Prevalence of Oestrus ovis in small ruminants from the eastern Iberian Peninsula. A long-term study.

Oestrus ovis is an obligate parasite that causes myiasis in domestic ruminants, being commonly found in the Mediterranean area. From 2009 to 2019 a total of 3476 heads of culling sheep and goats from the Mediterranean coast of Spain were examined for the presence of O. ovis. The total prevalence was 56.3%, significantly higher in sheep than in goats (61.2% and 43%, respectively). Differences were found in the mean annual prevalence, with the highest value being registered in 2018 (61.7%) and the lowest in 2012 (50.3%). Autumn, for sheep, and winter, for goats, were the seasons with the highest number of infested specimens. Temperature, but not rainfall, was found to be associated with prevalence (p < 0.05). Most L1 were found in the anatomic region I (septum, meatus, and ventral conchae), while L2 and L3 were mainly located in regions II (nasopharynx, ethmoid labyrinth, and dorsal conchae), and III (sinuses). The overall intensity was 12.8 larvae per head, significantly higher in sheep (13.3) than in goats (3.5). Our results confirm the high prevalence of O. ovis in sheep and goats in this geographic area over the last decade, with the trend increasing in recent years in association with higher mean temperatures.

Major differences in the larval anatomy of the digestive and excretory systems of three Oestridae species revealed by micro-CT.

Oestrid flies (Diptera: Oestridae) do not feed during the adult stage, so they depend on an efficient assimilation and storage of nutrients during their parasitic larval stage. We describe the general morphology and provide volumetric data for the digestive and excretory organs of the three larval instars of the nasal bot fly Oestrus ovis L., using micro-computed tomography. The size of the digestive and excretory organs greatly increased across larval instars. In all instars, the two salivary glands were remarkably large and formed a 'glandular band' by coming together, but without lumina uniting, at their posterior ends. The distal region of the anterior Malpighian tubules was greatly enlarged and full of highly radio-opaque concretions. Moreover, the anatomy of O. ovis third-instar larva was compared to that of two species of, respectively, similar and different feeding habits: Cephenemyia stimulator (Clark) and Hypoderma actaeon Brauer. Whereas the general morphology and arrangement of the digestive and excretory systems of C. stimulator was similar to that of O. ovis, some differences were observed in H. actaeon: a swollen anterior region of the midgut, salivary glands shorter and not forming a 'band' and anterior Malpighian tubules narrowly uniform throughout their entire length.

Development and characterization of 15 novel polymorphic microsatellite loci for two important bot flies (Diptera, Oestridae) by next-generation sequencing.

Cephenemyia stimulator and Oestrus ovis are two important parasitic bot flies (Oestridae) species causing myiasis, with a potential negative impact on the welfare of the host. Using next-generation sequencing approach and bioinformatics tools, a large panel of possible microsatellites loci was obtained in both species. Primer pairs were designed for 15 selected microsatellite loci in C. stimulator and other 15 loci in O. ovis for PCR amplification. Loci amplification and analysis were performed in four populations of each species. The results demonstrated that all selected loci were polymorphic, with the number of alleles ranging from 2 to 6 per locus in C. stimulator and 3 to 13 per locus in O. ovis. This is the first time to describe these microsatellite loci for C. stimulator and O. ovis. These two sets of microsatellite markers could be further used for biogeographic and population genetics studies.

Rhinomyiasis by Oestrus ovis in a tourist returning from Corsica.

In the Mediterranean basin, one of the most important agents of myiasis is Oestrus ovis Linnaeus 1758 (Diptera, Oestridae). Herein, we report a rare case of nasal myiasis with a secondary infection complication in a patient from northern Italy who had been visiting Corsica. A healthy, 39-year-old Italian woman spent 2 weeks of vacation in Corsica in June 2018. During her stay, she suddenly felt a foreign body inside her nose, followed by cough, pain, burning at the pharyngeal level, cephalalgia, and nasal congestion with secretions from the nostrils. The clinical examination showed a hyperemic and irritated mucosa and endoscopic examination of the patient's nose and right maxillary sinus revealed three tiny mobile larvae, morphologically and molecular identified as L1 instar larvae of Oestrus ovis. The patient's infestation was probably imported from Corsica, as Mediterranean islands are ideal geographical areas for the development of O. ovis, and the timing of infestation match with the period of O. ovis larviposition. Although rhinomyiasis is rare, it should be considered in people returning from abroad presenting with an acute-onset and foreign body sensation in the nose.

