Table 1. Estimated seroprevalence of Borrelia burgdorferi sensu lato among forestry workers by epidemiological characteristics, northern France, 2019–2020.

Characteristics	Participants n = 1,778a	Positive	Weighted seroprevalence		p value
		n	%	95% CI
Sex
Male	1,715	254	16.3	14.6–18.1	0.006
Female	63	2	3.7	1.0–12.5
Age (years)
18–30	326	18	5.1	3.3–8.0	< 0.001
31–40	377	32	8.9	6.3–12.3
41–50	430	39	9.9	7.4–13.2
51–60	520	126	26.6	22.9–30.6
> 60	125	41	35.8	28.0–44.3
Type of occupation (nine missing values)
Forest machine operator	320	32	11.8	8.5–16.2	< 0.001
Forest technician/ranger	357	80	23.1	19.1–27.7
Gardener/landscaper	20	2	13.1	3.8–36.8
Hunting technology/gamekeeper/ fishery guardian	144	12	8.6	5.1–14.2
Silviculturist	289	42	17.0	12.9–22.0
Woodcutter	622	86	14.1	11.6–17.0
Other	17	1	3.2	0.5–17.3
Geographical area of workb
Eastern	673	148	21.3	18.5–24.3	< 0.001
Central	401	39	8.6	6.4–11.3
Western	396	21	5.5	3.7–8.0
Auvergne	164	27	15.3	10.9–21.0
Limousin	144	21	14.4	9.8–20.6
Nationality (72 missing values)
French	1,659	241	15.8	14.1–17.7	0.02
Other EU countries	47	2	4.5	1.2–14.7
Number of years in forestry sector
1–5	241	16	7.0	4.3–11.1	< 0.001
6–10	242	13	5.0	3.0–8.3
11–20	449	37	8.3	6.1–11.2
21–30	406	68	18.2	14.6–22.3
31–40	317	85	28.8	24.1–33.9
> 40	123	37	35.0	27.1–43.7
Average weekly time in forest (hours) (19 missing values)
< 10	160	13	7.3	4.4–12.0	< 0.001
10–20	199	32	16.4	11.9–22.2
> 20	1,400	207	16.4	14.5–18.4
Tick bites (28 missing values)
No	182	13	7.6	4.6–12.3	0.002
Yes	1,568	236	16.2	14.4–18.1
If Yes, time from the last tick bite (one missing value)
< 1 year	1,072	186	18.5	16.3–21.0	< 0.001
> 1 year	495	50	10.8	8.4–13.9
If Yes, number of tick bites during the last year (five missing values)
0	494	52	11,4	8.9–14.6	< 0.001
1–12	809	127	16.9	14.4–19.7
13–24	131	30	22.8	16.3–30.9
> 24	129	32	26.9	19.9–35.4
If bitten last year, have you seen a red rash around the bite? (nine missing values)
No	963	161	18.1	15.7–20.9	0.5
Yes	91	21	22.3	15.0–31.9
Do not know	9	3	28.1	8.7–61.6
Exposed to tick bites (33 missing values)
No	220	16	7.9	5.0–12.3	< 0.001
Yes	1,525	233	16.4	14.6–18.4
Area of LB incidencec
Low	266	13	4.4	2.5–7.6	< 0.001
Medium	608	65	10.7	8.6–13.3
High	904	178	19.9	17.5–22.5

CI: confidence interval; EU: European Union; LB: Lyme borreliosis.

^a One blood sample could not be analysed.

^b Eastern includes Alsace, Lorraine, Champagne-Ardenne, Bourgogne and Franche-Comté regions; central includes Nord-Pas-De-Calais, Picardie, Île-de-France, Haute-Normandie and Centre regions; western includes Basse-Normandie, Bretagne and Pays-de-la-Loire regions.

^c Incidences estimated by the sentinel network in 2018: low < 50 cases per100,000 inhabitants, medium 50–100 cases per 100,000 inhabitants, high > 100 cases per 100,000 inhabitants.