Abundance thresholds are of fundamental importance in our attempts to understand the dynamics of wildlife infection. Identifying and manipulating these thresholds may also have substantial applied significance. The plague system in the Pre-Balkhash region of Kazakhstan has been extensively studied, including an unusually thorough investigation of the nature and importance of an abundance threshold for the infection. Great gerbils are the main reservoir host, with plague transmitted between them by a variety of flea species. Initial work identified such a threshold from time-series data, with great gerbil abundance being measured by level of occupancy (the proportion of the burrow systems in the landscape supporting an extended family group). However, this and other refinements of the threshold were better at predicting the absence of plague (below the threshold) than in guaranteeing its presence (above). Further analysis indicated that the threshold was a critical point in the percolation of plague across the landscape, rather than in a mass-action random mixing process. The performance of the threshold was also improved by incorporating both gerbil and flea abundance to generate a hyperbolic threshold curve.