The decision to initiate control efforts against any pest species is normally triggered by an
over-abundance of the pest that is perceived to cause unacceptable impacts on human wellbeing.
In most situations, low to moderate pest populations are considered below an economic
threshold when efforts to reduce pest numbers are deemed impractical, too costly or result in
collateral environmental impacts that cannot be justified. The exception to this principle is
when public health is threatened. This is particularly true in the case of Lyme disease, where the presence of even moderate populations of the blacklegged tick, Ixodes scapularis (formerly Ixodes dammini), poses substantial risk of transmission by virtue of the fact that the degree to which the tick population is infected (infection prevalence) is so high, often exceeding 50%, and exposure to infected ticks occurs most often in residential settings. In such cases, the cost of suppressing pest populations must be weighed against the medical, emotional, and productivity costs associated with the disease. Although a detailed discussion is beyond the scope of this manual, an overview of tick-borne diseases encountered in New Jersey may provide useful insight into the history, complexity, and magnitude of this significant public health problem and may help illustrate the importance of tick control in reducing the risk of disease transmission.