Verification and monitoring of visceral leishmaniasis in hamsters caused by Leishmania infantum, using non-invasive approaches involving ultrasound imaging and blood gases

Hamsters are a suitable experimental model for visceral leishmaniasis (VL) because they mimic the features of the human disease. However, the infection after inoculation can only be verified after sacrifice of the animal or several months following infection, when obvious signs of the disease appear, compromising animal welfare in both cases. Unlike other studies, the present work used an inoculum of 5 × 108 promastigotes to induce Leishmania infantum infection, which are easier to produce than amastigotes, in in vitro culture. The infection in hamsters was detected using non-invasive methods such as ultrasound imaging (USG) and blood gases, in addition to alterations in hematological parameters and weight loss. USG imaging identified changes in the size and echogenicity of the spleen, liver, and kidney as early as week 9 (W9) after experimental inoculation. However, blood gases, specially lactate, was increased in response to the infection, with statistically significant differences between W9 and W0 (before infection) (p