Experimental Toxoplasmosis in Pigeons (Columba livia)

Abstract

The purpose of the present study was to establish experimental model of toxoplasmosis in pigeons, to investigate pathogenesis and compare tissue lesions by clinical, histopathological, serological and bioassay techniques. Total of 60 unknown aged pigeons (Columba livia), 21 males and 39 females were used. They were divided into groups as oral (Group I and II) and parenteral (Group III, IV, V and VI) infection groups (Table 1). While some pigeons in Group IV showed acute infection signs such as anorexia, weight loss, pale cockscomb, bend of head and neck and partial paralyze; chronic infection signs such as anorexia, weakness, weight loss, diarrhea, difficulties in breathing, and conjunctivitis were seen in Group IV, V, and VI. In necropsy, the pigeons in Group IV had hyperemia and focal hemorrhages in the meninges and brain; the pigeons in Groups V and VI had yellowish color of the liver, the pigeons in Group V had the pale chest muscles, pericardial thickening and opaqueness. There were no macroscopic findings in pigeons in Group I and III. Histopathological examination revealed nonsuppurative meningoencephalitis and tachyzoites and bradyzoite cysts formation of T. gondii in brain tissue, lymphoid cell infiltration and necrotic focal hepatitis and nephritis in Group IV. While pigeons in Group V had nonsuppurative focal myositis, myocarditis, hepatitis, gastritis, enteritis, pneumonitis, and necrotic pancreatitis, one of them had toxoplasma bradyzoite cyst in the sinusoid in the liver. In group VI, nonsuppurative focal hepatitis, myocarditis, nephritis and necrotic pancreatitis were detected in pigeons. Bioassay tests were performed with tissue samples taken from seropositive pigeons and parasitic tachyzoites were isolated from the peritoneal fluid of the mice. Seropositivity in the oral and parenteral groups was determined by Sabin-Feldman Dye Test (SFDT) and Indirect Hemagglutination Assay (IHA). As a result; in similar studies that will be performed investigating pathogenesis of Toxoplasmosis and subclinical cases that may be overlooked, serologic tests and bioassay applications should be used together for the diagnosis of toxoplasmosis.