Experimental visceral leishmaniasis in the owl monkey

Area of Science:

• Parasitology
• Immunology
• Primate Models

Background:

• Visceral leishmaniasis (VL) is a severe parasitic disease.
• Leishmania donovani causes VL, primarily affecting the spleen, liver, and bone marrow.
• Effective animal models are crucial for understanding VL pathogenesis and developing treatments.

Purpose of the Study:

• To evaluate the susceptibility of owl monkeys (Aotus trivirgatus) to Leishmania donovani infection.
• To characterize the clinical, hematological, and immunological responses in infected owl monkeys.
• To assess the suitability of the owl monkey as an animal model for VL.

Main Methods:

• Intravenous inoculation of eight owl monkeys with Leishmania donovani (Khartoum strain).
• Clinical monitoring for signs of disease, including weight loss, anemia, and organomegaly.
• Hematological and serum biochemical analyses.
• Immunological assessment of antibody titers and immunoglobulin levels.
• Histopathological examination of infected organs for parasite burden.

Main Results:

• All eight owl monkeys developed visceral leishmaniasis.
• Six monkeys succumbed to the infection within 93 days; two recovered.
• Clinical signs included significant weight loss, anemia, and hepatosplenomegaly.
• Hematological abnormalities comprised anemia, granulocytopenia, thrombocytopenia, and lymphocytosis.
• Biochemical analyses revealed hyperbilirubinemia, azotemia, hyperglobulinemia, hypoalbuminemia, and altered hemostasis.
• Positive antibody titers to L. donovani and increased IgM and IgG levels were observed.
• Macrophages in the liver, spleen, bone marrow, and lymph nodes were heavily parasitized.

Conclusions:

• Owl monkeys exhibit high susceptibility to Leishmania donovani infection.
• The observed clinical and pathological manifestations closely resemble human visceral leishmaniasis.
• The owl monkey serves as a valuable and relevant animal model for studying visceral leishmaniasis.