EVALUATION OF THE OPHTHALMIC DISEASE AND HISTOPATHOLOGIC EFFECTS DUE TO THE OCULAR TREMATODE PHILOPHTHALMUS ZALOPHI ON JUVENILE GALAPAGOS SEA LIONS ( ZALOPHUS WOLLEBAEKI)

A Molecular Phylogenetic Study of the Eye Fluke Philophthalmus lacrymosus (Trematoda: Philophthalmidae) Found in Larus dominicanus (Aves: Laridae) from Brazil

PURPOSE

Species of the genus Philophthalmus are eye flukes with a complex taxonomy, which began to be improved with the help of molecular data only recently. However, most described species have never been placed into a phylogenetic context. In this study, eye flukes previously found on kelp gulls, Larus dominicanus, from Brazil and identified as Philophthalmus lacrymosus were subjected to molecular analysis.

METHODS

For the molecular analyses, we analyzed parasites found in six infected gulls (one worm per bird) collected from different municipalities of the state of Santa Catarina, Brazil. We carried out the amplification and sequencing of the partial region of the 28S and cox1 genes and the data obtained were compared with sequences available to philophthalmid species and subjected to phylogenetic analysis.

RESULTS

The isolates of P. lacrymosus from Brazil grouped in well-supported clades with five other species of Philophthalmus with sequences available for comparison. Interspecific divergences of 0.1-1.6% in 28S and 8.2-14.9% in cox1 were found in relation to other isolates of Philophthalmus spp. Two cox1 haplotypes differing in one nucleotide (0.1%) were found between the six eye flukes isolates in gulls from different localities. The Brazilian isolates grouped in a subclade with parasites identified as P. lacrymosus in Portugal; however, the molecular divergences found in cox1 (8.2-8.5%) strongly suggest that these isolates belong to different species. The phylogenetic trees obtained and the intergeneric divergences to species of the genera Cloacitrema and Parorchis did not support the validity of the genus Natterophthalmus, for which P. lacrymosus was proposed as the type species in the past.

CONCLUSION

As P. lacrymosus was described from Brazil, we recommend that this name be applied to the South American isolates and that the Portuguese isolates be provisionally considered as Philophthalmus sp., a probable cryptic species. Moreover, data obtained supports the previous morphology-based synonymizing between Natterophthalmus and Philophthalmus. Considering our results and most of previous reports of P. lacrymosus in South America, we suggest this species presents a marine life cycle.

Ocular disease caused by the trematode Philophthalmus lachrymosus in free-living kelp gulls (Larus dominicanus) of Brazil

In this study, clinical, parasitological and histopathological findings of thirteen kelp gulls (Larus dominicanus) found infected with eyeflukes in Brazil are presented. Parasites detected in the ventral conjunctival fornix were identified as Philophthalmus lachrymosus [mean intensity of infection: 16 (5-36) worms/bird]. Eleven birds (85%) presented signs of systemic disease, such as emaciation, dehydration and depressed consciousness. Conjunctival hyperemia was observed in 22 eyes (85%). Keratitis, corneal ulcers, corneal abscess and chemosis were also detected in some eyes (4-8%). Histopathologic lesions, likely due to the parasite attachment to the conjunctiva, were found in the eyes of one infected bird that died from unrelated causes. Philophthalmosis by P. lachrymosus is here reported as a clinically relevant eye disease in kelp gulls.

Evaluating the Possibility of Transfusion Medicine, Through Crossmatching in Juvenile Galapagos Sea Lions (Zalophus wollebaeki)

The Galapagos sea lion (Zalophus wollebaeki) is an endemic pinniped to the Galapagos archipelago, and like most wild mammals, is at risk for anemia due to trauma, infectious disease, and poor nutrition. This study evaluated the health status of 26 juvenile Galapagos sea lions on the island of San Cristobal prior to evaluating 100 crossmatch combinations. On evaluation, all but one sea lion had no major systemic abnormalities. Of the 100 crossmatches performed, 23% had minor reactions. The most significant reaction was weak macroscopic agglutination found in 4% of samples. The small percentage of agglutination reactions suggests a small proportion of naturally occurring alloantibodies in this species and may be consistent with a low risk of acute immune-mediated hemolytic transfusion reaction.

MEASUREMENT OF INTRAOCULAR PRESSURE USING REBOUND TONOMETRY IN ANESTHETIZED PERUVIAN FUR SEALS (ARCTOCEPHALUS AUSTRALIS) FROM PUNTA SAN JUAN, PERU

Ocular disease in pinnipeds under human care is well described, and intraocular pressure (IOP) can be impacted by a variety of ophthalmic conditions. Species-specific reference parameters from clinically normal animals are instrumental for understanding how ophthalmic diseases may impact ocular pressures. IOP measurements were obtained using rebound tonometry from free-ranging Peruvian fur seals (Arctocephalus australis unnamed subspecies) at Punta San Juan, Peru, over a 6-yr period (2010-2016). Retrospective data obtained from 108 (81 adults and 27 neonates comprising 69 females and 39 males) anesthetized fur seals with normal anterior segment ophthalmic examinations was included in the analysis. Differences in IOP from each eye were compared to categorical variables (age, year, sex, restraint) using an independent-samples t test. All univariate results with a significance of P < 0.05 were included in multivariate analysis. Of the 13 general linear models evaluated, the top two for both the right and the left eye included age class when all variables were evaluated simultaneously. Neonates had significantly lower IOP values than adults in both the right eye (17.5 mm Hg; 95% confidence interval [CI]: 14.0-21.1 mm Hg compared to 33.5 mm Hg; 95% CI: 31.0-36.1 mm Hg, respectively) and the left eye (18.4 mm Hg; 95% CI: 14.4-22.5 mm Hg compared to 32.3 mm Hg; 95% CI: 29.3-35.3 mm Hg, respectively). Anesthesia method was not statistically significant (P > 0.05). This is the first report of normal IOP measurements for any fur seal species. Described data can be used to improve diagnosis and management of ocular alterations in pinnipeds.

Morphology and molecules resolve the identity and life cycle of an eye trematode, Philophthalmus attenuatus n. sp. (Trematoda: Philophthalmidae) infecting gulls in New Zealand

Trematodes of the genus Philophthalmus are cosmopolitan parasites that infect the eyes of birds and mammals. They have the potential to affect the survival of their hosts and a few cases of human philophthalmiasis have occurred worldwide. Adults of known Philophthalmus species have never been recorded from bird hosts in New Zealand, despite their cercarial stage being a focus of various studies. Here, we describe a new species of Philophthalmus infecting New Zealand red-billed and black-backed gulls, Philophthalmus attenuatus n. sp. It is distinguished from other marine species of Philophthalmus by its long, thin body shape, consistently longer vitelline field on the left, and its body reflexed at the ventral sucker. We use molecular methods to complete the life cycle of this species, matching it with the larval stage infecting the mud whelk, Zeacumantus subcarinatus, and present a preliminary cox1 phylogeny. In addition, we comment on the validity of some taxonomic characters used to differentiate species of this genus, discuss potential colonisation routes to New Zealand and comment on the potential for zoonotic infection.