HEMATOLOGIC CHARACTERISTICS OF AVIAN MALARIA CASES IN AFRICAN BLACK-FOOTED PENGUINS (SPHENISCUS-DEMERSUS) DURING THE FIRST OUTDOOR EXPOSURESEASON

Twenty-nine juvenile, captive-reared African black-footed penguins (Sp heniscus demersus) were hematologically monitored every 2 wk over the period of 24 wk during their first outdoor exposure. Blood samples tak en from the penguins were screened for 12 blood evaluation parameters. Parasitemic penguins were medically treated. Eighteen birds (62.1%) e xperienced naturally acquired malaria and 11 birds (37.9%) remained no nparasitemic. A total of 32 avian malaria episodes were noted; 25 (78. 1%) were identified as Plasmodium elongatum. 5 (15.6%) as Plasmodium r elictum, and 2 (6.3%) as Plasmodium spp. One P. elongatum (3.4%) and 3 P. relictum (10.3%) infections were fatal. All deaths occurred during the first episode of parasitemia. Gross lesions of the birds that die d included hepatomegaly and splenomegaly. Interstitial pneumonia with schizonts was observed on histological examinations. The range, mean, and SD of 12 hematological parameters were determined for nonparasitem ic and parasitemic penguins. Differences between these groups in total white blood cell (WBC) counts and relative lymphocytosis (LYMPHS) wer e not significant. The combined classes of total WBC counts(>20.0 x 10 (3)/mu l) and LYMPHS (>60.0%) are not indicative of avian malaria infe ction in African penguins. No correlations were found between changes in the values of blood parameters with season or age of penguins. Trea tment of parasitemic birds significantly reduced expected mortality fr om 50.0% to 13.8%.