Philophthalmus sp. (Trematoda) in a human eye

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.

PHILOPHTHALMUS HECHINGERI N. SP. (DIGENEA: PHILOPHTHALMIDAE), A HUMAN-INFECTING EYE FLUKE FROM THE ASIAN MUD SNAIL, BATILLARIA ATTRAMENTARIA

Two cases of human philophthalmosis have been reported in Japan. Gravid flukes removed from the eyes of the patients were broken, but their morphological characteristics suggest that an unknown species of the genus Philophthalmus is involved as a pathogen for humans. The mitochondrial DNA barcode of the human eye fluke enabled us to discover its larval stage from the Japanese mud snail, Batillaria attramentaria. The discovered cercaria had previously been temporarily described as "Philophthalmid sp. I." In this study, we examined the infection status of B. attramentaria with Philophthalmid sp. I found on a muddy seashore of the Seto Inland Sea, Japan, and the resulting metacercariae were experimentally administered to Japanese quails to develop them into the gravid adult stage. The complete specimens of the adult and larval stages allowed us to describe a new species. Based on morphological and molecular analyses, Philophthalmus hechingeri n. sp. is proposed for the human-infecting eye fluke in Japan. The natural definitive hosts of the new species are unknown. However, the habitat of B. attramentaria suggests that shorebirds (seagulls, sandpipers, and plovers) might be the possible candidates.

A systematic review of flukes (Trematoda) of domestic goose (Anser anser dom.)

Trematodes are one of the most numerous and widespread groups of parasitic invertebrates among helminths, characterized by a complex life cycle. As the final host, digenetic flukes parasitize vertebrates, including domestic waterfowl. Infection of hosts with parasitic digenetic worms causes huge economic damage to poultry. But trematode fauna of domestic geese are presented mainly only for individual regions. Despite the fact that there is already a systematic review of tapeworms and acanthocephala of domestic birds – geese and ducks, there are, unfortunately, no review articles on the taxonomy of digenetic flukes for geese (Anser anser dom.). Taking into account the relevance of the topic, based on our own and extensive literature data, we set the task to determine the general species composition of digenetic flukes (Trematoda), parasitizing in domestic geese which have been recorded in the world until 2020. Each Trematoda species is provided with the following data: scientific name, authority and year, first, second intermediate, auxiliary and final hosts, site in the host body, collecting localities and geographic distribution, and literature sources. Currently it is established that there are 149 species of helminths parasitising domestic geese. The taxonomic composition of the class Trematoda registered in domestic geese consists of 2 classes, 14 families, 30 genera and 65 species. Of all the species of trematodes parasitizing in domestic geese, 44 species have been recorded in Europe, 26 species in Asia, 6 species in North America, 1 species in South America, 1 species in Africa and 2 species in Oceania. Three species are registered in domestic geese (Echinoparyphium recurvatum, Echinostoma revolutum, Prosthogonimus ovatus) are cosmopolitan parasites. The biggest species diversity is characterized by the families Echinostomatidae (17 species) and Notocotylidae (12 species). There are 11 species of digenetic flukes recorded in domestic geese Cyclocoelum mutabile, Echinostoma grande, E. paraulum, E. revolutum, E. robustum, Hypoderaeum conoideum, Paryphostomum novum, P. pentalobum, Catatropis verrucosa, Notocotylus attenuatus, N. parviovatus) on the territory of Azerbaijan. Four of them (Echinostoma revolutum, Hypoderaeum conoideum, Paryphostomum novum, Notocotylus attenuatus) were also noted in the course of our helminthological studies. The trematode Cyclocoelum mutabile was recorded in domestic ducks only in Azerbaijan. Most species of trematodes were found in the north-eastern part (total 9 species) and southern part (total 5 species) of Azerbaijan. This is due to the widespread distribution of molluscs – intermediate hosts of digenetic flukes, in these regions. Eighteen species of digenetic flukes parasitize both birds and mammals (Rodentia, Carnivora, Lagomorpha, Artiodactyla). And eleven species of trematodes are of medical importance, registered in humans.

