Detecção de circovirus dos psitacideos em aves silvestres em cativeiro no Brasil

Abstract

This study determined the occurrence of Beak and Feather Disease virus (Circovirus parrot) in birds kept under human care in commercial aviaries in Minas Gerais (n=137) and Espírito Santo (n=25), live animal markets in Belo Horizonte (n=209), pet birds cared for in Minas Gerais (n=60) and Espírito Santo (n=7), and free-ranging birds under treatment at a university center in Belo Horizonte (n=3). Detection of the Circovirus parrot (PsCV/Circovirus parrot) genome was performed by PCR using previously described oligonucleotides. A total of 475 birds were tested, 428 Psittaciformes and 47 from other orders (Passeriformes, Columbiformes, Strigiformes, Galliformes and Musophagiformes), from blood (n=354), feathers (n=386), cloacal swabs (n=262) and other tissues (n=9), with birds tested in more than one sample. Circovirus parrot was detected in 193 (40.6%) birds, including non-Psittaciformes species, such as Tauraco persa (n=2), Athene cunicularia (n=1), Geopelia cuneata (n=1), Serinus canaria (n=7), Columba livia (n=7) and Zenaida auriculata (n=5). These were positive in feathers and/or cloacal swabs, except for one T. persa, also positive in blood. The incidence of PsCV varied among Psittaciformes groups, reaching 38% to 80% in commercial aviaries, 43% in live animal markets and 20% in companion birds. Among birds belonging to non-Psittaciformes orders, the incidence was 48%. These values are higher than those reported in captive birds in Italy (8.05%) and relatively close to those observed in Psittaciformes in Namibia (24.48%). However, they remain lower than the rates recorded in free-ranging Cacatua galerita in Australia (70.3%). Although predominant in exotic species (92.7%), the virus has been identified in native psittacines kept as pets (Ara ararauna, Psittacara leucophthalmus, Guaruba guarouba, Amazona aestiva and Anodorhynchus hyacinthinus). Most of the positive psittacines in live bird markets did not present evident clinical signs (87.7%), highlighting the potential for silent spread of the virus. Four birds were necropsied, with skin collection and histopathological examination; however, no lesions characteristic of Circovirus parrot were observed. Phylogenetic analysis of 50 sequenced samples revealed sequences with unique identity to Circovirus parrot, with related strains in five distinct groups and one non-clustered strain, with high similarity to the region of the gene encoding VP1 of international strains. The findings suggest greater proximity between the Brazilian sequences, indicating possible phylogenetic evolution of PsCV in Brazil. Occurrence rates in exotic birds were higher than those previously described in the country. The increased occurrence of the virus may be associated with the growing demand for pet birds (PET), which drives the expansion and, at times, overcrowding of commercial flocks. This scenario favors failures in biosecurity measures, facilitating the spread of the agent, especially given the possibility of commercializing birds with subclinical infections, due to the difficulties in early identification of infected birds and silently contributing to the maintenance and spread of the virus among flocks and the PET market. The lack of specific national legislation or guidelines for controlling Circovirus parrot aggravates the problem, limiting control to isolated initiatives by professionals and institutions. Under current conditions, euthanasia is still the only effective way to contain outbreaks, but it faces resistance from guardians and breeders, making health control difficult and favoring the maintenance of the virus throughout the commercial chain.