Acaricide resistance among single-host and multi-host ticks in sub-Saharan Africa: Current status, drivers, and control strategies

Background and Aim: Ticks and tick-borne diseases (TBD) continue to pose a significant threat to livestock production and rural livelihoods in sub-Saharan Africa (SSA). The control of ticks has relied predominantly on the use of chemical acaricides; however, the widespread and often indiscriminate application of these compounds has led to the rapid emergence and spread of acaricide resistance. This review provides a comprehensive synthesis of current knowledge on acaricide resistance in both single-host ticks, such as Rhipicephalus microplus and Rhipicephalus decoloratus, and multi-host ticks, including Amblyomma variegatum and Rhipicephalus appendiculatus, across tropical and subtropical regions of SSA. The evidence indicates that resistance is more pronounced in single-host ticks due to their continuous exposure to acaricides throughout their life cycle, whereas multi-host ticks exhibit emerging resistance patterns influenced by intermittent exposure and ecological adaptability. Multiple resistance mechanisms, including target-site mutations, metabolic detoxification, and behavioral changes, contribute to reduced acaricide efficacy. In addition, environmental factors such as temperature, humidity, vegetation, and climate change play a crucial role in shaping tick distribution, population dynamics, and resistance development. Misuse of acaricides, lack of proper rotation strategies, and limited farmer awareness further accelerate resistance emergence, particularly in smallholder farming systems. The review highlights the urgent need for sustainable and region-specific control strategies. Integrated Tick Management (ITM), combining chemical rotation, biological control agents, pasture and habitat management, and farmer education, offers a promising approach to mitigate resistance and improve tick control outcomes. However, gaps remain in understanding resistance patterns in multi-host ticks and wildlife reservoirs, as well as in the implementation of coordinated surveillance programs. Strengthening research, improving stakeholder collaboration, and enhancing farmer training are essential to ensure the long term effectiveness of tick control strategies and to safeguard livestock productivity in SSA.