Experimental toxoplasmosis in Japanese quail

Area of Science:

• Veterinary Parasitology
• Avian Pathology
• Immunology

Background:

• Toxoplasma gondii is an important protozoan parasite with a wide host range.
• Avian species can serve as reservoirs or intermediate hosts for T. gondii.
• Understanding T. gondii pathogenesis in quail is crucial for food safety and disease control.

Purpose of the Study:

• To investigate the pathogenicity and immune response of Japanese quail (Coturnix japonica) experimentally infected with different strains and doses of Toxoplasma gondii.

Main Methods:

• Twenty-four 5-month-old Japanese quail were orally inoculated with varying doses (10^3 and 10^5 oocysts) of ME 49 and GT-1 strains of T. gondii.
• Birds were monitored for mortality, and survivors were euthanized at 63 days post-inoculation (DAI).
• T. gondii isolation, histopathological examination of tissues (brain, heart, skeletal muscle, spleen, intestine), and serological tests (modified agglutination, indirect hemagglutination, latex agglutination, Sabin-Feldman dye test) were performed.

Main Results:

• High mortality rates were observed, particularly in birds inoculated with the GT-1 strain, with deaths occurring within 8-23 DAI.
• Survivors (examined at 63 DAI) had T. gondii isolated from brain, heart, and skeletal muscle.
• Histopathology revealed severe lesions including pneumonia, myocarditis, meningoencephalitis, encephalitis, and myositis in affected birds. Survivors exhibited chronic inflammation and splenic changes.
• Antibodies to T. gondii were detected in all survivors by 63 DAI, with the modified agglutination test showing higher titers.

Conclusions:

• Japanese quail are susceptible to T. gondii infection, with significant morbidity and mortality depending on the strain and dose.
• Experimental T. gondii infection can lead to severe systemic disease and chronic pathological changes in quail.
• The modified agglutination test is a sensitive method for detecting T. gondii antibodies in quail.