Impiego della Spettroscopia Raman nella diagnosi di leishmaniosi canina

Leishmaniasis is a zoonosis of world interest, and one of the most important agent is L. infantum. Dogs are the principal reservoirs affected by a broad spectrum of clinical features. In the view of a more rapid and less expensive diagnosis of leishmaniasis, Raman spectroscopy, a rapid qualitative and quantitative technique that allows the simultaneous determination of several components in the biological fluids, was applied on the serum of not affected and affected dogs. Thirty-three dogs were divided into three groups based on their serological test for leishmaniasis (IFAT) and clinical status: Leishmania group (LG), constituted by 18 seropositive ill dogs; asymptomatic group (AG), constituted by 2 seropositive asymptomatic dogs; control group (CG), constituted by 14 healthy seronegative dogs. Blood samples were collected in tubes without anticoagulant during clinical exams. One aliquot was subjected to the Raman spectroscopic analysis. The acquired spectra, obtained from sera of LG and CG subjects were different in the region 1,200-1,370 cm-1, in which it is possible to distinguish the amide III vibration (1,300 cm-1). In LG an evident shift to the shortwave region is observed in spectral frequencies of the band centered at 1,250 cm-1, corresponding to leucine and isoleucine. In AG, spectra were like the control group. In AG spectra were like the control group. In 5 dogs affected by leishmaniasis in which it was possible to follow the treatment the spectra were similar to those of healthy animals already after two weeks of therapy. These results were validated by statistical analysis by using the receiver operating characteristic (ROC) curve and the Youden index (Y) to obtain the optimal cut-off point, in order to distinguish between ill group and healthy one, demonstrating the achievability of Raman spectroscopy as rapid and less expensive diagnosis of full-blown leishmaniasis. Further studies are necessary to establish the diagnostic specificity and test reference range.