Diversity and distribution of avian malaria and related haemosporidian parasites in captive birds from a Brazilian megalopolis

Abstract

Background: The role of zoos in conservation programmes has increased significantly in last decades, and the health of captive animals is essential to guarantee success of such programmes. However, zoo birds suffer from parasitic infections, which often are caused by malaria parasites and related haemosporidians. Studies determining the occurrence and diversity of these parasites, aiming better understanding infection influence on fitness of captive birds, are limited.

Methods: In 2011-2015, the prevalence and diversity of Plasmodium spp. and Haemoproteus spp. was examined in blood samples of 677 captive birds from the São Paulo Zoo, the largest zoo in Latin America. Molecular and microscopic diagnostic methods were used in parallel to detect and identify these infections.

Results: The overall prevalence of haemosporidians was 12.6%. Parasites were mostly detected by the molecular diagnosis, indicating that many birds harbour subclinical or abortive infections. In this project, birds of 17 orders (almost half of all the orders currently accepted in taxonomy of birds), 29 families, and 122 species, were tested, detecting positive individuals in 27% of bird species. Birds from the Anatidae were the most prevalently infected (64.7% of all infected animals). In all, infections with parasites of the genus Plasmodium (overall prevalence 97.6%) predominated when compared to those of the genus Haemoproteus (2.4%). In total, 14 cytochrome b (cytb) lineages of Plasmodium spp. and 2 cytb lineages of Haemoproteus spp. were recorded. Eight lineages were new. One of the reported lineages was broad generalist while others were reported in single or a few species of birds. Molecular characterization of Haemoproteus ortalidum was developed.

Conclusion: This study shows that many species of birds are at risk in captivity. It is difficult to stop haemosporidian parasite transmission in zoos, but is possible to reduce the infection rate by treating the infected animals or/and while keeping them in facilities free from mosquitoes. Protocols of quarantine should be implemented whenever an animal is transferred between bird maintaining institutions. This is the first survey of haemosporidians in captive birds from different orders maintained in zoos. It is worth emphasizing the necessity of applying practices to control these parasites in management and husbandry of animals in captivity.

Keywords: Avian malaria; Captive birds; Conservation; Haemoproteus; Plasmodium; Zoo.

Fig. 1

Population studied. Orders of examined birds are presented in decreasing direction of abundance, and they were categorized in highly abundant, moderately abundant, and rare. Exact numbers of all examined species are given in Table 1 and Table S1. The ordinate shows the relative order abundance (in percentage)

Fig. 2

Overall prevalence of Plasmodium and Haemoproteus infections in birds from São Paulo Zoo in different seasons. Total number of examined birds (n) was 677. Data for all years were combined. The ordinate is the prevalence of infection (in percentage). Vertical lines are 95% confidence limits

Fig. 3

Plasmodium and Haemoproteus parasite lineage diversity (in percentage) in relation to the total number of detected lineages. Red font indicates new lineages. Haemoproteus lineages are boxed

Fig. 4

Bayesian phylogeny of cytochrome b gene lineages of avian Plasmodium species. Lineages recorded in this work are given in Bold. Codes of the lineages are given after species names of parasites, and GenBank accession numbers are provided before the parasite species names. Nodal support values (in percentage) indicate posterior clade probabilities

Fig. 5

Bayesian phylogeny of cytochrome b gene lineages of Haemoproteus species. Lineages recorded in this work are given in Bold. Codes of the lineages are given after the species names of parasites, and GenBank accession numbers are provided before the parasite species names. Nodal support values (in percentage) indicate posterior clade probabilities. Vertical bars indicate clades of species of subgenus Haemoproteus (a) and Parahaemoproteus (b)

Fig. 6

Blood stages of four Plasmodium spp. found in this study. The lineage pDENVID01 (a–d): note small meronts possessing a retractable globule (a), growing meronts possessing outgrowth (b) and mature macrogametocytes (c) and microgametocytes (d) with amoeboid outline; microgametocytes possess big haemozoin pigment granules. The lineage pRAMVIT01 (e–h): note small meronts and retractable globules (e, f), and gametocytes usually found in polar and subpolar position in infected cell and possessing distinct prominent nuclei (g, h). The lineage pSALAT01 (i–l): it was identified by phylogenetic analysis as a Novyella lineage, but the infected host had mixed infection with another Plasmodium lineage; small meronts (i), a feature of Novyella subgenus and growing meronts (j) and gametocytes (k, l) with Haemamoeba morphological characteristics. The lineage pNYCNYC01 (m–p): phylogenetic analysis has identified it a lineage of Haemamoeba subgenus; it has meronts with prominent cytoplasm and they displace the nucleus of infected erythrocytes (m–o), the same characteristic can be seen in mature microgametocytes (p). Scale bar 10 µm. Triangle merozoites. Long arrow parasite nuclei. Small arrow haemozoin pigment. Arrow head merozoite

Fig. 7

Gametocytes of Haemoproteus (Parahaemoproteus) ortalidum (lineage hPENOBS01, GenBank KX171627) from the blood of Dusky-legged guan (Penelope obscura). Note the elongate macrogametocyte (a) possessing a large round vacuole, which might reach 3 μm in diameter, roundish young microgametocytes (b) and elongate mature microgametocytes (c, d). Arrow vacuole. Scale bar 10 µm. Long arrow parasite nuclei. Arrow head vacuole. Small arrow haemozoin pigment

Fig. 8

Median-joining network of a worldwide collection of Plasmodium (Haemamoeba) parasite cytb haplotypes. Circles represent haplotypes, and their sizes are proportional to haplotype frequencies. Colours indicate the host order (a) or region of origin of the samples (b). Each line connecting the circles represents a mutational step

Fig. 9

Lineage diversity (in percentage) of reported parasites by birds of different orders. The ordinate shows percentage