Feline ophthalmomyiasis externa caused by Cuterebra larvae: four cases (2005-2020)

CASE SERIES SUMMARY

Described are four cats diagnosed with ophthalmomyiasis externa caused by Cuterebra larvae. Medical records were retrospectively reviewed to identify cats with ophthalmomyiasis externa between 2005 and 2020 at Cornell University Hospital for Animals. Signalment, history, clinical and diagnostic findings, treatment and outcome were recorded. All cats were young (< 3 years of age), had outdoor access and were initially examined during the summer months. All cases had unilateral disease with the right eye affected. Two cases had nictitating membrane lesions and two had orbital disease. Concurrent superficial corneal ulceration was present in three cats. Two cats suffered from pyrexia, suspected secondary to inflammation from the larval infestation. Successful larval removal was performed in all cats, which resulted in improvement of discomfort and clinical signs. A corneal ulcer persisted in one cat, which was lost to follow-up prior to ulcer resolution. Parasite identification confirmed Cuterebra species infestation in all cases.

RELEVANCE AND NOVEL INFORMATION

To the authors' knowledge, this is the first report of feline ophthalmomyiasis externa caused by Cuterebra species. Parasite removal was successful in restoring comfort and resolving clinical signs in all cats with adequate follow-up information.

Ophthalmomyiasis in a preterm neonate resulting in blindness: A case report from Botswana

Myiasis is an infestation of human tissue by insect larvae. While rare, healthcare-associated myiasis has been reported from immobilized patients in resource-limited healthcare facilities in warm climates without adequate vector control measures. We describe a case of Ophthalmomyiasis in a hospitalized neonate in Botswana that resulted in vision loss. The neonate, who was initially hospitalized due to the complications of prematurity, received phototherapy for jaundice, and to avoid phototherapy-related retinopathy, the neonate's eyes were covered using cotton gauze and adhesive tapes that potentially damaged the skin as commercially available eye covering was not in stock. Therefore, eye covering was not changed and when the eye covering was removed almost 3 days after placement, insect larvae were noted in the patient's eyes and nose. Ophthalmologic evaluation revealed perforated corneal ulcer and uveal prolapse in the right eye resulting in complete blindness and corneal scarring of the left eye. The patient's clinical course was further complicated by an Enterobacter species bloodstream infection. This case highlights the importance of vector control as a major patient safety measure for neonatal units in warm climates. Flies had been observed in the room and mitigation measures included reducing fly populations through traps, screens, and removal of standing water and leftover food. Every mother and staff were sanitizing hands when entering the room and gowns were used. This case also reinforces the importance to conduct vigilant monitoring of patients, especially neonates with eyes covered during phototherapy.

Phthiriasis palpebrarum, thelaziasis, and ophthalmomyiasis

INTRODUCTION

Parasitic infections of the eye are a major cause of ocular-surface diseases globally. While most infections are treatable, parasites can cause varying levels of damage mostly due to late diagnosis or misdiagnosis as a result of doctors' unfamiliarity with their characteristics of latency and crypsis, as well as lack of awareness by the patients.

CASE REPORTS

In this study, we present three cases of phthiriasis palpebrarum, thelaziasis, and ophthalmomyiasis, respectively. Two of the cases were treated at the clinic and did not recur. One patient refused treatment and was lost to follow-up.

DISCUSSION

By evaluating the natural histories, morphology, symptoms, clinical findings, and treatment of these parasitic diseases, we systematically analyzed several distinct and unique parasite characteristics, especially latency and crypsis. Furthermore, we have proposed specific examination techniques and methods as well as prevention and treatment strategies from these specific perspectives, aiming to prompt timely diagnoses and early interventions for these diseases by health care workers and improve the public's awareness of parasitic infections.

CONCLUSION

Parasitosis on the ocular surface is a global infectious disease, and prevention strategies include maintaining personal and environmental hygiene and limiting contact with animals. We recommend that health care workers should enhance their ability to detect and diagnose these diseases while promoting the public's awareness of them in the context of our new perspectives.

Ophthalmomyiasis Caused by Chrysomya bezziana after Periocular Carcinoma

We treated a homeless man in Iran with a history of squamous cell carcinoma who had ophthalmomyiasis caused by Chrysomyabezziana parasites. This case highlights a much-neglected condition and describes measures to prevent it.

External ophthalmomyiasis by Oestrus ovis: A case report from Davangere

External ophthalmomyiasis is an infestation of the eye with larvae of Dermatobia hominis or Oestrus ovis (sheep bot fly). We describe a case of ophthalmomyiasis in a 38-year-old male, who presented with ocular foreign body sensation, redness, pain, and watering of the eye. The causative larvae were removed and sent to the laboratory for identification. By studying morphological features, it was identified as the first instar larvae of O. ovis. The patient was put on topical and oral antibiotics but was lost to follow-up. This is probably the first report from this part of Karnataka.

