West Nile Virus national surveillance report: September 2 - September 8, 2018

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Organization: Public Health Agency of Canada

Published: September 20, 2018

ISBN: 2368-2841

West Nile Virus - Week 36 2018

Canada

Human

During surveillance week 36, ending on September 8, 2018, the Public Health Agency of Canada was informed of 2 additional West Nile virus (WNV) infections: 1 in Manitoba and 1 in Québec. A number of other possible infections remain under investigation.

As of week 36, a total of 107 clinical cases of WNV have been reported by the following four provinces: Alberta (8), Manitoba (25), Ontario (52), and Québec (22). Of these, 42 (39%) have been classified as WNV neurological syndrome, 33 (31%) as WNV non-neurological and 32 (30%) are unspecified. Five deaths have been reported. In addition, 12 WNV asymptomatic infections have been reported: Alberta (4), Manitoba (3), Ontario (2), and Québec (3).

Mosquito

To date (week 36), the PHAC has been notified of 15,263 mosquito pools tested for WNV: Saskatchewan (761), Manitoba (1,909), Ontario (11,247), and Québec (1,346). Of these, a total of 537 (3.52%) have tested positive for WNV: 50 in Saskatchewan, 168 in Manitoba, 283 in Ontario, and 36 in Québec.

Wild Bird

During surveillance week 36, British Columbia reported their first WNV positive dead wild bird. To date (week 36), 83 out of 171 dead wild birds have tested positive for WNV by the Canadian Wildlife Health Cooperative (CWHC), Manitoba Agriculture and BC Ministry of Agriculture-Animal Health Centre: British Columbia (2), Saskatchewan (3), Manitoba (14), Ontario (27), and Québec (37). In addition, 4 live birds in Québec have tested positive for WNV by the University of Montréal.

Equine

The Canadian Food Inspection Agency (CFIA) has reported 69 horses with West Nile fever in the following four provinces: Alberta (37), Saskatchewan (24), Manitoba (6), and Ontario (2).

United States and U.S. territories

As of September 4^th, 559 human cases of WNV have been reported to the US Centers for Disease Control and Prevention (CDC). Of these, 312 (56%) were classified as neuroinvasive disease and 247 (44%) as non-neuroinvasive disease. Eighteen deaths have been reported. In addition, 136 presumptive viremic blood donors have been identified.

Europe and Neighboring Countries

As of September 6^th, 1,112 human cases of West Nile fever have been reported to the European Centre for Disease Prevention and Control. Seventy-one deaths have been reported.

Weekly updates: 2018 West Nile fever transmission season

Other Mosquito-borne Diseases in Canada - Week 36 2018

Eastern Equine Encephalitis virus: The CFIA has reported ten horses testing positive for Eastern Equine Encephalitis virus (EEEV) in Ontario. No human cases of EEEV have been reported to the PHAC during the 2018 season.
California Serogroup virus: Since May 1, 2018, fifteen human cases/exposures of California serogroup virus have been reported by the National Microbiology Laboratory in the following seven provinces: Alberta (1), Saskatchewan (4), Manitoba (1), Ontario (5), Quebec (5), New Brunswick (5), and Nova Scotia (2). Additional work to further type these as Jamestown Canyon virus or Snowshoe hare virus is on-going.

Figure and tables

Figure 1. Text version below. — **Figure 1: Geographic distribution of WNV human clinical cases and asymptomatic infections in Canada, 2018**

Figure 2. Text version below. — **Figure 2: WNV human clinical cases and asymptomatic infections in Canada by report week^{Footnote ±}, 2018**

Table showing human clinical cases and asymptomatic infections associated with WNV in Canada, by province or territory and by week monitoring, dated September 8, 2018
Province / Territory	Report Week^{figure 2 table note ±}	Total
Alberta	0	0	0	0	0	0	0	0	0	0	0	1	2	7	2	0	0	-	-	-	-	-	-	-	-	-	-	-	12
Manitoba	0	0	0	0	0	0	0	0	0	1	2	1	5	10	6	2	1	-	-	-	-	-	-	-	-	-	-	-	28
Ontario	0	1	0	0	0	0	0	0	1	4	4	6	7	14	13	4	0	-	-	-	-	-	-	-	-	-	-	-	54
Quebec	0	0	0	0	0	0	0	0	0	0	1	4	3	11	4	1	1	-	-	-	-	-	-	-	-	-	-	-	25
Total	0	1	0	0	0	0	0	0	1	5	7	12	17	42	25	7	2	0	0	0	0	0	0	0	0	0	0	0	119
'-' = Not available. Figure 2 table notes Figure 2 table note ± WNV 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. Return to figure 2 table note ± referrer

Figure 3. Text version below. — **Figure 3: WNV human clinical cases and asymptomatic infections for selected years by report week^{figure 3 table note ±}, in Canada**

Table showing WNV human clinical cases and asymptomatic infections in Canada, by report week for selected years
Year	Report Week^{figure 3 table note ±}	Total
2018	0	1	0	0	0	0	0	0	1	5	7	12	17	42	25	7	2	-	-	-	-	-	-	-	-	-	-	-	119
2017	0	0	0	0	0	1	0	1	1	7	3	8	10	26	31	31	27	13	16	7	8	4	1	1	3	0	0	0	200
2016	0	0	0	0	1	0	0	0	0	0	1	5	5	14	11	16	12	9	6	15	5	0	0	3	1	0	1	0	105
2014	0	0	0	0	0	0	0	0	0	1	0	0	0	4	3	5	6	1	1	0	0	1	0	0	0	0	0	0	22
2012	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	450
2007	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	2,378
2003	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	1,450
'-' = Not available. Figure 3 table notes Figure 3 table note ± WNV 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. Return to figure 3 table note ± referrer

