National Veterinary Institute, Technical University of Denmark, Copenhagen, Denmark.
Research and Development Department, Danish Meteorological Institute, Copenhagen, Denmark.
Parasit Vectors. 2018 Mar 5;11(1):128. doi: 10.1186/s13071-018-2709-8.
Microclimatic temperatures provide better estimates of vector-borne disease transmission parameters than standard meteorological temperatures, as the microclimate represent the actual temperatures to which the vectors are exposed. The objectives of this study were to quantify farm-level geographic variations and temporal patterns in the extrinsic incubation period (EIP) of Schmallenberg virus transmitted by Culicoides in Denmark through generation of microclimatic temperatures surrounding all Danish cattle farms.
We calculated the hourly microclimatic temperatures at potential vector-resting sites within a 500 m radius of 22,004 Danish cattle farms for the months April to November from 2000 to 2016. We then modeled the daily EIP of Schmallenberg virus at each farm, assuming vectors choose resting sites either randomly or based on temperatures (warmest or coolest available) every hour. The results of the model output are presented as 17-year averages.
The difference between the warmest and coolest microhabitats at the same farm was on average 3.7 °C (5th and 95th percentiles: 1.0 °C to 7.8 °C). The mean EIP of Schmallenberg virus (5th and 95th percentiles) for all cattle farms during spring, summer, and autumn was: 23 (18-33), 14 (12-18) and 51 (48-55) days, respectively, assuming Culicoides select resting sites randomly. These estimated EIP values were considerably shorter than those estimated using standard meteorological temperatures obtained from a numerical weather prediction model for the same periods: 43 (39-52), 21 (17-24) and 57 (55-58) days, respectively. When assuming that vectors actively select the coolest resting sites at a farm, the EIP was 2.3 (range: 1.1 to 4.1) times longer compared to that of the warmest sites at the same farm.
We estimated a wide range of EIP in different microclimatic habitats surrounding Danish cattle farms, stressing the importance of identifying the specific resting sites of vectors when modeling vector-borne disease transmission. We found a large variation in the EIP among different farms, suggesting disease transmission may vary substantially between regions, even within a small country. Our findings could be useful for designing risk-based surveillance, and in the control and prevention of emerging and re-emerging vector-borne diseases.
与标准气象温度相比，微气候温度能更好地估计媒介传播疾病的传播参数，因为微气候代表了媒介实际暴露的温度。本研究的目的是通过生成丹麦所有奶牛场周围的微气候温度，量化 Schmallenberg 病毒通过库蠓传播的农场水平地理变化和外潜伏期（EIP）的时间模式。
我们计算了 2000 年至 2016 年 4 月至 11 月期间，22004 个丹麦奶牛场周围 500 米半径内潜在媒介休息场所的每小时微气候温度。然后，我们假设媒介每小时随机选择休息场所或根据温度（最温暖或最凉爽）选择休息场所，对每个农场的 Schmallenberg 病毒的每日 EIP 进行建模。模型输出的结果以 17 年的平均值呈现。
同一农场最温暖和最凉爽小生境之间的差异平均为 3.7°C（第 5 和第 95 个百分位数：1.0°C 至 7.8°C）。在春季、夏季和秋季，所有奶牛场的 Schmallenberg 病毒平均 EIP（第 5 和第 95 个百分位数）分别为：23（18-33）、14（12-18）和 51（48-55）天，假设库蠓随机选择休息场所。与同一时期从数值天气预测模型获得的标准气象温度估计值相比，这些估计的 EIP 值短得多：43（39-52）、21（17-24）和 57（55-58）天。当假设媒介主动选择农场中最凉爽的休息场所时，EIP 比同一农场最温暖场所长 2.3 倍（范围：1.1 至 4.1）。
我们估计了丹麦奶牛场周围不同微气候生境中广泛的 EIP，强调了在建模媒介传播疾病时确定媒介特定休息场所的重要性。我们发现不同农场之间的 EIP 存在很大差异，这表明即使在一个小国家内，疾病传播也可能在不同地区之间有很大差异。我们的研究结果可能有助于设计基于风险的监测，以及控制和预防新出现和重新出现的媒介传播疾病。