Orbital myiasis: A case report and literature review

RATIONALE

Myiasis is a parasitic disease caused by fly larvae of the Diptera order that infest human and other vertebrate animal tissues. Orbital myiasis is a potentially destructive infestation of the orbital tissues, which may affect individuals with previous ocular diseases or disorders of consciousness.

PATIENT CONCERNS

A 72-year-old man presented with a complaint of repeated pain for two years after trauma to his right eyelid and aggravated symptoms with larvae wriggling out for 2 days. An orbital computed tomography scan revealed right eyeball protrusion and periocular soft tissue edema. Two days later, magnetic resonance imaging showed that the shape of the right eyeball was changed and that the normal structure of the eyeball could not be identified.

DIAGNOSES

Due to the patient's symptoms and imaging examination results, the diagnosis of orbital myiasis was made.

INTERVENTIONS

The patient was treated by exenteration of the right orbit, and all necrotic tissues and larvae were removed. The defect was repaired via reconstruction with a pedicled musculocutaneous flap from the forehead region. Antibiotics and tetanus toxoid therapy were utilized to prevent potential bacterial infection.

OUTCOMES

The patient recovered well postoperatively and was discharged uneventfully. During the 6-month follow-up period, the wound healed well.

LESSONS

Advanced age and untreated eye trauma are risk factors for orbital myiasis. Timely removal of larvae and elimination of infections are important measures for protecting the eyeball.

Human myiasis caused by the reindeer warble fly, Hypoderma tarandi, case series from Norway, 2011 to 2016

Hypoderma tarandi causes myiasis in reindeer and caribou (Rangifer tarandus spp.) in most northern hemisphere regions where these animals live. We report a series of 39 human myiasis cases caused by H. tarandi in Norway from 2011 to 2016. Thirty-two were residents of Finnmark, the northernmost county of Norway, one a visitor to Finnmark, and six lived in other counties of Norway where reindeer live. Clinical manifestations involved migratory dermal swellings of the face and head, enlargement of regional lymph nodes, and periorbital oedema, with or without eosinophilia. Most cases of human myiasis are seen in tropical and subtropical countries, and in tourists returning from such areas. Our findings demonstrate that myiasis caused by H. tarandi is more common than previously thought. Healthcare professionals in regions where there is a likelihood of human infestation with H. tarandi (regions populated by reindeer), or treating returning travellers, should be aware of the condition. All clinicians are advised to obtain a detailed travel history when assessing patients with migratory dermal swellings. On clinical suspicion, ivermectin should be given to prevent larval invasion of the eye (ophthalmomyiasis). Since H. tarandi oviposits on hair, we suggest wearing a hat as a prevention measure.

Update on pathology of ocular parasitic disease

Parasites are a group of eukaryotic organisms that may be free-living or form a symbiotic or parasitic relationship with the hosts. Consisting of over 800,000 recognized species, parasites may be unicellular (Protozoa) or multicellular (helminths and arthropods). The association of parasites with human population started long before the emergence of civilization. Parasitic zoonotic diseases are prevalent worldwide including India. Appropriate epidemiological data are lacking on existing zoonotic parasitic diseases, and newer diseases are emerging in our scenario. Systemic diseases such as cysticercosis, paragonimiasis, hydatidosis, and toxoplasmosis are fairly common. Acquired Toxoplasma infections are rising in immune-deficient individuals. Amongst the ocular parasitic diseases, various protozoas such as Cystoidea, trematodes, tissue flagellates, sporozoas etc. affect humans in general and eyes in particular, in different parts of the world. These zoonoses seem to be a real health related problem globally. Recent intensification of research throughout the world has led to specialization in biological fields, creating a conducive situation for researchers interested in this subject. The basics of parasitology lie in morphology, pathology, and with recent updates in molecular parasitology, the scope has extended further. The current review is to address the recent update in ophthalmic parasites with special reference to pathology and give a glimpse of further research in this field.

Ocular parasitoses: A comprehensive review

Parasitic infections of the eyes are a major cause of ocular diseases across the globe. The causative agents range from simple organisms such as unicellular protozoans to complex metazoan helminths. The disease spectrum varies depending on the geographic location, prevailing hygiene, living and eating habits of the inhabitants, and the type of animals that surround them. They cause enormous ocular morbidity and mortality not because they are untreatable, but largely due to late or misdiagnosis, often from unfamiliarity with the diseases produced. We provide an up-to-date comprehensive overview of the ophthalmic parasitoses. Each section describes the causative agent, mode of transmission, geographic distribution, ocular pathologies, and their management for common parasites with brief mention of the ones that are rare.

