West Nile virus and other mosquito-borne diseases - national surveillance report - August 27 to September 2, 2017 (Week 35)

West Nile Virus

Canada

Humans

During week 35, August 27 to September 2, 2017, one confirmed clinical case of West Nile Virus (WNV) from Ontario was reported to the Public Health Agency of Canada (PHAC). Retrospectively, an additional 17 clinical cases were reported; eleven from Ontario, two from Alberta and four from Québec. Québec also reported one asymptomatic case.

As of week 35, forty-two clinical cases and four asymptomatic infections (ON=36, BC=1, AB=3, MB=1, QC=5) have been reported to PHAC. Of the forty-two clinical cases, eighteen (43%) were classified as WNV neurological syndrome. No deaths associated with WNV have been reported.

Mosquitoes

As of initial surveillance, 13,563 mosquito pools have been tested for WNV in Canada: Québec (735), Ontario (11,440), Manitoba (1,001), and Saskatchewan (387).

A total of 434 positive pools of WNV have been found in the following four provinces: 370 in Ontario [Brant County (2), Chatham-Kent (3), Durham Region (10), Eastern Ontario (4), Halton Region (35), Hamilton (29), Haliburton-Kwartha-Pine Ridge District (1), Hastings and Prince Edward Countries (13), Huron County (2), Kingston-Frontenac and Lennox and Addington (5), Lambton (2), Middlesex-London (6), Niagara Region (13), Northwestern (1), Ottawa (25), Oxford County (1), Peel (98), Perth District (6), Peterborough County-City (2), Renfrew County and District (2), Simcoe Muskoka District (2), Toronto (59), Waterloo (3), Wellington-Dufferin-Guelph (3), Windsor-Essex County (28), and York Regional (15)]; forty-one in Manitoba [(Winnipeg (13), Southern (5), Interlake Eastern (7), and Prairie Mountain (16)]; thirteen in Québec [Capitale-Nationale (1), Montérégie (7), Montréal (3), and Outaouais (2)]; and ten in Saskatchewan.

Birds

As of week 35, the Canadian Wildlife Health Cooperative has tested 131 dead birds for WNV [Quebec (75), Ontario (43), Saskatchewan (9), Manitoba (2) and British Columbia (2)]. Of these, eighty-two were positive: forty-six in Quebec, two in Manitoba, twenty-eight in Ontario, and six in Saskatchewan.

Domestic Animals

As of week 35, fifteen horses with WNV infection were reported to the Canadian Food Inspection Agency (CFIA): three in Alberta, seven in Ontario, and five in Saskatchewan. Also one pheasant with WNV infection located in Québec was reported to the CFIA.

United States and U.S. territories

As of September 5, 2017, 526 human cases of WNV have been reported by the Centers for Disease Control and Prevention (CDC). Of these, 303 (58%) were classified as neuroinvasive disease and 223 (42%) as non-neuroinvasive disease. In addition, ninety-seven presumptive viremic blood donors have been identified.

Detailed information can be accessed via the CDC web site.

Europe and Neighbouring Countries

As of August 31, 2017, the European Centre for Disease Prevention and Control (ECDC) reported a total of 107 (confirmed and probable) cases of West Nile fever [Austria (6), Greece (37), Hungary (5), Israel (4), Italy (27), Romania (16), and Serbia (12)].

Detailed information can be accessed via the ECDC web site.

Other Mosquito-borne Diseases

Canada

Eastern Equine Encephalitis virus

No human cases of eastern equine encephalitis virus have been reported to the Public Health Agency of Canada in 2017.

California Serogroup virus

Since January 1, 2017, fifteen human cases of laboratory-confirmed cases/exposures of California serogroup virus were diagnosed by the National Microbiology Laboratory in Canada: Alberta (2), Saskatchewan (2), Manitoba (1), Ontario (1), Quebec (8), and Nova Scotia (1). Of these cases, eleven cases were further classified as Jamestown Canyon virus and one Snowshoe hare virus.

Figure 1 text equivalent

Map showing geographic distribution of human cases of WNV in Canada.