Micro-computed tomography visualization of the vestigial alimentary canal in adult oestrid flies.

Oestrid flies (Diptera: Oestridae) do not feed during the adult stage as they acquire all necessary nutrients during the parasitic larval stage. The adult mouthparts and digestive tract are therefore frequently vestigial; however, morphological data on the alimentary canal in adult oestrid flies are scarce and a proper visualization of this organ system within the adult body is lacking. The present work visualizes the morphology of the alimentary canal in adults of two oestrid species, Oestrus ovis L. and Hypoderma lineatum (de Villiers), with the use of non-invasive micro-computed tomography (micro-CT) and compares it with the highly developed alimentary canal of the blow fly Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae). Both O. ovis and H. lineatum adults showed significant reductions of the cardia and the diameter of the digestive tract, an absence of the helicoidal portion of the midgut typical of other cyclorrhaphous flies, and a lack of crop and salivary glands. Given the current interest in the alimentary canal in adult dipterans in biomedical and developmental biology studies, further understanding of the morphology and development of this organ system in adult oestrids may provide valuable new insights in several areas of research.

Oestrus ovis external ophtalmomyiasis: a case report in Burgundy France.

BACKGROUND: External ophtalmomyiasis (EOM) is a zoonosis related to the presence of Oestrus ovis larvae at the ocular level in small ruminants (i.e. ovine, caprine). In humans, EOM is a rare cosmopolitan disorder, mostly described in warm and dry rural areas in patients living close to livestock areas. In metropolitan France (excluding Corsica), EOM is an exceptional disease with less than 25 cases recorded since 1917. CASE PRESENTATION: We report a case of EOM in a 19-years old man in the last week of September 2016 in Burgundy. CONCLUSION: The diagnosis of an EOM in Burgundy, a French region described as cold and humid, is surprising and could be due to a more marked climatic warming during the vegetative season in Burgundy resulting in the implantation of Diptera of the genus Oestrus sp. in this region.

First report of oestrosis in aoudad from southeastern Spain.

In spring 2016, we analyzed the skull of 44 aoudads (Ammotragus lervia) from Sierra Espuña Regional Park (SE Spain) for the presence of oestrid larvae. Oestrus ovis larvae were found in 27.3% of sampled hosts, with a mean intensity of 1.5 ± 6.1 larvae/per parasitized host (range 1-21). To our knowledge, this is the first report of oestrosis affecting this host species.

External ophthalmomyiasis: a case series and review of ophthalmomyiasis in Turkey.

Ophthalmomyiasis externa is the infestation of the superficial external ocular structures by fly larvae. This is a particularly rare condition, which has nevertheless been reported in several countries worldwide. It is common in sheep-farming areas, especially in Mediterranean countries. The patients may present with classic conjunctivitis, pseudomembranous conjunctivitis, conjunctival hemorrhages, punctuate keratitis, keratouveitis, and eyelid edema with erythema. Herein, we present three cases of external ophthalmomyiasis caused by Oestrus ovis larvae and review ophthalmomyiasis cases reported from Turkey.

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.

Bilateral Ophthalmomyiasis Externa of Lid by Musca domestica: A Rare Presentation.

A case of severe blepharoconjunctivitis in the last three weeks diagnosed the slit lamp as external ophthalmomyiasis. On ocular examination, numerous pupae were present on the lid margins, firmly adhering to the lid lashes bilaterally. All of them were removed mechanically under topical anesthesia. They were 67 in number. Healing occurred without any complications. In such cases of blepharoconjunctivitis, physicians should consider the possibility of ophthalmomyiasis externa, especially in places where high numbers of livestock are found. Otherwise, there is a chance of missing the diagnosis, which can be met with a more serious condition called ophthalmomyiasis interna.

