Identification of the avian tracheal trematode Typhlocoelum cucumerinum (Trematoda: Cyclocoelidae) in a host-parasite-environment system: diagnosis, life cycle and molecular phylogeny

Neonatal Care of Anseriformes

Neonatal Anseriformes require specialized care for successful development including access to clean swimming water and food presentation that stimulates natural feeding behavior. Knowledge of natural history is essential for successful rearing. Lightweight and waterproof materials can be used for corrective splinting of many developmental disorders that allow birds to ambulate normally and swim. Captivity-associated lesions can be minimized through proper husbandry and hygiene. Anseriformes are susceptible to a variety of bacterial, viral, fungal, and parasitic diseases, some of which are reportable to state health agencies.

NEW GENUS AND SPECIES OF CYCLOCOELIDAE STOSSICH, 1902 (PLATYHELMINTHES: DIGENEA) INFECTING THE NASOPHARYNGEAL CAVITY OF CANADA GOOSE, BRANTA CANADENSIS (ANSERIFORMES: ANATIDAE) FROM WESTERN ALABAMA

While surveying the parasites of birds associated with western Alabama aquaculture ponds, we collected several specimens of Anativermis normdroneni n. gen., n. sp. (Digenea: Cyclocoelidae) from the nasopharyngeal cavity of a Canada goose, Branta canadensis (Linnaeus, 1758) (Anseriformes: Anatidae). These flukes were heat killed and fixed in neutral buffered formalin for morphology or preserved in 95% ethanol for DNA extraction. Anativermis resembles Morishitium (Witenberg, 1928) by having testes that are spheroid with smooth margins and located in the posterior quarter of the body, an anterior testis that is lateral to the midline and abuts the respective cecum, a posterior testis that is medial (testes diagonal) and abuts the cyclocoel, a genital pore that is immediately postpharyngeal, and a vitellarium that is discontinuous posteriorly. The new genus differs from Morishitium and is unique among all other cyclocoelid genera by having the combination of a body that is broadest in the anterior body half, a posterior body end that is more sharply tapered than the anterior body end, an ovary that nearly abuts the posterior testis, a vitellarium that is asymmetrical and distributes from the area immediately posterior to the cecal bifurcation posteriad to approximately the level of the ovary, and uterine loops extending dorsolateral to the ceca and filling the space between the ceca and the respective body margin for nearly the entire body length. The new genus was recovered as a distinct lineage in separate 28S, 18S, and ITS2 phylogenetic analyses. This is the first report of a cyclocoelid infecting the Canada goose and of a cyclocoelid from Alabama.

Biomphalaria straminea as an Intermediate Host of a Renal Trematode Species of the Genus Tanaisia (Trematoda: Eucotylidae) in Brazil

PURPOSE

Eucotylid trematodes are parasites of the urinary system of birds with a cosmopolitan distribution. Despite the importance of these flukes, fundamental aspects of their biology, such as intermediate hosts and larval morphology, are poorly known. Herein, the potential involvement of aquatic mollusks in the transmission of a species of Tanaisia is reported for the first time.

METHODS

During the search of non-emergent larval stages of trematodes in mollusks collected from an urban waterbody from Brazil in February of 2021, 1 out of 18 specimens (5.5%) of Biomphalaria straminea was found harboring sporocysts, cercariae and encysted metacercariae morphologically compatible with those described for eucotylid species. Sequences generated for 28S, ITS-2, and cox1 molecular markers were compared with sequences available in GenBank and subjected to phylogenetic analyses.

RESULTS

Molecular analyses revealed parasite affiliation with members of the genus Tanaisia, given it groped in a strongly supported clade with species of this genus included in the 28S phylogenetic tree. The larvae tentatively identified as Tanaisia sp. can be conspecific with an unpublished isolate of Tanaisia valida found in birds in South Brazil (100% similarity in 28S and ITS-2).

CONCLUSION

Biomphalaria straminea is reported as a natural host of a species of Tanaisia for the first time. This finding highlights the possibility, so far unknown, of transmission of species of the family Eucotylidae in aquatic environments.

