Human ophthalmomyiasis caused by Oestrus ovis-first report from Croatia and review on cases from Mediterranean countries

Perception and management of Oestrus ovis human myiasis by physicians: Exploratory survey in an endemic area (Italy)

BACKGROUND

Myiasis caused by the sheep nasal botfly is endemic in countries where sheep and goats are largely reared, while humans serve as incidental hosts. Ophthalmomyiasis in humans caused by Oestrus ovis is documented globally but is most prevalent in Mediterranean countries, highlighting the significance of this myiasis as a neglected disease.

METHOD

A thorough questionnaire covering frequency of disease occurrence, seasonal patterns, and management of O. ovis was forwarded to clinicians in Italy gathering data from 100 respondents across diverse regional and occupational backgrounds.

RESULTS

Majority of respondents were from endemic areas of the Southern Italy and main islands, like Sardinia (52%) and Sicily (42%), with 81% representing physicians. Notably, 31% of physicians reported treating ophthalmomyiasis cases, while 80% expressed interest in further information. Seasonal trends revealed a peak during summer (χ² = 29.429, df = 4, p < 0.001), notably among outdoor workers in contact with farm animals (χ ² = 18.059, df = 2, p < 0.001). Diagnosis relied on symptoms or parasite detection, with ocular regions being the most common site of infestation. O. ovis was identified in 13% of cases (χ² = 20.368, df = 3, p < 0.05), with physicians emphasizing the importance of removing larvae painlessly to avoid complications. Finally, physicians reported the efficacy of mercuric oxide ointment and the use of topical povidone-iodine for ocular localization, combined with antibiotics and corticosteroids.

CONCLUSIONS

Diagnostic challenges and the persistence of recurrent infestations highlight the need for enhanced disease surveillance and clinician knowledge to effectively manage and mitigate the impact of ophthalmomyiasis as it continues to emerge as a significant public health concern.

Morphological and Molecular Identification of Obligatory Myiasis-Causing Species in Wild Cervids in Croatia

The infestation of ruminants by fly larvae of the Oestridae family can lead to nasopharyngeal or subcutaneous myiasis, which can harm animal welfare and productivity on sheep and cattle farms. The infestation of wild ruminants allows them to serve as reservoirs for subsequent transfer to domestic animals. The fly species most commonly responsible for myiasis have been well studied in many parts of the world, but less so in southeastern Europe. Here, we identified three botfly species among 197 subcutaneous larvae and 138 nasopharyngeal larvae from 36 wild roe deer (Capreolus capreolus) and 9 wild red deer (Cervus elaphus) at 30 locations across Croatia. Instars were stored in 75% ethanol and their species and developmental stage were identified based on morphological and morphometric keys. Subcutaneous larvae in both cervid species were identified as Hypoderma diana, while nasopharyngeal larvae were identified as Cephenemyia simulator in roe deer and Pharyngomyia picta in red deer. Partial sequencing of the gene-encoding mitochondrial cytochrome oxidase subunit I confirmed the taxonomic classification of C. stimulator and P. picta but was unable to confirm that of H. diana for lack of previously published sequences. This study appears to be the first to combine the morphological and molecular characterization of myiasis-causing botflies in wild cervids in southeastern Europe.

First Molecular Diagnosis of Oestrus ovis (Linnaeus, 1758) Larvae Causing Conjunctival Ophthalmomyiasis in Mexico City, Mexico

PURPOSE

Human ophthalmomyiasis is a rare ocular parasitosis that results from the accidental infestation of dipteran larvae of several species, including Oestrus ovis (Linnaeus, 1758). This study aims to present the fourth documented human case of ophthalmomyiasis in Mexico, identifying the etiological agent through morphological and molecular analyses. Additionally, we investigated the phylogenetic position and genetic distances among different specimens globally characterized based on mitochondrial Cox1 sequences.

METHODS

A total of five larval specimens were extracted from the patient's eye, with two specimens allocated for identification based on morphological features using a stereomicroscope, and the remaining three preserved in absolute ethanol, one of them used for subsequent analysis using molecular methods. The mitochondrial Cox1 region was amplified and sequenced using automated Sanger sequencing. The resulting sequence was deposited in GenBank under accession number OR440699 and subjected to BlastN analysis against 35 other Cox1 sequences of O. ovis from GenBank. The identity and phylogenetic position of the strains were further explored using parsimony and maximum likelihood phylogenetic methods.

