Pathology of sarcoptic mange in red foxes (Vulpes vulpes): macroscopic and histologic characterization of three disease stages

Sarcoptic mange is a highly contagious skin disease that can have a devastating impact on affected wild mammal populations. There are notable variations in the clinical and pathologic picture of sarcoptic mange among species and among conspecifics. However, the origin of these variations is unclear. We propose a classification scheme for skin lesions associated with Sarcoptes scabiei infestation to provide a basis for a subsequent risk factor analysis. We conducted a case-control study focused on macroscopic and histologic examination of the skin, using 279 red foxes (Vulpes vulpes) found dead or shot in Switzerland between November 2004 and February 2006. All animals were submitted to gross necropsy following a detailed protocol. Selection criteria for cases (n=147) vs. controls (n=111) were the presence or absence of mange-like lesions, mite detection by isolation or histologic examination, and serologic testing for S. scabiei antibodies. Characteristic features of mange lesions were scored macroscopically in all foxes and histologically in 67 cases and 15 controls. We classified skin lesions and associated necropsy findings into three types of mange: A) early stage (n=45): focal-extensive skin lesions, thin crusts, mild to moderate alopecia, few mites, numerous eosinophils, and mild lymph node enlargement; B) hyperkeratotic, fatal form (n=86): generalized skin lesions, thick crusts with or without alopecia, foul odor, abundance of mites, numerous bacteria and yeasts, numerous lymphocytes and mast cells, severe lymph node enlargement, and emaciation; C) alopecic, healing form (n=16): focal lesions, no crusts, severe alopecia, hyperpigmentation and lichenification, absence of mites, mixed cell infiltration, and rare mild lymph node enlargement. We hypothesize that after stage A, the animal either enters stage B and dies, or stage C and survives, depending on largely unknown extrinsic or intrinsic factors affecting the host ability to control mite infestation.

Characterization of the dose distribution in the halo region of a clinical proton pencil beam using emulsion film detectors

Proton therapy is a high precision technique in cancer radiation therapy which allows irradiating the tumor with minimal damage to the surrounding healthy tissues. Pencil beam scanning is the most advanced dose distribution technique and it is based on a variable energy beam of a few millimeters FWHM which is moved to cover the target volume. Due to spurious effects of the accelerator, of dose distribution system and to the unavoidable scattering inside the patient's body, the pencil beam is surrounded by a halo that produces a peripheral dose. To assess this issue, nuclear emulsion films interleaved with tissue equivalent material were used for the first time to characterize the beam in the halo region and to experimentally evaluate the corresponding dose. The high-precision tracking performance of the emulsion films allowed studying the angular distribution of the protons in the halo. Measurements with this technique were performed on the clinical beam of the Gantry1 at the Paul Scherrer Institute. Proton tracks were identified in the emulsion films and the track density was studied at several depths. The corresponding dose was assessed by Monte Carlo simulations and the dose profile was obtained as a function of the distance from the center of the beam spot.