools (%)
Newfoundland and Labrador 0 0 0
Prince Edward Island 0 0 0
New Brunswick 0 0 0
Nova Scotia 0 0 0
Quebec 6,986Footnote * 19Footnote * 0.3
Ontario 9,921 13 0.1
Manitoba 1,334 19 1.4
Saskatchewan 692 19 2.7
Alberta 0 0 0
British Columbia 166 0 0
Yukon Territory 0 0 0
Northwest Territory 0 0 0
Nunavut 0 0 0
Total 19,099 70 0.4

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 Table 5 - 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
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 1 0 1
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 0 0
Saskatchewan 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 2
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 2 1 1 4

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 1
Numbers tested 2014 0 0 0 0 0 0 0 0 0 0 0 0 0 39Footnote * 10 13 8 5
Percentage positive 2014 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 13 20
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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