Spread of An Avian Eye Fluke, Philophthalmus gralli, Through Biological Invasion of An Intermediate Host

Philophthalmus is a genus of globally distributed parasitic eye flukes with some members of the genus found in disparate locales. In particular, Philophthalmus gralli, a zoonotic trematode, appears to be a relatively new introduction to the Americas, facilitated by spillover from the invasive snails Melanoides tuberculata (red-rimmed melania) and Tarebia granifera (quilted melania), which were introduced via the aquarium trade, and perhaps furthered by avian dispersal. Given that two known intermediate hosts of Philophthalmus flukes are actively expanding their range as a result of human activities, we hypothesize that this spread is also associated with the spread of Philophthalmus flukes. To address this, we systematically reviewed the literature and examined whether the global expansion of P. gralli flukes is associated with the spread of invasive snails M. tuberculata and T. granifera. Here, we show that (1) specimens of P. gralli are only found in intermediate snail hosts M. tuberculata or T. granifera, suggesting intermediate host specificity for these 2 species, and (2) specimens of P. gralli have rarely been found outside the ranges (native and introduced) of M. tuberculata or T. granifera. Given the importance of distribution information of parasites in the role of identifying parasite invasions, we also review the known distribution of all Philophthalmus species. Considering recent outbreaks in humans and wild and domestic animal species, the continued spread of Philophthalmus presents a potential threat to veterinary and public health and conservation.

Ocular Trematodiasis Caused by the Avian Eye Fluke Philophthalmus in Southern Texas

A trematode identified as a Philophthalmus sp was extracted from the bulbar conjunctiva of a patient in southern Texas with short-distance travel to Mexico. This parasite is very rarely reported from humans, and species identification is challenging. Aspects of diagnosis, zoonotic transmission, and unresolved questions about Philophthalmus spp are discussed.

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.

Trematode Fluke Procerovum varium as Cause of Ocular Inflammation in Children, South India

Larvae of this fluke are novel causes of granulomatous eye disease in children.

Trematodes are recognized as a group of emerging parasites in tropical countries. We identified a trematode as a cause of ocular granulomas that developed in children who bathed in ponds or rivers in South India. DNA was isolated from patients’ surgically excised granulomas and from the trematode cercariae (larvae) released by the snail Melanoidestuberculata in water in which the children bathed. Real-time and conventional PCRs were performed that targeted ribosomal DNA regions spanning the internal transcribed spacer 2 and 28S sequences of this trematode. The PCR-amplified products were subjected to bidirectional sequencing. Analysis of sequences for the granuloma samples and the trematode cercariae showed maximum sequence similarity with Procerovumvarium (family Heterophyidae). Our results confirmed the etiology of the ocular infection, implicating snail vectors as environmental risk factors for ocular parasitosis.

Pathology and first report of natural eye infection with the trematode Philophthalmus gralli (Digenea, Philophthalmidae) in Tinamus major (Tinamiformes, Tinamidae), Costa Rica

The eye-fluke Philophthalmus gralli (Philophthalmidae Looss, 1899) was found in six birds known as great tinamous (Tinamus major) reared in a wild animal shelter located in Alajuela, Costa Rica. The birds presented conjunctival hyperemia, blepharitis, anorexia and weakness. Some of them suffered from unilateral blindness and ocular loss. After morphometric analysis, the specimens showed characteristics compatible with the digenean trematode P. gralli. The clinical signs of infection were resolved by manual removal of the adults, treatment with praziquantel and relocation into an environment without a natural water source. In order to determine if an ongoing cycle of this pathogen was present in the shelter, the habitat of the birds was inspected for the presence of infected intermediate hosts and contaminated water and objects. It was found that the snails Melanoides tuberculata acted as the intermediate host, and reared the infectious stages toward other animals, as shown by the reproduction of ocular philophthalmiasis in chickens artificially infected with excysted metacercaria. Moreover, three out of every ten snails found in the place were infected with rediae of P. gralli, raising the possibility of the dispersion of the parasite into new environments as well as the imminent zoonotic risk. The finding of P. gralli in Costa Rica is the first official report in Central America.

