Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USA.
Parasit Vectors. 2024 Feb 1;17(1):50. doi: 10.1186/s13071-024-06146-3.
The majority of vector-borne disease cases in the USA are caused by pathogens spread by ticks, most commonly the blacklegged tick, Ixodes scapularis. Personal protection against tick bites, including use of repellents, is the primary defense against tick-borne diseases. Tick repellents registered by the Environmental Protection Agency (EPA) are well documented to be safe as well as effective against ticks. Another group of tick repellent products, 25(b) exempt or minimum risk products, use alternative, mostly botanically derived, active ingredients. These are considered to pose minimal risk to human health and therefore are exempt from EPA registration; efficacy testing is not mandated for these products.
We used a finger bioassay to evaluate the repellency against I. scapularis nymphs for 11 formulated 25(b) exempt products together with two positive control DEET-based EPA registered products. Repellency was assessed hourly from 0.5 to 6.5 h after product application.
The DEET-based products showed ≥ 97% repellency for all examined timepoints. By contrast, an average of 63% of ticks were repelled in the first 1.5 h after application across the 11 25(b) exempt products, and the average fell to 3% repelled between 2.5 and 6.5 h. Ten of the 11 25(b) exempt products showed statistically similar efficacy to DEET-based products at 30 min after application (repellency of 79-97%). However, only four 25(b) exempt products maintained a level of repellency similar to DEET-based products (> 72%) at the 1.5-h mark, and none of these products were effective in repelling ticks at the timepoints from 2.5 to 6.5 h after application.
Neither the claims on the labels nor specific active ingredients and their concentrations appeared to predict the duration of efficacy we observed for the 25(b) exempt products. These products are not registered with the EPA, so the methods used to determine the application guidelines on their labels are unclear. Consumers should be aware that both the level of efficacy and the duration of repellency may differ among unregulated 25(b) exempt repellent products labeled for use against ticks. We encourage more research on these products and the 25(b) exempt active ingredients they contain to help determine and improve their efficacy as repellents under different conditions.
美国大多数虫媒病病例是由蜱传播的病原体引起的，最常见的是黑腿蜱，Ixodes scapularis。 个人防止蜱叮咬，包括使用驱虫剂，是预防蜱传疾病的主要措施。 美国环保署（EPA）注册的蜱虫驱虫剂被证明是安全有效的，能有效对抗蜱虫。 另一组蜱虫驱虫剂产品，25(b)豁免或低风险产品，使用替代的，主要是植物衍生的，活性成分。 这些产品被认为对人类健康的风险最小，因此免于 EPA 注册；这些产品不需要进行功效测试。
我们使用手指生物测定法评估 11 种配方的 25(b)豁免产品对 I. scapularis 若虫的驱避效果，以及两种阳性对照的基于 DEET 的 EPA 注册产品。 在产品使用后 0.5 至 6.5 小时，每小时评估一次驱避效果。
基于 DEET 的产品在所有检查时间点均表现出≥97%的驱避率。 相比之下，在 11 种 25(b)豁免产品应用后 1.5 小时内，平均有 63%的蜱虫被驱避，而在 2.5 至 6.5 小时之间，平均被驱避率降至 3%。 在应用后 30 分钟，11 种 25(b)豁免产品中有 10 种与基于 DEET 的产品表现出相似的功效（驱避率为 79-97%）。 然而，只有 4 种 25(b)豁免产品在 1.5 小时标记时仍能保持与基于 DEET 的产品相似的驱避效果（>72%），并且这些产品在应用后 2.5 至 6.5 小时的时间点均无法有效驱避蜱虫。
标签上的声明以及特定的活性成分及其浓度似乎都无法预测我们观察到的 25(b)豁免产品的功效持续时间。 这些产品未在美国环保署注册，因此其标签上确定应用指南所使用的方法尚不清楚。 消费者应该注意到，未受监管的 25(b)豁免驱虫剂产品在标签上标明可用于防治蜱虫，其功效水平和驱避持续时间可能有所不同。 我们鼓励对这些产品及其所含的 25(b)豁免活性成分进行更多研究，以帮助确定并改善它们在不同条件下作为驱避剂的功效。
