Overall description of human cases of potential exposure to rabies
In total, 320 human cases of potential exposure to rabies were reported in Nunavik from 2008 to 2017. Of these, 293 (92%) involved a dog. Cases associated with wildlife were mainly linked to Arctic foxes (68% of 23 cases). Overall, the victims were more often men (62% of all cases) than women, the proportion being greater among cases not associated with dogs (87% men) (Table 1). Children aged 5 to 14 years accounted for one third of all cases (Table 1). The majority of injuries were located in the upper limbs (40%) or lower limbs (35%).
Table 1. Demographic characteristics of potential human exposures to rabies in Nunavik for 2008-2017
Variable
|
All injuries
(n = 320)
|
Dogs
(n= 293*)
|
Other animals
(n=23*)
|
n
|
%
|
n
|
%
|
n
|
%
|
Sex
|
Male
|
198
|
61.9
|
176
|
60.1
|
20
|
87
|
Female
|
120
|
37.5
|
115
|
39.2
|
3
|
13
|
NA
|
2
|
0.6
|
2
|
0.7
|
0
|
0
|
Age group
|
[0-4]
|
30
|
9.4
|
30
|
10.2
|
0
|
0
|
[5-14]
|
110
|
34.4
|
102
|
34.5
|
5
|
21.7
|
[15-34]
|
114
|
35.6
|
101
|
34.5
|
12
|
52.2
|
[35+]
|
61
|
19.1
|
55
|
18.8
|
6
|
26.1
|
NA
|
5
|
1.6
|
5
|
1.7
|
0
|
0
|
* The total (dogs + other animals) is not 320 because animal type was unknown in 4 cases
The incidence of potential rabies exposure reported to the public health authority increased remarkably during the study period: a two-fold increase from 2014 (n=31) to 2017 (n=72) (Figure 1). Overall, the incidence was not uniformly distributed across months, nor across days of the week (K-S test: D = 1; critical value = 0.08) (p-value < 0.01), with May and August associated with 12% and 13% of cases, respectively, and Friday 18% (Figure 1).
The adjusted annual incidence by village over the study period varied between 0.45 and 4.6 cases per 1,000 inhabitants in Kangiqsualujjuaq and Kuujjuarapik, respectively (Table 2). Visually, incidences appear to be higher in the villages of Ungava Bay compared to Hudson Bay (Figure 2).
Table 2. Distribution of potential human exposures to rabies by village in Nunavik for 2008-2017
Village (sorted by decreasing adjusted annual incidence)
|
n
|
%
|
Mean annual incidence (per 1,000 people)
|
Mean adjusted annual incidence (per 1,000 people) 1
|
Kuujjuarapik
|
31
|
9.7
|
4.69
|
4.74
|
Kangirsuk
|
21
|
6.6
|
3.69
|
3.60
|
Quaqtaq
|
14
|
4.4
|
3.59
|
3.53
|
Kuujjuaq
|
88
|
27.5
|
3.50
|
3.68
|
Salluit
|
47
|
14.7
|
3.28
|
3.19
|
Inukjuak
|
48
|
15.0
|
2.76
|
2.72
|
Ivujivik
|
10
|
3.1
|
2.63
|
2.68
|
Umiujaq
|
10
|
3.1
|
2.19
|
2.08
|
Kangiqsujuaq
|
17
|
5.3
|
2.11
|
2.04
|
Aupaluk
|
4
|
1.2
|
2
|
2.73
|
Akulivik
|
7
|
2.2
|
1.09
|
1.04
|
Tasiujaq
|
3
|
0.9
|
0.95
|
0.88
|
Puvirnituq
|
14
|
4.4
|
0.81
|
0.74
|
Kangiqsualujjuaq
|
5
|
1.6
|
0.45
|
0.45
|
NA
|
1
|
0.3
|
-
|
-
|
Total
|
320
|
100
|
2.5
|
2.5
|
1 Cumulative incidences were standardized for both age and sex using direct standardization
PEP was recommended for 43% of the cases for which the information was available. It was more frequently recommended in cases involving wildlife (86%) compared to dogs (38%).
Sixty-two percent of dogs involved were held for observation following the exposure; a minor fraction (1.6%) of them were killed before the follow-up was over. Observation rate increased over the study period from 25% (3/12) in 2008, to 83% (60/72) in 2017.
Fifteen rabid animals (6.7% of all cases) were identified during the study period, of which 9 (60%) were dogs. Proportion of positive results was 4% among dogs, and 43% among wild animals. The number of rabid animals ranged from 0 to 2 per year, except for in 2015 and 2017, when it was 6 and 4, respectively. These animals were located in seven different villages with one, Ivujivik, accounting for 33% of all positive cases (Figure 2).
