What is the real number of Lyme disease cases in Canada?

BMC Public Health

Table 2 Comparison of reported human LD case incidence (per 100,000 population) in Canadian surveillance (probable and confirmed cases combined) in 2014 to 2016 [12, 13] with comparable data from the neighbouring US states (incidence for 2014 to 2015 obtained from [47] and for 2016 from https://www.cdc.gov/lyme/stats/tables.html, with State population estimates obtained from the US census: https://www.census.gov/data/tables/time-series/demo/popest/2010s-national-total.html#par_textimage_2011805803). These data were chosen as they are contemporaneous with similar data presented in [22]. Province abbreviations are AB Alberta, BC British Columbia, MB Manitoba, ON Ontario, QC Quebec, NB New Brunswick, NS Nova Scotia. State abbreviations are MT Montana, ND North Dakota, MN Minnesota, WI Wisconsin, MI Michigan, NY New York, VT Vermont, NH New Hampshire, ME Maine, WA Washington

Canada	Incidence in Canada			Neighbouring US States	Incidence in the US (fold difference)^a
Canada	2014	2015	2016	Neighbouring US States	2014	2015	2016
AB^b	0.2	0.3	0.2	MT	0.5 (2.5)	0.2 (0.7)	1.2 (6.0)
MB	2.7	2.3	3.9	ND,MN	14.4 (5.3)	19.1 (8.3)	20.9 (5.4)
ON	1.7	2.7	2.7	MN,WI,MI,NY	11.8 (6.9)	14.3 (5.3)	13.6 (5.0)
QC	1.5	1.9	2.1	NY,VT,NH,ME	23.3 (15.5)	21.7 (11.4)	22.8 (10.9)
NB	0.7	1.5	1.5	ME	87.9 (62.8^c)	74.7 (24.9^c)	86.4 (28.8^c)
NS	12.1	26.1	34.4	ME	87.9 (7.3)	74.7 (2.9)	86.4 (2.5)
BC	0.1	0.3	0.8	WA	0.1 (1.0)	0.2 (0.7)	0.2 (0.3)

^aThe difference between incidence in the US States compared to Canadian Provinces. Note that there are slight differences amongst Canadian provinces in the data provided in surveillance, and consequently the capacity to separate endemically acquired from travel-acquired cases. ^bOnly travel-related cases have been found in Alberta and neighbouring US states. ^cThis difference accounts for approximately 50% of reported cases in Maine being EM rash only without laboratory test results (https://www.maine.gov/dhhs/mecdc/infectious-disease/epi/vector-borne/lyme/documents/2017-Lyme-Surveillance-Report.pdf), which would not at the time have been reported in NB