An Agent-Based Model of Biting Midge Dynamics to Understand Bluetongue Outbreaks

Bluetongue (BT) is a well-known vector-borne disease that infects ruminants such as sheep, cattle, and deer with high mortality rates. Recent outbreaks in Europe highlight the importance of understanding vector-host dynamics and potential courses of action to mitigate the damage that can be done by BT. We present an agent-based model, entitled 'MidgePy', that focuses on the movement of individual Culicoides spp. biting midges and their interactions with ruminants to understand their role as vectors in BT outbreaks, especially in regions that do not regularly experience outbreaks. The results of our sensitivity analysis suggest that midge survival rate has a significant impact on the probability of a BTV outbreak as well as its severity. Using midge flight activity as a proxy for temperature, we found that an increase in environmental temperature corresponded with an increased probability of outbreak after identifying parameter regions where outbreaks are more likely to occur. This suggests that future methods to control BT spread could combine large-scale vaccination programs with biting midge population control measures such as the use of pesticides. Spatial heterogeneity in the environment is also explored to give insight on optimal farm layouts to reduce the potential for BT outbreaks.

Automated summary

Bluetongue (BT), a vector-borne disease with high mortality rates, infects ruminants and recent outbreaks in Europe emphasize the need to understand vector-host dynamics and potential mitigation strategies. We present an agent-based model, 'MidgePy', which focuses on the movement of Culicoides spp. midges and their interactions with ruminants to study their role as vectors, especially in non-outbreak regions. Sensitivity analysis shows that midge survival rate significantly affects the probability and severity of BT outbreaks. By using midge flight activity as a proxy for temperature, we find a correlation between environmental temperature and outbreak probability, suggesting combining vaccination programs with midge population control measures. The study also explores spatial heterogeneity to inform optimal farm layouts for reducing BT outbreaks.