Route of Infection Affects Pathogenicity of Leishmania major in BALB/c Mice

Introduction: The term Leishmaniasis applies to a group of parasitic diseases caused by the genus Leishmania. Route of infection is one of the variables that have been reported to influence the immune responses as well as the disease outcome in experimental models of leishmaniasis. This research aims to study the effect of route of infection on the pathogenicity of Leishmania major in BALB/c mice. Methods: Low (103 parasites/mouse) and high (106 parasites/mouse) doses of L. major was injected into footpad or ear dermis of BALB/c mice. Lesion diameter was determined throughout the study. Parasite load of draining lymph nodes and spleen were assessed at three intervals. Results: Footpad in comparison to ear route showed higher pathogenicity of L. major in BALB/c mice as assessed by lesion diameter, parasite load in the draining lymph node, and dissemination of the parasite to the spleen. Conclusion: Our findings suggest that substantial differences between footpad and ear route need particular attention when we use experimental models for the study of Leishmania infections.