PEP was recommended for all confirmed exposures with only one exception; in this instance, careful examination of the case file revealed that the person was in contact with an animal carcass and took all the necessary precautions to avoid contamination while handling it. Therefore, the assessment at the time concluded there were no risk of exposure to rabies. PEP recommendation was a posteriori not required in 35% of cases, where the animal involved was tested and found not rabid.
The free text field included information in 152 dog-related cases (51.8% of all cases). Around 40% of these cases were coded as a dog reaction to a human threat, 17% occurred during play, and 7% were coded as a direct aggression by the dog, whereas the information was not useful in 38%. Most exposures during play involved children up to 15 y/o. For reaction due to a perceived threat, around 63% of all cases were seen in victims aged 15 y/o and older. Cases where the aggression was intended “predation” were more or less equally distributed between the four age groups (Table 3). The free text field for the nine cases associated with a rabid dog provided no information about the bite circumstances.
Children versus adults
The bivariate description showed differences between age groups. Notably, the age distribution included a cluster of very young victims (below 10 y/o) in both sexes, and another cluster in the early 20s in males (Figure 3). Accordingly, more males than females were observed in the two older age groups (Table 3). Very young children (0-4 y/o) were potentially exposed only through dogs and through bites (86.6 %), the exposure site for them was more frequently the head and neck (23.3%), and they were less frequently injured during the winter compared to the other age groups. PEP was more recommended more frequently for the oldest age group (15+ y/o), and one-third (34%) of PEP were administered to victims aged 15 to 34 y/o.
MCA was conducted on the 86 cases for which information was available for all variables of interest. The first two dimensions accounted for 39% and 14% of total inertia (amount of variation in the data), respectively, and so these variables were used for interpretation. Overall, the figure shows a partial association along the first dimension between the following case features: animal not being a dog, positive rabies test result, analysis of the animal, exposure through mucosa, and recommendation for PEP. The second dimension features some differences between cases aged 15-34 y/o and those older. The latter were relatively more associated with disseminated injury or injury to the lower limbs and PEP recommendation, whereas cases of 15-34 y/o were relatively more associated with injury to the upper limbs, head or neck, percutaneous exposure and no PEP recommendation. No obvious association with age groups was found except for age group 4 (35+ y/o), which was associated with the second dimension, determined by exposure site (upper and lower limbs) and exposure type (bite and percutaneous) (Figure 4).
Univariable logistic regression analysis showed that victims aged 0-14 y/o were more frequently females and were more likely to get injured by dogs compared to older victims (Table 4). No other variables were significantly associated with age group. No significant association was observed in the multivariable regression analysis of all types of exposure, whereas the head or neck as the exposure site was the only statistically significant result for dog-related exposures (Table 4).
Table 4. Logistic regression results using children as the reference group
Variable
|
Model a: All exposures
|
Model b: Exposures through dogs only
|
Univariable
|
Multivariable
|
Univariable
|
Multivariable
|
OR
(95% CI)
|
p-value
|
OR
(95% CI)
|
p-value
|
OR
(95% CI)
|
p-value
|
OR
(95% CI)
|
p-value
|
Sex
|
|
Male
|
1.00
|
-
|
1.00
|
-
|
1.00
|
-
|
1.00
|
-
|
Female
|
2.38
(1.49-3.85)
|
0.0003
|
1.37
(0.74-2.50)
|
0.23
|
2.32
(1.43- 3.85)
|
0.0006
|
1.54
(0.81-2.94)
|
0.19
|
Exposure site
|
|
Disseminated
|
1.00
|
-
|
1.00
|
-
|
1.00
|
-
|
1.00
|
-
|
Head and neck
|
3.30
(0.94 – 12.42)
|
0.07
|
3.38
(0.95-12.85)
|
0.06
|
3.67
(0.99 - 14.63)
|
0.05
|
3.75
(1.00-15.06)
|
0.05
|
Upper limbs
|
0.96
(0.31 – 3.11)
|
0.94
|
0.97
(0.31-3.18)
|
0.95
|
0.90
(0.28 - 3.01)
|
0.86
|
0.85
(0.26-2.87)
|
0.79
|
Lower limbs
|
1.14
(0.37 – 3.76)
|
0.82
|
1.16
(0.37-3.84)
|
0.80
|
1.05
(0.32 – 3.55)
|
0.93
|
1.05
(0.32-3.57)
|
0.93
|
Torso
|
3.00
(0.23 – 73.58)
|
0.41
|
2.59
(0.20-64.12)
|
0.48
|
2.67
(0.21 – 65.79)
|
0.46
|
2.36
(0.18-58.85)
|
0.52
|
Animal
|
|
Other
|
1.00
|
-
|
1.00
|
-
|
-
|
-
|
-
|
-
|
Dogs
|
3.05
(1.18 – 9.42)
|
0.03
|
2.22
(0.78-7.30)
|
0.15
|
-
|
-
|
-
|
-
|
Context
Ten participants at the local, regional and provincial levels were interviewed: eight were animal or human health professionals, and two were locals.
