Table 1.
Tick encounter rate, DTV prevalence, and ERI for adult and nymphal Ixodes scapularis ticks collected at the Wells National Estuarine Research Reserve, Wells, ME, 2018–2021
| Stage | Year | Tick Encounter Rate*† | Prevalence‡§ | ERI†‖ | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Total | Mean (95% CI) | Significance | Total | + | % (95% CI) | Significance | Mean (95% CI) | Significance | ||
| Adult | 2018 | 443 | 22.2 (16.1–28.3) | B | 416 | 15 | 3.6 (1.8–5.4) | A¶ | 1.3 (0.4–2.1) | A |
| 2019 | 691 | 34.2 (26.1–42.3) | A | 653 | 10 | 1.5 (0.6–2.5) | A | 0.6 (0.2–1.1) | AB | |
| 2020 | 353 | 35.3 (27.4–43.2) | A | 353 | 4 | 1.1 (0.0–2.2) | A | 0.6 (0.0–1.1) | B | |
| 2021 | 551 | 34.7 (26.8–42.7) | A | 542 | 11 | 2.0 (0.8–3.2) | A | 0.9 (0.3–1.5) | AB | |
| All years | 2,038 | – | – | 1,964 | 40 | – | – | – | – | |
| Nymph | 2018 | 156 | 8.3 (5.8–10.7) | B | 138 | 0 | 0.0 | A | 0.0 | A |
| 2019 | 322 | 17.0 (11.7–22.2) | A | 226 | 2 | 0.9 (0.0–2.1) | A | 0.2 (0.0–0.5) | A | |
| 2020 | 10 | 1.0 (0.3–1.7) | D | 10 | 0 | 0.0 | A | 0.0 | A | |
| 2021 | 50 | 3.0 (2.0–4.0) | C | 50 | 0 | 0.0 | A | 0.0 | A | |
| All years | 538 | – | – | 424 | 2 | – | – | – | – | |
DTV = deer tick virus; ERI = entomological risk index.
*
Mean number of ticks collected/hour; N = 100 plots/year.
†
Same letters indicate that values are not statistically different (pairwise Wilcoxon rank sum tests, P <0.05).
‡
Number of DTV-positive ticks/total tested.
§
Same letters indicate that values are not statistically different (Fisher’s exact test, P <0.05).
‖
Mean number of infected ticks collected/hour; N = 100 plots/year.4
¶
DTV prevalence was marginally higher in 2018 than in 2019 and 2020, both P = 0.09.