Table 1: WNV human clinical cases and asymptomatic infections in Canada by report week^{Footnote *} and year to date, 2018
Province/Territory	Clinical Cases			Total clinical cases^{table 1 note 1}	Total travel-related cases^{table 1 note 2}	Total asymptomatic infections^{table 1 note 3}
Province/Territory	Neurological syndrome	Non-neurological syndrome	Unclassified/ Unspecified	Total clinical cases^{table 1 note 1}	Total travel-related cases^{table 1 note 2}	Total asymptomatic infections^{table 1 note 3}
Report week 36: September 2 to September 8, 2018
British Columbia	0	0	0	0	0	0
Alberta	0	0	0	0	0	0
Saskatchewan^{table 1 note 4}	0	-	-	-	-	-
Manitoba	0	0	1	1	0	0
Ontario	0	0	0	0	0	0
Québec	1	0	0	1	0	0
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
Yukon Territory	0	0	0	0	0	0
Northwest Territory	0	0	0	0	0	0
Nunavut	0	0	0	0	0	0
Total	1	0	1	2	0	0
Year to date: January 1 to September 8, 2018
British Columbia	0	0	0	0	0	0
Alberta	1	7	0	8	2	4
Saskatchewan^{table 1 note 4}	0	-	-	-	-	-
Manitoba	3	3	19	25	0	3
Ontario	22	18	12	52	2	2
Québec	16	5	1	22	1	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
Yukon Territory	0	0	0	0	0	0
Northwest Territory	0	0	0	0	0	0
Nunavut	0	0	0	0	0	0
Total	42	33	32	107	5	12
'-' = Not available. Table 1 notes Table 1 note 1 WNV 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. Return to table 1 note * referrer Total clinical cases are the sum of confirmed and probable: WNV neurological and non-neurological syndromes, along with any unclassified or unspecified cases. Return to table 1 note 1 referrer Table 1 note 2 Likely related to travel outside the Province/Territory. These cases are included in either the total clinical cases or WNV asymptomatic infections. Return to table 1 note 2 referrer Table 1 note 3 Satisfies WNV 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 Héma-Quebec) and is subsequently brought to the attention of public health officials. Blood operators in Canada perform a supplementary WNV specific nucleic acid amplification test following any positive donor screen test result. Return to table 1 note 3 referrer Table 1 note 4 Saskatchewan provides counts of WNV neurological syndrome cases only. Return to table 1 note 4 referrer

Table 2: WNV mosquito surveillance^{table 2 note *} in Canada, as of September 18, 2018
Province / Territory	Number of positive mosquito pools	Number of mosquito pools tested	Percentage of positive mosquito pools (%)
Saskatchewan	50	761	6.57
Manitoba	168	1,909	8.80
Ontario	283	11,247	2.52
Québec	36	1,346	2.67
Total	537	15,263	3.52
Table 2 notes Table 2 note 1 Mosquito surveillance data is reported by the following four provinces: Saskatchewan, Manitoba, Ontario, and Québec. Return to table 2 note * referrer

Table 3: Total number of WNV mosquito pools tested by report week and by province/territory, 2018^{table 3 note ‡}
Province / Territory	Report Week																			Total
Province / Territory	22	23	24	25	26	27	28	29	30	31	32	33	34	35	36	37	38	39	40	Total
Saskatchewan	0	15	18	17	45	55	90	104	96	106	62	65	52	26	10	-	-	-	-	761
Manitoba	15	39	89	107	124	122	241	240	247	169	172	163	113	39	29	-	-	-	-	1,909
Ontario	0	0	0	0	842	955	1,024	963	1,073	1,059	1,156	1,124	1,133	998	920	-	-	-	-	11,247
Québec	0	69	77	105	105	113	109	109	110	99	123	122	102	103	0	-	-	-	-	1,346
Total	15	123	184	229	1,116	1,245	1,464	1,416	1,526	1,433	1,513	1,474	1,400	1,166	959	-	-	-	-	15,263
'-' = Not available. Table 3 notes Table 3 note 1 Detailed West Nile Virus mosquito surveillance data can be accessed through provincial/territorial websites. Return to table 3 note ‡ referrer

Figure 4. Text version below. — **Figure 4: Number of WNV positive dead wild birds in Canada^{figure 4 note *} by report week^{figure 4 note ‡}, 2018**

Table showing the reported number of dead birds tested positive for WNV in Canada, by province/territory and by report week, 2018 season.
Province	Jun	Jul	Aug	Sept	Oct	Nov	Total
British Columbia	0	0	0	0	0	0	0	0	0	0	0	2	0	0	0	-	-	-	-	-	-	-	-	-	-	-	-	2
Saskatchewan	0	0	0	0	0	0	0	0	2	0	0	0	1	0	-	-	-	-	-	-	-	-	-	-	-	-	-	3
Manitoba	0	0	0	0	3	0	0	0	0	7	0	3	1	0	-	-	-	-	-	-	-	-	-	-	-	-	-	14
Ontario	0	0	0	0	0	0	0	0	2	0	3	5	3	8	4	2	0	0	-	-	-	-	-	-	-	-	-	27
Québec	0	0	0	0	0	0	0	0	0	1	1	1	4	10	10	5	1	5	-	-	-	-	-	-	-	-	-	37
Total	0	0	0	0	3	0	0	0	2	1	4	8	13	18	19	9	1	5	-	-	-	-	-	-	-	-	-	83
'-' = Not available.

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2018-09-20

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