Ocular myiasis caused by Chrysomya bezziana - a case report

Ophthalmomyiasis can have variable presentation depending on the type of fly, structures involved, and level of penetration. A 42-year-old female presented with extensive myiasis of the right eye. A lesion of 3×2 cm was noted at the medial canthus and was infested with maggots. The larvae were removed meticulously and the wound debrided. The larva isolated was that of Chrysomya bezziana (Old World screwworm). Computed tomography (CT) scan was normal. The wound was dressed regularly and healed by secondary intention. Ocular myiasis is a rare disease that can lead to life threatening consequences, such as intracranial extension. Prompt management with debridement and radical antibiotic therapy is essential.

larva

A 1-year-old female spayed mixed-breed dog was presented for evaluation of acute onset of lethargy and blepharospasm OD. Slit-lamp biomicroscopy revealed a segmented larva embedded in the inferonasal iris. Moderate anterior uveitis was present. After pharmacologic dilation, mild vitreal hemorrhage and chorioretinal migration tracks were identified. The dog was treated empirically for uveitis for 5 days, after which a keratotomy and larval foreign body extraction was performed. The dog recovered uneventfully from intraocular surgery and remained visual and comfortable. Parasite evaluation confirmed the larva to be a Cuterebra sp. To the authors' knowledge, this is the first report of canine ophthalmomyiasis interna anterior, and the first report of successful surgical removal from the anterior segment in a dog with preservation of vision.

A Case of Secondary Ophthalmomyiasis Caused by Chrysomya bezziana (Diptera: Calliphoridae)

Myiasis is the invasion of vertebrates' tissue by the larvae of a fly of the order Diptera. The objective of this paper is to present a rare case of secondary myiasis of ocular infestation by Chrysomya bezziana. A 55-year-old female from Sar village of Mazandaran Province, northern Iran), referred to Khatam Al-Anbia Hospital of Mashhad with extensive destruction of left orbital cavity. Existence of larvae was the major complaint in recent months. Some live larvae were removed from her destructed left eye. Primary diagnosis was myiasis of left upper lid (LUL) and suspected recurrent Basal cell carcinoma (BCC). The laboratory diagnosis was done in parasitology lab of Imam Reza Hospital of Mashhad and collected larvae were identified and confirmed to be larvae of the C. bezziana (Diptera: Calliphoridae). It is a case report of secondary ophtalmiomyiasis due to C. bezziana of a patient lives in Mazandaran Province.

Unilateral acute conjunctivitis due to Oestrus ovis in a veterinary doctor

Myiasis is the infestation of tissues and organs of animals or man by fly larvae. We report a human case of external ophthalmomyiasis caused by the larvae of a sheep nasal botfly, Oestrus ovis, for the first time in a veterinary doctor. A 25-year-old veterinary doctor presented with severe symptoms of conjunctivitis. The larvae, 3 in number, were observed in the bulbar conjunctiva and the symptoms of the eye improved within a few hours of their removal. It is important for ophthalmologists to be aware of larval conjunctivitis as a significant possibility in the veterinary fraternity especially during the summer season.

Vidi, vini, vinci: External ophthalmomyiasis infection that occurred, and was diagnosed and treated in a single day: A rare case report

Ophthalmomyiasis is an infestation of eye with larvae or maggots of certain flies. Oestrus ovis (sheep nasal botfly) belonging to family Oestridae is the most common cause of human myiasis. We describe here an acute presentation of a case of external ophthalmomyiasis, i.e., infestation of conjunctiva due to first instar larvae of Oestrus ovis. In this case report the occurrence, diagnosis and treatment all took place in the setting of a single day. Prompt treatment by removal of larvae mechanically followed by instillation of antibiotic and steroid eye drops helped to prevent serious complications. The taxonomic identification of fly is also important as some fly species are capable of penetrating deeper tissues of eyes, which is sight threatening.

(Diptera: Calliphoridae) larva in an enucleated patient

Ophthalmomyiasis rarely occurs worldwide, and has not been reported in Korea. We present here a case of ophthalmomyiasis caused by Phormia sp. fly larva in an enucleated eye of a patient. In June 2010, a 50-year-old man was admitted to Dankook University Hospital for surgical excision of a malignant melanoma located in the right auricular area. He had a clinical history of enucleation of his right eye due to squamous cell carcinoma 5 years ago. During hospitalization, foreign body sensation developed in his right eye, and close examination revealed a fly larva inside the eye, which was evacuated. The larva was proved to be Phormia sp. based on the morphology of the posterior spiracle. Subsequently, no larva was found, and the postoperative course was uneventful without any complaints of further myiasis. This is the first case of ophthalmomyiasis among the literature in Korea, and also the first myiasis case caused by Phormia sp. in Korea.

External ophthalmomyiasis caused by Oestrus ovis: a rare case report from India

Myiasis of different organs has been reported off and on from various regions in the world. We report a human case of external ophthalmomyiasis caused by the larvae of a sheep nasal botfly, Oestrus ovis, for the first time from Meerut city in Western Uttar Pradesh, India. A 25-year-old farmer presented with severe symptoms of conjunctivitis. The larvae, 3 in number, were observed in the bulbar conjunctiva, and following removal the symptoms of eye inflammation improved within a few hours.