Pathology and first report of natural infections of the eye trematode Philophthalmus lachrymosus Braun, 1902 (Digenea, Philophthalmidae) in a non-human mammalian host

The avian eye trematode Philophthalmus lachrymosus Braun, 1902 is for the first time referred naturally occurring in a non-human mammalian host. Previously, natural infections with P. lachrymosus and other species of Philophthalmus have been occasionally reported from man, with few data on experimental infections of non-human mammals. Results presented here are related to the report of two cases of philophthalmosis due to natural infections of wild Brazilian capybaras, Hydrochaeris hydrochaeris L., 1766 with P. lachrymosus and associated pathology. Clinical signs, gross and microscopic lesions as well as new morphometric data on the parasite are presented.

Cercariae of a species of Philophthalmus detected in a freshwater snail, Semisulcospira libertina, in Japan

Cercariae belonging to the genus Philophthalmus (Digenea: Philophthalmidae) were detected in a freshwater snail Semisulcospira libertina collected from Innai Town, Oita Prefecture, Kyusyu, Japan. This is the first record of the cercaria of this genus from East Asia and from Semisulcospira. Daughter rediae and cercariae are briefly described and morphologically compared with similar but unidentified ones reported from Japan. Cercariae were found encysting on the surface of the bottom of the container and metamorphosed into a flask-like metacercaria characteristic of Philophthalmus.

The first human case in Mexico of conjunctivitis caused by the avian parasite, Philophthalmus lacrimosus

Species of Philophthalmus parasitize primarily the eyes of wild and domestic birds. A variety of mammals, including humans, occasionally serve as the intermediate as well as the definitive hosts for this parasite, although human cases are extremely rare. Here, we report a case of human conjunctivitis caused by an infection with Philophthalmus sp. in Mexico. The patient was a 31-yr-old male who visited an ophthalmologist in Los Mochis, Sinaloa, Mexico, because of a foreign-body sensation in his left eye for 2 mo. A small live parasite was found in the connective tissue of the bulbar conjunctiva and was removed surgically under local anesthesia under ophthalmoscopic observation. The parasite was identified morphologically as Philophthalmus lacrimosus Braun, 1902. This is the first case of human philophthalmosis in Mexico and, to our knowledge, the first human case of P. lacrimosus infection in the world.

Presumed trematode-induced granulomatous anterior uveitis: a newly recognized cause of intraocular inflammation in children from south India

PURPOSE

To describe the epidemiologic, clinical, and histopathologic features of a presumed trematode granulomatous anterior uveitis, primarily in children from south India.

DESIGN

Prospective, noncomparative, case series.

METHODS

Children with clinical evidence of granulomatous anterior uveitis were selected for the study. Those who presented with distinct anterior chamber nodules were evaluated. Demographic details, such as clinical findings and course of illness, were noted. Patients underwent either medical treatment or surgical aspiration of the lesion based on the size of the lesion. Aspirated materials were subjected to histopathologic analysis and cultures for bacteria and fungi. Response to treatment and final visual status were evaluated.

RESULTS

One hundred thirteen patients with anterior chamber nodules were seen between 1998 and 2000. Ninety-three (82.4%) were males and 20 (17.7%) were females. The median age was 11.0 years. All patients were from south India and all gave a history of bathing or swimming in the local pond or river. All had normal systemic work ups. Of the 113 patients, 110 had anterior chamber nodules and three had both anterior chamber and subconjunctival nodules. Aspirates of the anterior chamber lesions revealed lymphocytes, intact and necrotic neutrophils, and eosinophils admixed with histiocytes. One subconjunctival nodule showed necrotizing granuloma, displaying the tegument of a trematode. Those patients who were followed had good visual recovery after medical or surgical intervention or both.

