Leishmania infantum and Neospora caninum simultaneous skin infection in a young dog in Italy

Leishmania infantum, the agent of canine leishmaniasis in Mediterranean cou ntries, and Neospora caninum, a recently recognized protozoal pathogen in d ogs, were diagnosed in a 9-month-old Argentine Dogo dog. Both skin lesions and neurological signs were present. Histopathology of cutaneous lesions re vealed a suppurative, diffuse dermatitis with numerous intracellular protoz oa. Serology was positive for both L. infantum (1:640) and N. caninum (1:80 0). Double-label immunohistochemical staining of skin samples with hyperimm une serum from L. infantum-infected dogs was positive for protozoa within m acrophages, while the polyclonal antibody specific for N. caninum showed po sitive reactions for protozoa in endothelial cells and fibroblasts. Transmi ssion electron microscopy (TEM) confirmed the infection with both protozoa. This is, to the authors' knowledge, the first case of simultaneous infecti on with L. infantum and N. caninum in a dog. It is possible that the immuno suppressive effects of Leishmania infection or long-term steroid therapy ma y have been a contributing factor to the development of N. caninum in this dog. (C) 2001 Elsevier Science B.V. All rights reserved.