Fatal toxoplasmosis in free-ranging endangered 'Alala from Hawaii

The 'Alala (Corvus hawaiiensis) is the most endangered corvid in the world, and intensive efforts are being made to reintroduce it to its former nativ e range in Hawaii. We diagnosed Toxoplasma gondii infection in five free-ra nging 'Alala. One 'Alala, recaptured from the wild because it was underweig ht and depressed, was treated with diclazuril (10 mg/kg) orally for 10 days . Antibodies were measured before and after treatment by the modified agglu tination test (MAT) using whole T. gondii tachyzoites fixed in formalin and mercaptoethanol. The MAT titer decreased four-fold from an initial titer o f 1:1,600 with remarkable improvement in physical condition. Lesions of tox oplasmosis also were seen in two partially scavenged carcasses and in a thi rd fresh intact carcass. Toxoplasma gondii was confirmed immunohistochemica lly by using anti- T. gondii specific serum. The organism was also cultured by bioassay in mice from tissues of one of these birds and the brain of a fifth 'Alala that did not exhibit lesions. The life cycle of the parasite w as experimentally completed in cats. This is the first record of toxoplasmo sis in 'Alala, and the parasite appears to pose a significant threat and ma nagement challenge to reintroduction programs for 'Alala in Hawaii.