RESULTS

Morphological examination of the larval specimens extracted from the patient's eye unequivocally identified them as O. ovis species. BlastN analysis and comprehensive phylogenetic investigations involving a total of 36 Cox1 sequences confirmed the taxonomic identity of the larvae. Notably, our sequence was positioned within the cluster formed by the Brazilian and two Iranian samples. This finding underscores a shared genetic ancestry among these distinct geographical isolates and provides valuable insights into the evolutionary relationships within O. ovis populations.

CONCLUSION

The presence of O. ovis infestation in Mexico City suggests potential shifts in environmental conditions favoring fly proliferation, highlighting the need for vigilance in urban healthcare settings.

Infectious eye disease in the 21st century-an overview

Infectious diseases affecting the eye often cause unilateral or asymmetric visual loss in children and people of working age. This group of conditions includes viral, bacterial, fungal and parasitic diseases, both common and rare presentations which, in aggregate, may account for a significant portion of the global visual burden. Diagnosis is frequently challenging even in specialist centres, and many disease presentations are highly regional. In an age of globalisation, an understanding of the various modes of transmission and the geographic distribution of infections can be instructive to clinicians. The impact of eye infections on global disability is currently not sufficiently captured in global prevalence studies on visual impairment and blindness, which focus on bilateral disease in the over-50s. Moreover, in many cases it is hard to differentiate between infectious and immune-mediated diseases. Since infectious eye diseases can be preventable and frequently affect younger people, we argue that in future prevalence studies they should be considered as a separate category, including estimates of disability-adjusted life years (DALY) as a measure of overall disease burden. Numbers of ocular infections are uniquely affected by outbreaks as well as endemic transmission, and their control frequently relies on collaborative partnerships that go well beyond the remit of ophthalmology, encompassing domains as various as vaccination, antibiotic development, individual healthcare, vector control, mass drug administration, food supplementation, environmental and food hygiene, epidemiological mapping, and many more. Moreover, the anticipated impacts of global warming, conflict, food poverty, urbanisation and environmental degradation are likely to magnify their importance. While remote telemedicine can be a useful aide in the diagnosis of these conditions in resource-poor areas, enhanced global reporting networks and artificial intelligence systems may ultimately be required for disease surveillance and monitoring.

Retrospective study of Oestrus ovis larvae infestation in small ruminants in Grenada, West Indies

Oestrosis is a nasal cavity myiasis caused by Oestrus ovis larvae from Oetrus ovis diptera flies in small ruminants. The presence of the larvae in the nasal cavity is known to cause rhinitis and sinusitis which can negatively impact the productivity of small ruminants. The aim of the present study was to estimate the prevalence of Oestrus ovis larvae infestation in sheep and goats presented for necropsy. We reviewed necropsy records of sheep and goats submitted to the Veterinary Pathology diagnostic laboratory at St. George's University from 2001 to 2017. Out of 104 goat necropsy cases, Oestrus ovis larvae were observed in 8 goats giving a prevalence of 7.7% (95% confidence interval (CI):3.38% to 14.6%). Similarly, from the 47 sheep necropsies, Oestus ovis larvae were observed in 4 sheep (8.5%) (95% CI: 2.83% to 20.46%). There was no significant difference in Oestrus ovis larvae infestation rates between sheep and goats (p = 1.000, Fisher's exact test). Oestrosis was an incidental finding in all the small ruminants examined at necropsy. This is the first report on Oestrus ovis larvae infestation in small ruminants in Grenada.

Ophthalmomyiasis Externa and Importance of Risk Factors, Clinical Manifestations, and Diagnosis: Review of the Medical Literature

OBJECTIVE

This review aims to describe and compare the risk factors, clinical course, diagnosis, and parasitologic features of external ophthalmomyiasis. We also discuss the different preventive measures and the effect of global warming in a large case series reported from January 2000 to December 2022.

METHODS

We perform a literature review of reported cases of external ophthalmomyiasis to determine the clinical characteristics, therapeutic management, and information on the organisms that most commonly cause external ophthalmomyiasis.

