West Nile virus and other mosquito-borne diseases national surveillance report - September 10 to September 16, 2017 (Week 37)

West Nile Virus

Canada

Humans

During week 37, September 10 to September 16, 2017, three confirmed clinical case of West Nile Virus (WNV) from Ontario were reported to the Public Health Agency of Canada (PHAC). Retrospectively, twenty-nine additional cases were reported, twenty-eight in Ontario and one in Québec.

As of week 37, 103 clinical cases and six asymptomatic infections have been reported to the PHAC by five provinces (Ontario [98], Québec [6], Manitoba [1], Alberta [3], and British Columbia [1]. Of the 103 clinical cases, thirty-eight (37%) were classified as WNV neurological syndrome. As of September 16, five 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, 15,704 mosquito pools have been tested for WNV in Canada: Québec (1,469), Ontario (12,820), Manitoba (1,028), and Saskatchewan (387).

A total of 518 positive pools of WNV have been found in the following four provinces: 398 in Ontario [Brant County (2), Chatham-Kent (3), Durham Region (10), Eastern Ontario (5), 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 (14), Northwestern (1), Ottawa (34), Oxford County (1), Peel (111), 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 (15)]; forty-one in Manitoba [(Winnipeg (13), Southern (5), Interlake Eastern (7), and Prairie Mountain (16)]; sixty-nine in Québec; and ten in Saskatchewan.

Birds

As of week 37, the Canadian Wildlife Health Cooperative has tested 150 dead birds for WNV [Quebec (86), Ontario (51), Saskatchewan (9), Manitoba (2) and British Columbia (2)]. Of these, ninety-four were positive: fifty-two in Quebec, two in Manitoba, thirty-four in Ontario, and six in Saskatchewan.

Domestic Animals

As of week 37, thirty-two horses with WNV infection were reported to the Canadian Food Inspection Agency (CFIA): four in Québec, thirteen in Ontario, six in Saskatchewan, five in Alberta, and four in British Columbia.

United States and U.S. territories

As of September 19, 2017, 875 human cases of WNV have been reported by the Centers for Disease Control and Prevention (CDC). Of these, 537 (61%) were classified as neuroinvasive disease and 338 (39%) as non-neuroinvasive disease. In addition, 143 presumptive viremic blood donors have been identified.

Detailed information can be accessed via the CDC web site.

Europe and Neighbouring Countries

As of September 14, 2017, the European Centre for Disease Prevention and Control (ECDC) reported a total of 138 (confirmed and probable) cases of West Nile fever [Austria (2), Greece (40), Hungary (10), Israel (9), Italy (27), Romania (22), and Serbia (28)].

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 37, ending September 16, 2017, there are 109 human cases of WNV in Canada; ninety-eight from Ontario, one from British Columbia, three from Alberta, one from Manitoba, and six 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 37, ending September 16, 2017, there are 109 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 16 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	3	6	4	16	13	29	14	2	3	0	0	0	0	0	0	0	0	98
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	1	0	0	0	0	0	0	0	0	0	0	0	6
Total	0	0	0	0	0	0	0	1	0	0	1	6	3	8	5	18	18	30	14	2	3	0	0	0	0	0	0	0	0	109

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	3	8	5	18	18	30	14	2	3	0	0	0	0	0	0	0	0	0	0	0	0	0	109
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

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 37, ending September 16 in 2017, there are ninety-four 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	5	1	0	0	0	0	0	0	0	0	0	0	0	0	0	34
Québec	0	0	0	0	0	0	0	0	0	0	0	0	0	0	4	3	9	10	7	7	6	5	1	0	0	0	0	0	0	0	0	0	0	0	0	0	0	52
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	17	12	8	6	1	0	0	0	0	0	0	0	0	0	0	0	0	0	94

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	77	67	89	86	100
2017 Number positive	-	0	0	0	0	0	0	0	3	1	1	4	3	13	16	8	17	12	8	6	1													94