West Nile virus and other mosquito-borne diseases national surveillance report — October 22 to October 28, 2017 (Week 43)

West Nile Virus

Canada

Humans

During week 43, October 22 to October 28, 2017, one new case of West Nile Virus (WNV) was reported from Québec to the Public Health Agency of Canada (PHAC).  Retrospectively, five additional cases were reported by two provinces: three in Québec and two in Ontario.

As of week 43, 179 clinical cases and six asymptomatic infections have been reported to the PHAC by five provinces (Québec [19], Ontario [154], Manitoba [4], Alberta [7], and British Columbia [1]).  Of the 179 clinical cases, sixty-seven (37%) were classified as WNV neurological syndrome, sixty-eight (38%) as WNV Non-neurological syndrome, and forty-four (25%) as unclassified.  A total of 23 travel-related cases were reported.  As of October 28, six deaths associated with West Nile virus have been reported to the Public Health Agency of Canada during the 2017 season.

Mosquitoes

As of initial surveillance, 17,374 mosquito pools have been tested for WNV in Canada: Québec (1,849), Ontario (14,076), Manitoba (1,028), and Saskatchewan (421).

A total of 544 positive pools of WNV have been found in the following four provinces: 409 in Ontario [Brant County (2), Chatham-Kent (3), Durham Region (10), Eastern Ontario (5), Halton Region (36), Hamilton (31), Haliburton-Kwartha-Pine Ridge District (1), Hastings and Prince Edward Countries (13), Huron County (2), Kingston-Frontenac and Lennox and Addington (5), Lambton (2), Leeds, Grenville and Lanark District Health Unit (1), Middlesex-London (7), Niagara Region (15), Northwestern (1), Ottawa (35), Oxford County (1), Peel (114), Perth District (6), Peterborough County-City (2), Renfrew County and District (2), Simcoe Muskoka District (2), Toronto (62), Waterloo (3), Wellington-Dufferin-Guelph (3), Windsor-Essex County (29), and York Regional (16)]; forty-one in Manitoba[(Winnipeg (13), Southern (5), Interlake Eastern (7), and Prairie Mountain (16)]; eighty-four in Québec [Capitale-Nationale (9), Mauricie et du Centre-du-Québec (6), Montréal (10), Outaouais (3), Laval (5), Lanaudière (9), Laurentides (42)]; and ten in Saskatchewan.

Birds

As of week 43, the Canadian Wildlife Health Cooperative has tested 208 dead birds for WNV (Northwest Territories [1], Prince Edward Island [1], Quebec [111], Ontario [74], Saskatchewan [16], Manitoba [2], Alberta [1], and British Columbia [2]). Of these, 136 were positive: eighty-two in Quebec, two in Manitoba, forty-one in Ontario, and eleven in Saskatchewan.

Domestic Animals

The Canadian Food Inspection Agency has reported fifty-one horses with WNV infection in the following six provinces: Québec (7), Ontario (21), Manitoba (1), Saskatchewan (8), Alberta (10), and British Columbia (4). 

United States and U.S. territories

As of October 31, 2017, 1,697 human cases of WNV have been reported by the Centers for Disease Control and Prevention. Of these, 1,121 (66%) were classified as neuroinvasive disease and 576 (34%) as non-neuroinvasive disease. Ninety-seven deaths have been reported during the season. In addition, 213 presumptive viremic blood donors have been identified.

Detailed information can be accessed via the CDC web site.

Europe and Neighbouring Countries

As of November 2, 2017, the European Centre for Disease Prevention and Control reported a total of 280 (confirmed and probable) cases of West Nile fever (Austria [4], Bulgaria [1], Croatia [5], France [1], Greece [48], Hungary [20], Israel [28], Italy [55], Romania [64, Serbia [49], and Turkey [5]). Twenty deaths due to West Nile fever have been reported since the start of the season.

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 (EEEV) have been reported to the Public Health Agency of Canada in 2017.  As of October 30, there have been two horses that tested positive for  EEEV in Ontario.

California Serogroup virus

Since January 1, 2017, forty-five human cases of laboratory-confirmed cases/exposures of California serogroup virus were diagnosed by the National Microbiology Laboratory in Canada: British Columbia (1), Alberta (5), Saskatchewan (5), Manitoba (1), Ontario (1), Quebec (27), New Brunswick (3), and Nova Scotia (2).  Of these cases, twenty-seven were further classified as Jamestown Canyon virus and one Snowshoe hare virus.

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
2017	0	0	0	0	0	0	0	1	0	1	1	7	3	8	9	23	27	30	24	11	19	9	7	4	0	0	1						185
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			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			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			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			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			1,450

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

Figure 4 text equivalent

As of week 43, ending October 28 in 2017, there are 136 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
	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
Manitoba	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		2
Ontario	0	0	0	0	0	0	0	0	3	1	1	0	0	2	6	1	7	4	3	5	1	0	2	2	1	0	1		41
Québec	0	0	0	0	0	0	0	0	0	0	0	5	3	9	10	7	8	10	15	6	3	3	2	1	0	0	0		82
Saskatchewan	0	0	0	0	0	0	0	0	0	0	0	0	0	0	2	0	4	3	1	1	0	0	0	0	0	0	0		11
Total	0	0	0	0	0	0	0	0	3	1	1	5	3	13	18	8	19	17	19	12	4	3	4	3	1	0	1		136

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	50
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	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	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	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	0	26.2%
2017 Percentage positive	-	0	0	0	0	0	0	0	100	33	50	100	33	87	86	57	76	74	86	80	67	60	33	60	100	0	50
2017 Number positive	-	0	0	0	0	0	0	0	3	1	1	5	3	13	18	8	19	17	19	12	4	3	4	3	1	0	1								136