Aspectos morfológicos de Parahaemoproteus nettionis (JOHNSTON & CLELAND, 1909) (haemosporidiidea: haemoproteidae) em Cairina moschata L. no Brasil

Abstract

Infections of Parahaemoproteus nettionis (Johnston & Cleland, 1909) recorded on the basis of the presence of mature ga-metocytes, were encountered only in Cairina moschata of more than 40 days age. The occurrence of this parasite was recorded in the States of Rio de Janeiro, São Paulo and in the Federal Territory of Roraima, with a calculated prevalence of 22,4% for all material examined. The highest indices of occurrence were observed in March and April, the period corresponding with the final phase of the population peak of blood-sucking insects in the enzootic areas. In the erythrocytes of the host only sexual forms of the parasite were observed. The exflagellation of the microgametocytes of P. nettionis were be observed after two minutes and thirty seconds, with emissions of up to eight microgametes. It was noted that P. nettionis is hardly Pathogenic for C. moschata although the sexual forms encountered in the erythrocytes cause an increase in the size of the parasitised cell, frequently displacing their nuclei. Additionally, it was shown that the degree of parasitaemia in naturally infected birds is low; even in those cases with an index above 100 erythrocytes parasitised per 10,000 examinad, and with frequent polyparasitism, there were no signs of anaemia or mortality.