VIREMIA IN 3 ORDERS OF BIRDS (ANSERIFORMES, GALLIFORMES AND PASSERIFORMES) INOCULATED WITH OCKELBO VIRUS

One-hundred six birds of 14 species were inoculated with approximately 10(2.7) plaque-forming units of Ockelbo virus and bled daily for 5 da ys to determine viremia levels. Virus was detected in birds of all 14 species tested (four Anseriformes, one Galliformes and nine Passerifor mes). The onset of viremia occurred earlier and viral titers were high er in very young anseriforms and galliforms than in older birds. Adult passeriforms had Ockelbo viremias of higher titer and longer duration than did adult anseriforms. Viremia titers in adult birds of all thre e orders tested were sufficient to induce high transmission rates in e nzootic mosquito vectors, and viremias in passeriforms could induce hi gh transmission rates in bridging vectors as well. Passeriforms of the genera Turdus and Fringilla could serve as amplification hosts for Oc kelbo virus based on the presently demonstrated viremia of high titer and long duration in these birds, and the previously demonstrated high prevalence of Ockelbo virus neutralizing antibodies in free-ranging i ndividuals and great population size compared to birds of other taxa. Bird species of all three orders tested, however, could function as in cidental hosts of the virus.