CONCLUSION

The present study shows a newly recognized granulomatous anterior uveitis caused by a presumed water-borne trematode infection. This infection appears to be a common cause of pediatric granulomatous anterior uveitis in south India.

An outbreak of trematode-induced granulomas of the conjunctiva

PURPOSE

To describe the epidemiologic, clinical, and histopathologic features of trematode granulomas of the conjunctiva, eyelid, and anterior chamber in pediatric patients.

DESIGN

Prospective noncomparative case series.

PARTICIPANTS

Forty-one children from a southern Indian village with conjunctival granulomas.

METHODS

The village of Sellananthal was selected for a field visit after analysis of earlier hospital-based allergic conjunctival granuloma cases. Children with ocular diseases were examined, and histories of exposure to assumed risk factors and clinical findings were evaluated. Selected patients were brought to the base hospital for excisional biopsy. Serial sections obtained from the excised nodules were examined for the presence of a parasite.

MAIN OUTCOME MEASURES

Histopathologic examination of excised conjunctival lesions or response of lesions to local medical therapy.

RESULTS

In this year-long prospective study, 41 children (16 years or younger; 38 boys and 3 girls) with clinical features of allergic conjunctival granulomas were examined. Thirty-four patients were from a single village located in the southern Indian state of Tamil Nadu; the remaining 7 were from various parts of the same state. All children swam in their village's freshwater pond. Twenty patients with nodules less than 5 mm in diameter received medical treatment; 13 with larger nodules underwent surgical excision of the lesions. Nine of these 13 cases revealed a zonal granulomatous inflammation admixed with eosinophilic leukocytes; 4 of these 9 displayed fragments of the tegument and internal structures of a trematode and Splendore-Hoeppli phenomenon. The remaining 4 of the 13 cases revealed nongranulomatous inflammation made up of lymphocytes, histiocytes, and eosinophils. Eight patients refused surgical treatment.

CONCLUSIONS

In southern India, one cause of allergic conjunctival granulomas in children seems to be trematode infection. The clustering of cases in a single village and exposure to a village freshwater pond indicate the need for an epidemiologic investigation and study of the parasite's life cycle. Sporadic cases from other parts of the state with similar histories of exposure to their local pond or river water suggest a widespread distribution of the etiologic agent.

A first instance of human philophthalmosis in Israel

Conjunctivitis due to the trematode Philophthalmus in a 13-year-old Israeli girl is described. A single worm, probably a mature Philophthalmus palpebrarum, was detected on the palpebral conjunctiva of the upper eyelid of the right eye. Removal of the worm resulted in rapid abatement of the ocular symptoms. This is the first documentation of human philophthalmosis in Israel.

Philophthalmus species, probably P. palpebrarum, in Israel: description of the eye fluke from experimental infection

Following a recent incident of human philophthalmosis in Israel, the intramolluscan larval trematode fauna in snails randomly collected from the suspected water source was checked. Of the snails examined, only Melanopsis praemorsa shed cercariae, including a Philophthalmus cercaria. To identify the philophthalmid species involved, chicks were experimentally infected with metacercariae of the trematode, subsequently yielding mature trematodes resembling those of P. palpebrarum. The majority of trematodes obtained, whether from one-worm infections or from multiple-worm infections resulting in a single trematode in one of the eyes, were relatively small and showed only immature eggs in their uteri. This finding suggests that the existing descriptions of two species of Philophthalmus purportedly harbouring eggs with non-oculate miracidia, namely P. palpebrarum and P. nyrocae, are actually based on immature specimens from one-worm infections that precluded cross-fertilisation. If this be true, then all species of the genus Philophthalmus produce eggs that, when mature, contain oculate miracidia. The species encountered in Israel is thus most likely P. palpebrarum.

Human conjunctivitis caused by the bird parasite Philophthalmus

We removed a trematode of the species Philophthalmus from under the left upper eyelid of a 66-year-old man who had follicular conjunctivitis for three weeks. After removal of the parasite, the conjunctivitis resolved.