Elucidating the life cycle of opossum parasites: DNA sequences reveal the involvement of planorbid snails as intermediate hosts of Rhopalias spp. (Trematoda: Echinostomatidae) in Brazil

Echinostomatid digeneans belonging to the genus Rhopalias are intestinal trematodes found mainly in opossums in the New World. The genus comprises seven species, but their life cycles and intermediate hosts have been unknown until now. During our long-term study carried out in freshwater habitats within the state of Minas Gerais, Southeast Brazil, echinostomatid cercariae lacking collar spines were found in planorbid snails Biomphalaria glabrata, Biomphalaria straminea, Drepanotrema lucidum and Gundlachia ticaga in six different batches of snail samples collected between 2010 and 2019. Morphologically, the larvae reported herein are morphologically consistent with each other and characterized by the presence of 2-3 large ovoid or spherical corpuscles in each main duct of the excretory system, resembling to Cercaria macrogranulosa previously described from the same region of Brazil. Partial sequences of the ITS (ITS1-5.8S-ITS2) region and 28S gene of the nuclear ribosomal RNA operon, and partial sequences of mitochondrial nad1 and cox1 genes were obtained and compared with the data available for members of the family Echinostomatidae. Nuclear markers indicate that all samples of cercariae evaluated in the present study can be assigned to Rhopalias, but distinct from North American isolates of Rhopalias macracanthus, Rhopalias coronatus and Rhopalias oochi (divergence 0.2-1.2% in 28S and 0.8-4.7% in ITS). The lack of differences verified in both 28S and ITS in 5 out 6 studied samples suggested that they belong to the same species. However, nad1 sequences revealed that our cercariae correspond to three distinct species of Rhopalias (interspecific divergence: 7.7-9.9%), named here as Rhopalias sp. 1, found in B. straminea and G. ticaga, Rhopalias sp. 2 found in B. glabrata and D. lucidum, and Rhopalias sp. 3 also found in D. lucidum. They also differ by 10.8-17.2% from a North American isolate of R. macracanthus sequenced in this study. The cox1 sequences obtained for Rhopalias sp. 1 and Rhopalias sp. 2 (but not Rhopalias sp. 3) reveal that they are distinct from North American isolates of R. macracanthus (genetic divergence 16.3-16.5% and 15.6-15.7%, respectively), R. coronatus (9.2-9.3% and 9.3-9.5%) and Rhopalias oochi (9.0% and 9.5-10.1%). Encysted metacercariae with general morphology similar to that of the body of cercariae were found in tadpoles of Rhinella sp. from the same stream where snails harbored Rhopalias sp. 2, suggesting that the amphibians could act as second intermediate hosts of species of Rhopalias. Data obtained provide the first insights into the life cycle of this unusual echinostomatid genus.

Philophthalmus gralli in domestic waterfowl: An environmental study in an urban area from Brazil

Philophthalmosis is a zoonotic ocular disease that affects mainly domestic and wild avian species in different parts of the world. However, aspects related to its epizoology in domestic animals are not completely known. In the present study, 47 Muscovy duck (Cairina moschata), 8 mallards (Anas platyrhynchos platyrhynchos) and 6 African geese (Anser cygnoides), free-living in an urban lake in Belo Horizonte, Minas Gerais, Brazil, were evaluated for eye fluke infection. The animals were manually contained, and the conjunctival sac and nictitating membrane were evaluated by direct ophthalmic examination (DOE), in which the fluke burden was estimated by a semiquantitative scale. Moreover, the conjunctival sac lavage (CSL) technique was applied for the search of parasite eggs. When possible, the detected trematodes were carefully removed for fixed for taxonomic identification. In order to characterize the parasite-host-environmental system, malacological collections were performed at the locality, and the collected intermediate host mollusks (Melanoides tuberculata) were evaluated for infection with larval philophthalmids. In addition, wild vertebrates found dead in the locality, including one common gallinule (Gallinula galeata) and two capybaras (Hydrochoerus hydrochaeris), were necropsied for the search of eye flukes. Samples from the developmental stages obtained from the hosts were subjected to morphological and molecular studies (amplification and sequencing of a partial region of the Nad-1 gene). In the DOE, the presence of eye flukes was verified in 67% (4/6), 31% (15/47) and 25% (2/8) in geese, Muscovy ducks and mallards, respectively. In most cases, the birds showed mild parasitism (1-5 trematodes), with no apparent eye damage, characterizing a subclinical infection. In only one goose, which had a high fluke burden (20 trematodes), it was possible to obtain eggs by CSL. Regarding the malacological survey, 73/4545 (1.6%) specimens of M. tuberculata evaluated were found infected with megalurous cercariae, compatible with representatives of the family Philophthalmidae. Additionally, 147 flukes were recovered from a specimen of G. galeata found dead at the lake. The morphological and molecular study of parasites obtained from different hosts evaluated in this study enabled the identification of Philophthalmus gralli, a species native from Asia and introduced in the Americas. Factors such as the wide distribution of the intermediate host and the participation of domestic and wild reservoirs in the parasite transmission chain may favor the occurrence of parasite spillover from wild to domestic birds. Furthermore, the occurrence of the life cycle of P. gralli in an urban waterbody serves as an alert to the possibility of human cases of this zoonotic eye parasite.