Aspectos morfol?gicos, biol?gicos e epizootiol?gicos de Parahaemoproteus nettionis (JOHNSTON & CLELAND, 1909) (HAEMOSPORIDIIDEA: HAEMOPROTEIDAE) em Cairina moschata L. no Brasil

• Author(s): Yamamura, Milton Hissashi
• Date: 2020
• Origin: Oasisbr
• Subject(s): Medicina Veterin?ria; Medicina Veterin?ria
• Document Type: Master thesis
• Language: Portuguese

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Coordena??o e Aperfei?oamento de Pessoal de N?vel Superior - CAPES

Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq

Infections of Parahaemoproteus nettionis (Johnston & Cleland, 1909), recorded on the basis of the presence of mature gametocytes, were encountered only in Cairina moschata of more than 40 days old. The occurrence of this parasite was recorded in the State of Rio de Janeiro, the State of S?o 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. Biological tests under experimental conditions showed that Culex fatigans is not an efficient transmittor. Due to the poor survival of simulids and ceratopogonids in the laboratory and to the difficulty of proving the feeding of these dipterans on C. moschata, it was not possible to demonstrate the development of P. nettionis in these probable vectors. 77 In the erythrocytes of the host only sexual forms of the parasite were observed. Inoculations of blood, or of suspensions of macerated organs from birds known to be parasitised, were inadequated for the transmission of the parasite. The exflagellation of the microgametocytes of P. nettionis could 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 show 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 examined, and with frequent polyparasitism, there were no signs of anaemia or mortality. Inoculations of cortisone, splenectomy, or a combination of both, are ineffective as methods of aggravating the pathogenicity of P. nettionis.

O parasitismo por Parahaemoproteus nettionis (Johnston & Cleland, 1909) foi constatado pela presen?a de gamet?citos maturos somente em Cairina moschata com mais de 40 dias de idade. Verificou-se sua ocorr?ncia em aves nos Estados do Rio de Janeiro e de S?o Paulo e do Territ?rio Federal de Roraima, calculando-se a preval?ncia de 22,4% para toda amostra trabalhada. Os maiores ?ndices de preval?ncia foram observados nos meses de mar?o e abril, per?odo que corresponde ? fase final da maior quantidade de insetos hemat?fagos nas ?reas ditas enzo?ticas do parasito. Os testes biol?gicos em condi??es experimentais mostraram que Culex fatigans n?o se constitui em um transmissor adequado. Em face das prec?rias condi??es de sobreviv?ncia de simul?deos e ceratopogon?deos em laborat?rio e da dificuldade de comprovar o hematofagismo destes d?pteros em C. moschata, n?o foi poss?vel demonstrar o desenvolvimento de P. nettionis nestes prov?veis vetores. Nos eritr?citos dos hospedeiros, somente as formas sexuadas do parasito foram observadas. As inocula??es de sangue e de suspens?o de macerados de ?rg?os de aves comprovadamente parasitadas n?o se constitu?ram em meio adequado de transmiss?o desta parasitose. A exflagela??o de microgamet?citos de P. nettionis foi pass?vel de observa??o a partir de dois minutos e trinta segundos, ap?s a pun??o para coleta de sangue, com emiss?es de at? oito microgametas. Evidenciou-se que P. nettionis ? pouco patog?nico para C. moschata, pois as formas sexuadas encontradas nos eritr?citos determinam o aumento de tamanho da c?lula parasitada e frequentemente deslocam o n?cleo delas. Tamb?m se demonstrou que o grau de parasitemia de aves infectadas em condi??es naturais geralmente ? baixo; mesmo em casos de ?ndices superiores a 100 eritr?citos parasitados/10.000 examinados e frequente poliparasitismo, n?o foram observados sinais de anemia, nem mortalidade. As inocula??es de cortisona, a esplenectomia e a associa??o destes dois m?todos n?o constitu?ram em meios adequados para exacerbar a patogenicidade de P. nettionis.