RESULTS

A total of 312 cases of external ophthalmomyiasis were recorded. The most common causative organism was Oestrus ovis (Linnaeus) (Diptera: Oestridae), accounting for 72.1% of cases, followed by Dermatobia hominis (Linnaeus Jr. in Pallas, 1781) (Diptera: Oestridae) at 5.4%, Lucilia sericata (Meigen) (Diptera: Calliphoridae) at 0.96%, and Chrysomyia bezziana (Villeneuve) (Diptera: Calliphoridae) at 0.96%. Before experiencing symptoms, 43.6% of cases reported having direct contact with flies or being hit in the eye, 33% reported no associated risk factors, 9.3% reported living with sheep and goats, and 7.7% reported a history of foreign objects entering the eye. The most common symptoms for those affected by O. ovis were sudden onset, including a foreign body sensation and movement, redness, tearing, itching, swelling, irritation, photophobia, burning, and ocular secretion. In cases caused by D. hominis, symptoms included eyelid edema, pain, redness, itching, movement within the lesion, ocular irritation, and discharge. Regarding occupational or recreational activity, agriculture, and livestock had the highest incidence, followed by trades and technical activities, being a student, and having traveled to an endemic region for work or recreation.

CONCLUSION

Patients with red eyes may suffer from external ophthalmomyiasis, which requires a thorough examination to diagnose and treat it early. Moreover, as the temperature increases due to climate change, it is essential to consider how this will affect the spread of different pathogens.

Toxic External Exposure Leading to Ocular Surface Injury

The surface of the eye is directly exposed to the external environment, protected only by a thin tear film, and may therefore be damaged by contact with ambient particulate matter, liquids, aerosols, or vapors. In the workplace or home, the eye is subject to accidental or incidental exposure to cleaning products and pesticides. Organic matter may enter the eye and cause infection. Ocular surface damage can trigger a range of symptoms such as itch, discharge, hyperemia, photophobia, blurred vision, and foreign body sensation. Toxin exposure can be assessed clinically in multiple ways, including via measurement of tear production, slit-lamp examination, corneal staining, and conjunctival staining. At the cellular level, environmental toxins can cause oxidative damage, apoptosis of corneal and conjunctival cells, cell senescence, and impaired motility. Outcomes range from transient and reversible with complete healing to severe and sight-compromising structural changes. Classically, evaluation of tolerance and safety was carried out using live animal testing; however, new in vitro and computer-based, in silico modes are superseding the gold standard Draize test. This review examines how environmental features such as pollutants, temperature, and seasonality affect the ocular surface. Chemical burns to the eye are considered, and approaches to protect the ocular surface are detailed.

Ophthalmomyiasis externa caused by Oestrus ovis

This report describes the case of a woman in her early 20s who presented with a 3-day history of mobile foreign bodies and watering from her right eye. She had recently returned from vacation on a Greek island and presented to an ophthalmology unit in London, UK. A sample taken demonstrated Oestrus ovis infestation and confirmed the diagnosis of ophthalmomyiasis externa. She was treated with prophylactic topical antibiotics and subsequently made a full recovery. This was only the sixth presentation of O. ovis ophthalmomyiasis externa documented within the UK and the only case documented within the last 20 years. This is the fifth documented case found to have been transmitted within Greece.

Morphological and Molecular Identification of Oestrus ovis (Diptera: Oestridae) Larvae Collected from a Chinese Patient with Conjunctival Myiasis

PURPOSE

Human conjunctival myiasis, which is often misdiagnosed or missed clinically, is commonly caused by Oestrus ovis larvae. Here, pathogenic identification was performed for two maggots collected from a patient from China, to provide a clinical scientific basis for diagnosis and treatment.

METHODS

Morphological identification was performed using a microscope. Oestrus mtDNA cox1 and rDNA 28S were selected as target genes for duplex PCR amplification, followed by cloning, sequencing, and identification.

RESULTS

Morphological examination showed that the maggots were approximately 1.0-1.5 mm long, long-oval-shaped, segmented, and covered with small spines, with a pair of hooks in the scolex and claw-like spines at the telson. Therefore, they were identified as the first-instar larvae of O. ovis. Duplex PCR detected products of approximately 400 and 200 bp, consistent with the size of designed cox1 and 28S D7a gene fragments, respectively. Sequences of cox1 and 28S D7a from the samples in question had 99.5-100.0% and 96.2-100.0% similarity (respectively) to GenBank sequences of O. ovis specimens known to parasitize sheep, goats, and humans. However, some 28S D7a sequences exhibited 89.7-90.6% similarity to GenBank sequences of Oestrus sp. known to parasitize Capra pyrenaica (Artiodactyla: Bovidae) (Iberian ibex). Therefore, we considered that the larvae infecting the patient originated from sheep or goats, not Iberian ibex. The phylogenetic trees supported this conclusion.

