A Novel Method for Determining Efficacy of Acaricides under Field Conditions Using the Relative Risk of Tick Infestation (RRTI)

In Uganda and several other countries, regulatory frameworks mandate that new acaricides undergo field trials prior to registration and licensing. We reviewed the various methods recommended for determining the field efficacy of new acaricides by reputable organizations and methods proposed by scholars. The methods were found to have some shortcomings affecting the quality of the field trial results. These included failure to consider the use of a comparable control product in the control group and failure to meet some principles of epidemiology, good clinical practice and animal welfare. To address these shortcomings and the lack of published literature concerning acaricide field trials, we propose an epidemiologically plausible and comprehensive novel method for determining the efficacy of acaricides under field conditions using the relative risk of tick infestation (RRTI) with the following formula: RRTI =$\frac{at\left(dc+？ac\right)}{ac？\left(dt+at\right)}$ . We also determined the desired outcome for acaricide application, the variable for measurement of the outcome, designed a data capture form for trial data collection, developed formulae for determining efficacy, and provided guidance for interpretation of results as well as decision-making. The method is compliant with the principles of epidemiology, good clinical research practice, and animal welfare and addresses key realities in field settings, thus generating accurate, reliable and credible results. Researchers and regulatory bodies may consider embracing this method to promote the fair and plausible evaluation of new acaricides under field conditions.