The management and reporting process in Nunavik for a human case of potential exposure to rabies can be described as follows (at the time of the interviews). If a victim injured by an animal seeks medical attention in Nunavik, the case is usually reported to and treated by the local community service centre (CLSC). All of the 14 Nunavik villages have a CLSC. Frontline nurses are in charge of case management and follow-up, which is guided by a treatment algorithm. The case is immediately reported to NRPHB and to MAPAQ, which provides expertise on rabies exposure risk if the animal involved is domestic, or passes it to Québec’s Ministry of Forests, Wildlife and Parks (MFFP) if it is a wild animal. At the local level, animal control agents, in collaboration with MAPAQ or MFFP (as applicable), are in charge of follow-up if the animal is traceable, and for preparing and sending the carcass to the CFIA rabies reference laboratory for testing.
The interviewees identified two major events related to case management processes. First, around 2014, the CFIA, which had previously been involved in rabies surveillance in animals, saw its role significantly reduced to just rabies diagnostic testing. Other activities, including carcass or head preparation and expedition, were transferred to other provincial and regional authorities, which led to more responsibilities for NRPHB and MAPAQ. Second, at the local level, health professionals also noted that a remarkable change in the processes and tools available for case management and reporting between 2015 and 2016. In brief, the documents that frontline health professionals relied on were modified and made available online to facilitate the decision-making process in case management.
Respondents did not mention differences across months or seasons specific to their roles and responsibilities. However, they stated that, in general, cases tended to be more frequent during summer. Some linked the dog-related injuries and potential exposure to rabies to activities such as boating and fishing, during which people often leave their dogs to roam. It also appears that dog population dynamics are affected by seasonal outbreaks of highly contagious infectious diseases such as parvovirus and distemper. From an exclusively wild animal perspective, participants pointed out that most cases of exposure involving fauna, and almost all rabies cases in wild animals, are seen during the cold season (October to March), due to activities such as hunting for fur-bearing animals or the scarcity of food resources in wild habitats during this season. These variations were further confirmed by the rabies test results in animals provided by the CFIA: more than 69% of the rabid animals observed during the study period were tested between December and March.
Interviewees pointed out some issues with animal control services; for example, positions tend to be very instable, leading to a lack of continuity at the local level. Moreover, a lack of education and awareness often leads to a lack of cooperation from locals, whether for dog control efforts, PEP or follow-up after an injury. Furthermore, participants said the effectiveness of such control requires greater involvement and commitment from officers.
