West Nile Virus and Other Mosquito-Borne Disease National Surveillance Report - Aug 2 to Aug 8, 2015 (Report Week 31)

Summary

West Nile Virus in Canada

Humans: During surveillance week 31 (Aug 2 to Aug 8, 2015), one human case from Quebec was reported to the Public Health Agency of Canada.

As of surveillance week 31, a total of four human cases of West Nile virus have been reported: Ontario (2), Quebec (2). One of the cases from Quebec  was related to travel outside the province.

Mosquitoes: As of  surveillance week 31, 47 mosquito pools have tested positive for West Nile virus in Canada: Ontario (23) , Manitoba (14) , Saskatchewan (9), Quebec (1).

Dead Birds: As of surveillance week 31, the Canadian Wildlife Health Cooperative has reported 21 dead birds that tested positive for West Nile virus. Ontario (14) and Quebec (7).

Domestic Animals: As of surveillance week 31, the Canadian Food Inspection Agency reported two horses, that tested positive for West Nile virus in Canada: one from Saskatchewan and one from Ontario

West Nile Virus Human Disease Cases in the United States

As of August 4, the Centers for Disease Control and Prevention (CDC) have reported 90 human cases of West Nile virus:

Alabama (1), Arizona (17), Arkansas (1) Colorado (1), California (8), Colorado (3), Delaware (1), Florida (3), Idaho (2), Kansas (4), Louisiana (3), Maryland (1), Mississippi (3), Montana (1), Nebraska (6), New Mexico (1), North Dakota (1), Ohio (2), Oklahoma (8), Pennsylvania (1), South Dakota (5), Texas (8), Virginia (1), Washington (7) and Wyoming (1).

Of these, 50 (55.6%) were diagnosed as neuroinvasive disease cases, 40 (44.4%) as non-neuroinvasive disease cases. 3 deaths were reported. Forty one (41) presumptive viremic blood donors have been identified.

West Nile Fever in the European Union, European Economic Area and Neighbouring Countries

As of Surveillance week 31, the European Centre for Disease Prevention and Control (ECDC)   has reported two human case of West Nile fever: one in Bulgaria and one in Italy. In neighbouring countries, two cases in Israel were reported.

FIGURE 1: West Nile Virus clinical cases and asymptomatic infections, by Province/Territory and by report week, 2015 season

text description in table 1 below
TABLE 1: West Nile Virus clinical cases and asymptomatic infections, by Province/Territory and by report week, 2015 season
  Report week of 2015
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                                
Prince Edward Island 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                                
Nova Scotia 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 1 1                                
Ontario 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0                                
Manitoba 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                                
Alberta 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                                
Yukon Territory 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                                
Nunavut 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 1 0 2 1                                
TABLE 2: West Nile Virus human clinical cases and asymptomatic infections by Province/Territory for the current report week and year to date, 2015 season
  Week 31: Aug 2 to Aug 8, 2015
West Nile virus neurological syndrome West Nile virus non-neurological syndrome Unclassified/unspecified Total clinical casesTable 2 Footnote1 Number of travel-related casesTable 2 Footnote2 West Nile virus asymptomatic infectionTable 2 Footnote3

Table 2 Footnotes

Table 2 Footnote 1

Total clinical cases are  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 2 footnote 1 referrer

Table 2 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 2 footnote 2 referrer

Table 2 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 2 footnote 3 referrer

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 2 0 2 1 0
Ontario 0 0 0 0 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 2 0 2 1 0
  Year to date: January 1 to Aug 8, 2015
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 2 0 2 1 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 2 2 4 1 0

FIGURE 2: West Nile Virus clinical cases and asymptomatic infections by report week for selected years

text description in table 3 below
* 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
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

Table 3 Footnotes

Table 3 Footnote *

One of these cases was likely exposed prior to the 2014 West Nile virus season.

Return to table 3 footnote * referrer

2015 0 0 0 0 0 0 0 0 0 0 0 1 0 2 1                                
2014 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 4Table 3 Footnote * 3 5 6 1 1 0 0 1 0 0 0 0 0 0
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: Number of West Nile Virus mosquito pools tested weekly by Province/Territory - 2015 season Table 4.1 Footnote 1
  Report week of 2015
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 Total

Table 4.1 Footnotes

Table 4.1 Footnote 1

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

Return to table 4.1 footnote 1 referrer

Newfoundland and Labrador 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
New Brunswick 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
Quebec 0 0 0 0 0 0 0 0 0 120 127 132 131 129 126                           765
Ontario 0 0 0 0 0 180 356 852 886 954 1152 1216 1219 1222 1176                           9213
Manitoba 0 0 0 0 12 4 87 82 44 75 73 132 139 204 275                           1127
Saskatchewan 0 0 0 0 2 0 3 3 10 13 15 40 47 69 67                           270
Alberta 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
Yukon Territory 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
Nunavut 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0                           0
Total 0 0 0 0 14 184 446 937 940 1162 1368 1520 1536 1624 1644                           11375
TABLE 4.2: Number of mosquito pools tested and number of positive mosquito pools by Province/Territory, 2015 season
Province Year to date: January 1 to Aug 8, 2015
Number of positive mosquito pools Number of mosquito pools tested Percentage of positive mosquito pools (%)
Quebec 1 765 0.13
Ontario 23 9213 0.25
Manitoba 14 1127 1.24
Saskatchewan 9 270 3.33
Total 47 11,375 0.41

FIGURE 3: Reported number of dead birds testing positive for West Nile Virus by Province/Territory and by report week, 2015 season*

text description in table 5 below

* 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, 2015 season Table 5 Footnote *
  Report week of 2015
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

Table 5 Footnotes

Table 5 Footnote *

Data from the Canadian Wildlife Health Cooperative.

Return to table 5 footnote * referrer

Newfoundland and Labrador 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
New Brunswick 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
Quebec 0 0 0 0 0 0 0 0 0 0 0 1 1 2 3                                 7
Ontario 0 0 0 0 0 0 0 1 0 0 0 0 4 1 8                                 14
Manitoba 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                                 0
Alberta 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
Yukon Territory 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
Nunavut 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0                                 0
Total 0 0 0 0 0 0 0 1 0 0 0 1 5 3 11                                 21

FIGURE 4: Percentage of dead birds testing positive for West Nile Virus in the 2015 season by report week, as compared to the 2003, 2012 and 2014 seasons

text description in table 6 below
TABLE 6: Percentage of dead birds testing positive for West Nile Virus in the 2015 season by report week, as compared to the 2003, 2012 and 2014 seasons
  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

Table 6 Footnotes

Table 6 Footnote *

Data became available during Week 30; this is a cumulative number of dead birds tested from Week 1 to Week 30.

Return to table 6 footnote * referrer

Numbers positive 2015 0 0 0 0 0 0 0 1 0 0 0 1 5 3 11                                
Numbers tested 2015 0 0 0 0 0 0 0 1 0 0 1 1 6 5 15                                
Percentage positive 2015 0 0 0 0 0 0 0 100 0 0 0 100 83 60 73                                
Numbers positive 2014 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 2 2 4 0 2 3 0 1 0 0 0 0 0 0 0
Numbers tested 2014 0 0 0 0 0 0 0 0 0 0 0 0 0 41Table 6 Footnote * 10 13 9 7 13 6 10 3 1 4 2 1 0 0 0 0 0
Percentage positive 2014 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 15 22 29 31 0 20 100 0 25 0 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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