Comparative analyses of coproscopical techniques to diagnose enteroparasites in a group of captive Indian peafowl (Pavo cristatus)

Captive animals commonly have infections by direct life cycle parasites, since they are easily transmitted between individuals. However, diagnosing these infections in the laboratory is challenging due to the wide variety of parasite, their life stages and to the variety of available diagnose techniques, being difficult to choose the best one. The present study sampled a group of captive Indian peafowl (Pavo cristatus) from Sao Paulo Zoological Park Foundation, Sao Paulo, Brazil, to test and compare different coproscopical techniques commonly applied in veterinarian clinical analysis laboratories: direct smear, concentrations by sodium chlorite, sucrose, zinc sulphate, faecal sedimentation and formalin-ether followed by modified Ziehl-Neelsen staining. Sensitivity, specificity, predictive values (positive and negative) and Cohen’s kappa index were calculated. In total 108 samples were processed and parasites found were: nonsporulated coccidian oocysts (91.7%), Capillarinae eggs (89.8%), unidentified nematode larvae (75%), Ascarididae eggs (63%), unidentified nematode adults (60.2%), unidentified nematode eggs (42.6%), strongylid-like eggs (42.6%), Cryptosporidium spp. (28.7%), flagellated (15.7%) and ciliated (10.2%) protozoans, trematode eggs (0.9%), Acanthocephala eggs (0.9%), Adeleidae oocysts (0.9%) and Cruzia sp. eggs (0.9%). Sensitivity and specificity varied considerably between parasite groups. Cohen’s Kappa index reinforces the recommendation of applying more than one technique to diagnose enteroparasites infections.

Plasmodium (Novyella) nucleophilum from an Egyptian Goose in São Paulo Zoo, Brazil: microscopic confirmation and molecular characterization

Plasmodium (Novyella) nucleophilum was identified using microscopy and PCR, in an Egyptian Goose (Alopochen aegyptiacus) that died in São Paulo Zoo, Brazil. This parasite is characterized by elongated gametocytes, small meronts with scant cytoplasm, less than eight merozoites and mainly for having all the stages appressed to the nuclei of infected erythrocytes. Additionally, Plasmodium (Haemamoeba) sp. was identified by microscopy in the same blood sample. The latter parasite lacks nucleophilic blood stages and is characterized by large roundish trophozoites, each with a large prominent centrally collated vacuole. This co-infection was not confirmed by PCR amplification of the mitochondrial cytochrome b (cytb) gene and sequencing; only one Plasmodium sp. cytb sequence was detected in the blood sample. Since parasitemia of P. nucleophilum (2.4%) was much higher than that of P. (Haemamoeba) sp. (0.2%), PCR may have favored the amplification of the cytb sequence of the former. Phylogenetic analysis is in agreement with this conclusion because the reported cytb sequence was positioned in the same branch of sequences of several Novyella species. This is the first assignment of the mitochondrial cytb gene sequence to P. nucleophilum. The P. (Haemamoeba) parasite is particularly similar to Plasmodium (Haemamoeba) tejerai, because its advanced trophozoites and young erythrocytic meronts possess a large vacuole with prominent pigment granules arranged around it, the characteristic features of development in this species. For definitive identification of P. (Haemamoeba) species, mature meronts and gametocytes are required; however, these were absent from the thin blood smear. Representative images of the blood stages of P. nucleophilum and P. (Haemamoeba) sp. are provided. Together with microscopy data, the P. nucleophilum cytb sequence will assist in molecular identification (barcoding) of this Plasmodium species in other birds.