Participants confirmed that there are no differences regarding their roles and activities in managing exposure cases associated with age. However, healthcare professionals were unanimous on the disproportionate over-representation of children compared to adults and the severity of the wounds seen in children under 5 y/o. Most respondents related these differences to the inappropriate behavior of children and adolescents toward dogs in Nunavik. As for adults, participants mentioned that the activities of hunting and mushing are risk factors, especially for males.
Table 3. Characteristics of potential human exposures to rabies by age group and percentage of the total in each group, Nunavik 2008-2017
Variables
|
Age groups
|
Total
|
[0-4]
|
[5-14]
|
[15-34]
|
[35+]
|
NA
|
n
|
%
|
n
|
%
|
n
|
%
|
n
|
%
|
n
|
%
|
n
|
%
|
Sex
|
Male
|
198
|
61.9
|
16
|
53.3
|
56
|
50.9
|
84
|
73.7
|
41
|
67.2
|
2
|
20.0
|
Female
|
120
|
37.5
|
14
|
46.7
|
54
|
49.1
|
30
|
26.3
|
20
|
32.8
|
1
|
40.0
|
NA
|
2
|
0.6
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
2
|
40.0
|
Exposure type
|
Bite
|
244
|
76.2
|
26
|
86.6
|
81
|
73.6
|
87
|
76.3
|
46
|
75.4
|
4
|
80.0
|
Percutaneous
|
8
|
2.5
|
0
|
0
|
5
|
4.5
|
2
|
1.8
|
1
|
1.6
|
0
|
0
|
Mucous
|
16
|
5
|
2
|
6.7
|
4
|
3.6
|
8
|
7.0
|
2
|
3.3
|
0
|
0
|
NA
|
52
|
16.2
|
2
|
6.7
|
20
|
18.2
|
17
|
14.9
|
12
|
19.7
|
1
|
20.0
|
Exposure site
|
Disseminated
|
15
|
4.7
|
2
|
6.7
|
4
|
3.6
|
3
|
2.6
|
6
|
9.8
|
0
|
0
|
Lower limbs
|
67
|
20.9
|
5
|
16.7
|
24
|
21.8
|
22
|
19.3
|
16
|
26.2
|
0
|
0
|
Upper limbs
|
77
|
24.1
|
6
|
20.0
|
24
|
21.8
|
36
|
31.6
|
11
|
18.0
|
0
|
0
|
Head and neck
|
32
|
10
|
7
|
23.3
|
15
|
13.6
|
8
|
7.0
|
2
|
3.3
|
0
|
0
|
Trunk
|
3
|
0.9
|
1
|
3.3
|
1
|
0.9
|
0
|
0.0
|
1
|
1.6
|
0
|
0
|
NA
|
126
|
39.4
|
9
|
30.0
|
42
|
38.2
|
45
|
39.5
|
25
|
41.0
|
5
|
100
|
Animal type
|
Dog
|
293
|
91.6
|
30
|
100
|
102
|
92.7
|
101
|
88.6
|
55
|
90.2
|
5
|
100
|
Other
|
23
|
7.2
|
0
|
0
|
5
|
4.5
|
12
|
10.5
|
6
|
9.8
|
0
|
0
|
NA
|
4
|
1.2
|
0
|
0
|
3
|
2.7
|
1
|
0.9
|
0
|
0
|
0
|
0
|
PEP
|
Recommended
|
99
|
30.9
|
7
|
23.3
|
27
|
24.5
|
34
|
29.8
|
28
|
45.9
|
3
|
60.0
|
Not recommended
|
133
|
41.6
|
16
|
53.3
|
41
|
37.3
|
56
|
49.1
|
20
|
32.8
|
0
|
0
|
NA
|
88
|
27.5
|
7
|
23.3
|
42
|
38.2
|
24
|
21.1
|
13
|
21.3
|
2
|
40.0
|
Exposure season
|
Winter
|
65
|
20.3
|
3
|
10.0
|
25
|
22.7
|
24
|
21.1
|
11
|
18.0
|
2
|
40.0
|
Spring
|
80
|
25
|
9
|
30.0
|
25
|
22.7
|
30
|
26.3
|
16
|
26.2
|
0
|
0
|
Summer
|
93
|
29.1
|
11
|
36.7
|
33
|
30.0
|
34
|
29.8
|
14
|
23.0
|
1
|
20.0
|
Autumn
|
81
|
25.3
|
6
|
20.0
|
27
|
24.5
|
26
|
22.8
|
20
|
32.8
|
2
|
40.0
|
NA
|
1
|
0.3
|
1
|
3.3
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
Exposure day
|
Weekday
|
237
|
74.1
|
19
|
63.3
|
85
|
77.3
|
87
|
76.3
|
42
|
68.9
|
4
|
80.0
|
Weekend
|
83
|
25.9
|
11
|
36.7
|
25
|
22.7
|
27
|
23.7
|
19
|
31.1
|
1
|
20.0
|
NA
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
Animal test result
|
Positive
|
15
|
4.7
|
1
|
3.3
|
2
|
1.8
|
10
|
8.8
|
2
|
3.3
|
0
|
0
|
Negative
|
210
|
65.6
|
19
|
63.3
|
72
|
65.5
|
74
|
64.9
|
41
|
67.2
|
4
|
80
|
NA
|
89
|
27.8
|
10
|
33.3
|
33
|
30.0
|
28
|
24.6
|
17
|
27.9
|
1
|
20
|
N/App
|
6
|
1.9
|
0
|
0
|
3
|
2.7
|
2
|
1.8
|
1
|
1.6
|
0
|
0
|
Exposure circumstances
[1]
|
Play/ communication
|
26
|
17.1
|
7
|
43.8
|
12
|
21.8
|
5
|
10.2
|
1
|
3.6
|
1
|
25.0
|
Reaction
|
59
|
38.8
|
5
|
31.2
|
16
|
29.1
|
25
|
51.0
|
12
|
42.9
|
1
|
25.0
|
Aggression/ predation
|
10
|
6.6
|
2
|
12.5
|
3
|
5.5
|
1
|
2.0
|
4
|
14.3
|
0
|
0
|
Inconclusive
|
51
|
33.6
|
1
|
6.2
|
24
|
43.6
|
16
|
32.7
|
10
|
35.7
|
0
|
0
|
N/App
|
6
|
3.9
|
1
|
6.2
|
0
|
0
|
2
|
4.1
|
1
|
3.6
|
2
|
50.0
|
[1] Cases including dogs only (N= 152)