As of surveillance week 35, ending September 2, 2017, there are forty-six human cases of WNV in Canada; thirty-six from Ontario, one from British Columbia, three from Alberta, one from Manitoba, and five from Québec.

Figure 2 Footnote 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 figure 2 footnote * referrer

Figure 2 text equivalent

As of week 35, ending September 2, 2017, there are forty-six human clinical cases and asymptomatic infections associated with WNV in Canada.

Table showing human clinical cases and asymptomatic infections associated with WNV in Canada, by province or territory and by week monitoring, dated 2 September 2017

	Report Week Figure 2 Footnote *																													Total
	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
British Columbia	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0	0	0	0	0	0	0	0	0	0	0	0	0	1
Ontario	0	0	0	0	0	0	0	1	0	0	1	6	2	5	2	7	5	6	1	0	0	0	0	0	0	0	0	0	0	36
Alberta	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	3	0	0	0	0	0	0	0	0	0	0	0	0	3
Manitoba	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0	0	0	0	0	0	0	0	0	0	0	0	1
Québec	0	0	0	0	0	0	0	0	0	0	0	0	0	2	1	1	1	0	0	0	0	0	0	0	0	0	0	0	0	5
Total	0	0	0	0	0	0	0	1	0	0	1	6	2	7	3	9	10	6	1	0	0	0	0	0	0	0	0	0	0	46

Figure 3 Footnote 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 figure 3 footnote * referrer

Figure 3 text equivalent

Table showing WNV human clinical cases and asymptomatic infections in Canada, by report week for selected years

	Report Week Figure 3 Footnote *																																		Total
	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	48	49	50
2017	0	0	0	0	0	0	0	1	0	0	1	6	2	7	3	9	10	6	1	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	46
2016	0	0	0	1	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	0	0	0	106
2014	0	0	0	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	0	0	0	22
2012	0	0	0	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	0	0	0	450
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	0	0	0	2 378
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	0	0	0	1 450

Table 1: West Nile virus human clinical cases and asymptomatic infections by province/territory for the current report week and year to date, 2017 season

Province/Territory	week 35: August 27 to September 2, 2017
	WNV Cases			Total clinical casesTable 1 Footnote 1	# of travel related WNV casesTable 1 Footnote 2	# of asymptomatic WNV infectionsTable 1 Footnote 3
	Neurological syndrome	Non-Neurological syndrome	Unclassified / Unspecified
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
Québec	0	0	0	0	0	0
Ontario	0	0	1	1	0	0
Manitoba	0	0	0	0	0	0
SaskatchewanTable 1 Footnote 4	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 Territories	0	0	0	0	0	0
Nunavut	0	0	0	0	0	0
Total	0	0	1	1	0	0
Year to date: January 1 to September 2, 2017
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
Québec	3	1	0	4	0	1
Ontario	12	14	8	34	8	2
Manitoba	1	0	0	1	1	0
SaskatchewanTable 1 Footnote 4	0	-	-	-	-	-
Alberta	2	1	0	3	0	0
British Columbia	0	0	0	0	0	1
Yukon Territory	0	0	0	0	0	0
Northwest Territories	0	0	0	0	0	0
Nunavut	0	0	0	0	0	0
Total	18	16	8	42	9	4
Table 1 Footnote 1 Total clinical cases is 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 1 footnote 1 referrer Table 1 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 1 footnote 2 referrer Table 1 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 1 footnote 3 referrer Table 1 Footnote 4 Saskatchewan provides counts of WNV neurological syndrome cases only. Return to table 1 footnote 4 referrer

Table 2: Number of mosquito pools tested for West Nile virus and number of positive mosquito pools by province/territory, 2017 season

Province	Year to date: January 1 to September 2, 2017
	Number of positive mosquito pools	Number of mosquito pools tested	Percentage of positive mosquito pools (%)
Quebec	13	735	1.77
Ontario	370	11,440	3.23
Manitoba	41	1,001	4.10
Saskatchewan	10	387	2.58
Alberta	-	-	-
British Columbia	-	-	-
Newfoundland and Labrador	-	-	-
Prince Edward Island	-	-	-
Nova Scotia	-	-	-
New Brunswick	-	-	-
Yukon Territory	-	-	-
Northwest Territory	-	-	-
Nunavut	-	-	-
Total	434	13,563	3.20

