Ten poultry farms (broiler breeder pullets, layer pullets, and broilers) in the provinces of Entre Rios and Buenos Aires in Argentina were examined for presence of Eimeria spp. Litter samples obtained from flocks 7-11 wk old were taken to the laboratory for oocyst counting and sporulation, then concentrated for inoculation into coccidia-free chickens. Species were identified by prepatent period, oocyst size, location and appearance of lesions in the intestine, microscopic examination of mucosal smears, and histology (to confirm Eimeria brunetti). On this basis, Eimeria praecox was found in two samples, Eimeria mitis in two, Eimeria acervulina in nine, Eimeria maxima in seven, Eimeria necatrix in three, Eimeria tenella in seven, and E. brunetti in four. These results confirm the presence of all seven recognized species of Eimeria in chickens in the Republic of Argentina.

In this report, we describe the biological and molecular characterization of a paramyxovirus type-1 (PPMV-1) isolate found in wild pigeons in an urban habitat in Buenos Aires, Argentina. Of the nine pigeons captured, three were moribund, and the other six showed diarrhea, ataxia, tremor, torticolis, and wing paralysis. The intracerebral pathogenicity index was 1.29, and the amino acid (aa) sequence at the fusion protein cleavage site was 112GRQ KRF117. These characteristics correspond to a virulent Newcastle disease virus isolate. Nevertheless, it was not possible to reproduce the disease in chickens experimentally although the chickens exhibited seroconversion after inoculation. On the other hand, pigeons inoculated with the isolate became sick. These results provide further evidence about the unusual pathogenicity of PPMV-1 for chickens and show once more the need for more biological determinations in these cases to arrive at a final conclusion.

Infectious bursal disease is a severe acute viral disease of young chickens, affecting mainly the B-lymphocytes in the bursa of Fabricius, leading to severe immunosuppression as a result of the death of lymphoid cells. In the bursa infected with infectious bursal disease virus, viral replication is associated with apoptosis of lymphoid cells, inflammatory change and atrophy. Vaccination has appeared to be a crucial factor for control, with live attenuated vaccines being the most used. However, the apoptotic effect of these vaccines on the bursa has not been tested. We determined the apoptotic effect caused by the most used vaccines in local production on the bursa of Fabricius cells and the correlation with histological changes. In this study, it was demonstrated that apoptosis levels in the vaccinated groups were higher than those observed in the non-vaccinated birds leading to the conclusion that the action of the live virus vaccine strains modifies the boundary of the bursa and shapes processes of cell death by apoptosis. In contrast to other studies, the vaccine strains used did not show the phenomenon of bursal atrophy during the experimental period.

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