Introduction: Leishmania major needs a sensitive and specific method for proper diagnosis. This study aims to study the course and histopathology of L. major in certain tissues of experimentally infected BALB/c mice after subcutaneous (sc) and intraperitoneal (ip) inoculation.
Materials and methods: After infecting BALB/c mice using sc and ip inoculation, the histopathology was studied. The kinetoplastic DNA polymerase chain reaction (PCR) for its molecular detection and detect the inducible nitric-oxide synthase (iNOS) pattern during the first 3 months of infection.
Result: PCR could detect the presence of L. major in all spleens, lymph nodes, and skin ulcers by both inoculation routes while (33%) and (42%) of livers were positive after sc and ip routes, respectively. Chronic inflammatory cell infiltrates with capsulitis was found in the spleen, lymph nodes, and liver. Granulomas were found in the spleen and liver. There was a statistically significant difference in iNOS expression along the experiment in the spleen and lymph nodes by both routes and in the liver by ip only. Apart from the liver, iNOS could not be detected on the 2(nd) week postinfection and was high after 1 month for both routes in all samples; a moderate decrease at 2 months and the highest decrease were detected after 3 months.
Conclusions: L. major inoculation by both routes produce visceral disease in mice, and kinetoplastic DNA PCR can detect its presence from the 2(nd) week up to the 3(rd) month postinfection. The iNOS expression was high at 1 and 2 months and remained throughout the 3 months of the experiment; which plays an important role in the disease course and control.
Keywords: Inducible nitric-oxide synthase; Leishmania major; intraperitoneal routes; kinetoplastic DNA polymerase chain reaction; subcutaneous.