Table 3: Total number of WNV mosquito pools tested by report week and by province/ territory, 2017 season^{Table 3 Footnote 1}

Province / Territory	Report week of 2017																						Total
	19	20	21	22	23	24	25	26	27	28	29	30	31	32	33	34	35	36	37	38	39	40
Québec	-	-	-	-	-	-	-	-	147	147	147	147	0	147	0	0	0						735
Ontario	13	15	43	84	194	299	718	794	964	1,003	1,037	1,053	1,168	1,015	1,116	993	931						11,440
Manitoba	-	-	-	-	15	45	48	16	60	93	96	113	178	122	86	104	25						1,001
Saskatchewan	-	-	-	-	6	20	11	18	25	31	38	46	61	52	39	40	0						387
Alberta	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-								0
British Columbia	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-								0
Newfoundland and Labrador	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-								0
Prince Edward Island	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-								0
Nova Scotia	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-								0
New Brunswick	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-								0
Yukon Territory	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-								0
Northwest Territories	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-								0
Nunavut	-	-	-	-	-	-	-	-	-	-	-	-	-	-	-								0
Total	13	15	43	84	215	364	777	828	1,196	1,274	1,318	1,359	1,407	1,336	1,241	1,137	956	0	0	0	0	0	13,563
Table 3 Footnote 1 Detailed West Nile virus mosquito surveillance data can be accessed through Provincial/ Territorial websites Return to table 3 footnote 1 referrer

Figure 4 Footnote 1

Not all provinces are conducting dead bird surveillance as part of their own WNV surveillance program. However, WNV positive dead birds may be identified through the National Wildlife Disease Surveillance Program of the Canadian Wildlife Health Cooperative.

Return to figure 4 footnote ¶ referrer

Text Equivalent

As of week 35, ending September 2 in 2017, there are eighty-two WNV cases in birds, in Canada.

Table showing the reported number of dead birds tested positive for WNV in Canada, by province/territory and by report week, 2017 season.

Report Week
	14	15	16	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	48	49	50	Total
Manitoba	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	2	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	2
Ontario	0	0	1	0	0	0	0	0	0	0	0	3	1	1	0	0	2	5	1	7	4	3	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	28
Québec	0	0	0	0	0	0	0	0	0	0	0	0	0	0	4	3	9	10	7	6	2	5	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	46
Saskatchewan	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	1	0	3	2	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	6
Total	0	0	1	0	0	0	0	0	0	0	0	3	1	1	4	3	13	16	8	16	8	8	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	82

Figure 5 Footnote 1

Not all provinces are conducting dead bird surveillance as part of their own WNV surveillance program. However, WNV positive dead birds may be identified through the National Wildlife Disease Surveillance Program of the Canadian Wildlife Health Cooperative.

Return to figure 5 footnote ¶ referrer

Figure 5 text equivalent

Table showing percentage of dead birds tested positive for WNV in Canada by report week in 2012, 2015, 2016 and 2017 and the number of dead birds that tested positive for WNV by report week, 2017 season

	Report Weeks																																	Total
	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	48	49
2013 Percentage positive	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	100	0	17	0	0	0	0	0	43.5%
2014 Percentage positive	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	15	20	29	31	0	27	75	0	20	0	50	0	0	0	0	0	0	0	20.4%
2015 Percentage positive	0	0	0	0	0	0	0	100	0	0	0	100	83	60	73	0	25	67	83	57	50	80	67	0	21	0	0	0	0	50	0	0	0	51.0%
2016 Percentage positive	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	33	50	23	25	80	43	43	20	36	0	80	0	0	0	0	0	0	0	26.2%
2017 Percentage positive	-	0	0	0	0	0	0	0	100	33	50	100	33	87	84	62	80	67	89
2017 Number positive	-	0	0	0	0	0	0	0	3	1	1	4	3	13	16	8	16	8	8															82