Improving the knowledge on the distribution and status of the wild populations is desirable to inform strategies for disease surveillance, early detection and control. This is the case for the red fox in North-Eastern Italy, where rabies has been eradicated after a recent epizootic but the risk of its re-introduction through the eastern border is still acknowledged. Nevertheless, the systematic collection of data concerning fox distribution and dynamics remains difficult for many reasons, among which the very limited interest for this species and the land use changes. Since specific research performed by trained personnel, needed for providing accurate estimates of the population size and density, implies high expenses and can be maintained only for limited periods of time in small sample areas, a possible option is to exploit methods as cost-effective as possible, with the aim of a continuous monitoring at least of the fox population trend in time. For this aim, in this paper we explore the use of the spring night censuses for the red deer as a tool for the systematic collection of fox counts. This five-year study was carried out in the alpine province of Belluno, along the course of two subsequent epizootics in the fox population: the first caused by rabies and the second by canine distemper. The fox relative abundance (in terms of index ok kilometric abundance - IKA) was examined in the light of the consecutive presence of these two viral diseases by the passive disease surveillance data, in order to approach the use of spring night counts in detecting significant variations in the fox population size. The method herein proposed appears promising in the detection of these variations, such as those caused by severe epizootics, and further investigation aimed at its validation is worthwhile for both informing passive surveillance on disease and research in fox ecology.