CONCLUSION

This study implemented the first duplex PCR molecular identification of O. ovis larvae parasitizing human eyes in China as a complementary approach to morphological identification. Our results indicate that molecular tools can be utilized to aid in the diagnosis of opthalmomyiasis.

External Ophthalmomiasis Cases in Şırnak

Dermatological cases caused by myiasis make up approximately 20% of travel diseases. Ocular involvement occurred in approximately 5% of these myiasis cases. The conjunctival involvement of Oestrus ovis (O. ovis) larvae, which is the active agent in most ocular infestation cases in humans, causes external ophthalmomyiasis. External ophthalmomyiasis was diagnosed because of O. ovis first-stage larvae that were removed from the conjunctiva of three patients who applied to the Şırnak State Hospital Eye Clinic with complaints of foreign body sensation, burning, stinging, watering, and redness in the eyes and swelling of the eyelids in July and October. All symptoms of the patients disappeared within a few days after the removal of the larvae. Ophthalmomyiasis due to O. ovis must be kept in mind in the differential diagnosis of patients presenting with similar eye complaints in areas where sheep and goat husbandry is performed intensely.

External ophthalmomyiasis by Oestrus ovis in tourists visiting Italy. Report of three cases and a literature review

BACKGROUND

Oestrus ovis is a dipteran parasite responsible of myiasis in small ruminants and reported as the causative agent of myiasis in humans particularly in sheep farming areas. In recent years, several human cases had been reported without any previous history of exposure to livestock or visit to rural areas.

CASE PRESENTATION

We describe three clustered cases of ophthalmomyiasis externa in tourists in Sardinia and Sicily and discuss them in the light of the published literature. The patients presented ocular irritation, foreign body sensation, pain, redness, and lacrimation of the eyelids. After extraction, all the larvae were morphologically and molecularly confirmed as L1 instar of O. ovis larvae.

CONCLUSIONS

The present study points out the need to draw attention and awareness among the physicians, and to consider ophthalmomyiasis when consulted for conjunctivitis in the summer and spring seasons.

The First Genetically Confirmed Case of Human Ophthalmomyasis Due to Oestrus ovis (Diptera Oestridae) in Bosnia and Herzegovina

PURPOSE

Here we present a case of human ophthalmomyasis due to Oestrus ovis in a patient living in an urban area. Dipterians of the Ostridae family may occasionally deposit larvae into the human eye and cause ocular parasitosis called ophthalmomyasis. Cases like this are mostly connected with people who live in close contact with animals, like shepherds, but are rarely presented in urban population.

METHODS

The patient was presented at University Clinic due to problems with his left eye, that persist no matter on treatment in local clinic a few days before. During the slit lamp examination larvae was detected and extracted from the conjunctiva. Genomic DNA was isolated from the sample and genetic analysis was performed.

RESULTS

Larvae was identified as a first-stage larvae of O. ovis.

CONCLUSION

This is the first report of genetically confirmed case of ophthalmomyasis in Bosnia and Herzegovina. In cases like this, clinicians should be aware of possibility of this rarely described presentation of ocular parasitosis since even the urban population can be accidentally affected due to a lack of natural hosts.

EXTERNAL OPHTHALMOMYIASIS CAUSED BY OESTRUS OVIS (A CASE REPORT)

The work deals with atypical conjunctival infection of Czech patient with Oestrus ovis larvae. Ophthalmomyiasis is infestation of mammalian eyes by the larvae or worms of some flies. The most common cause of human myiasis is the Sheep. Shepherds are infected in habitats, but human eye disease outside the areas of abundant hamsters is rare. We describe a case of eye disease in a middle-aged man from the Czech Republic who spent a summer holiday seven weeks before examination in the north of Greece. During the first examination he was completely treated and no further problems were reported. Ophthalmomyiasis externa should be considered as a possible infection of travelers to the southern endemic regions when returning with an acute causeless onset of a one-sided foreign body sensation in the eye.