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.

First report on molecular characterization of Oestrus ovis in sheep from India.

The objective of the present study is to characterize the dipteran larvae species infesting the sheep being maintained at SRRC, Mannavanur, by means of COI gene based PCR. During the last week of May 2021, post mortem examination of the skull of an Avikalin male sheep (20 months old) revealed the presence of larvae in its nasal sinuses. The larvae were washed in PBS (pH 7.2) and preserved in 70% alcohol. Total genomic DNA was isolated from the larvae using an initial step of grinding with liquid Nitrogen in a sterile mortar and pestle. Using the isolated genomic DNA from the larvae as a template, Cytochrome c oxidase subunit I (COI) gene based PCR was employed using the primers designed based on the COI gene of reference isolate of Oestrus ovis available in the GenBank. Full length COI gene (1534 bp) gene of Oestrus ovis in sheep from South India was targeted in the PCR experiment. The pTZ57R/T vector was used for the cloning of the PCR amplified fragment and the confirmed recombinant plasmid was subjected to sequencing experiments. In addition to morphological examination, based on COI gene based PCR, eventual sequencing experiments and BLAST analysis, it was confirmed that the larvae in the nasal sinuses of sheep from South India were Oestrus ovis. The South Indian isolate of Oestrus ovis is sharing 100% sequence identity both at nucleotide and amino acid levels with that of O. ovis from Spain. The North Indian isolate of O. ovis (from Jammu) exhibited 92% and 99% identity at respective nucleotide and amino acid levels with South Indian isolate. With other members of the subfamily Oestrinae, the share of per cent nucleotide and amino acid identities of South Indian O. ovis ranged from 85-86% to 95-96%, respectively. O. ovis from South India was grouped with the other members of Oestrinae from different geographical areas of the globe in the analysis of phylogenetic tree based on COI amino acid sequences. Based on the research findings, it is concluded that Oestrus ovis is the dipteran species infesting the sheep at Mannavanur, Tamil Nadu, India. To our knowledge, this is the first report on full length nucleotide sequences of COI gene of O. ovis in sheep from Indian subcontinent. Supplementary Information: The online version contains supplementary material available at 10.1007/s12639-024-01666-2.

Ophthalmomyiasis Externa: A Case Report in a Tertiary Care Center in Riyadh, Saudi Arabia.

Introduction: Ophthalmomyiasis externa, which is caused by Oestrus ovis larvae, is a parasitic eye infestation that is prevalent in tropical and subtropical regions. It occurs in rural settings and is associated with risk factors, such as poor sanitation and underlying health conditions. Reports on this disease in Saudi Arabia are rare. Case Presentation: A 30-year-old man from a rural area in Riyadh presented with severe left eye irritation and redness after being hit by an insect. Examination revealed seven motile larvae, which were identified as O. ovis, on the conjunctiva. The larvae were mechanically removed, and the patient was treated with topical antibiotics. On follow-up, four additional larvae were found and removed. Symptoms resolved completely, with no further larvae detected on subsequent follow-up. Conclusion: Thorough history and examination are essential for the diagnosis of ophthalmomyiasis, especially in rural areas. Early detection and intervention are vital to prevent serious complications. This case highlighted the importance of awareness among healthcare providers.

Nasopharyngeal Botflies Oestrus ovis and Cephenemyia stimulator in Roe Deer (Capreolus capreolus) from Northern Spain.

Two of 19 roe deer (Capreolus capreolus) in northern Spain were infested with Cephenemyia stimulator and one individual with Oestrus ovis. Three larvae of O. ovis were recovered from the nasopharynx of an adult female deer examined in February 2017, during the hunting season in the province of Burgos. The larvae were identified by morphology, and DNA sequencing from cytochrome oxidase subunit I and 28S rDNA confirmed the identification of both species of larvae. The possibility of O. ovis parasitizing roe deer should be considered in the diagnosis of nasal bots in cervids.

Efficacy of eprinomectin 5 mg/mL topical solution administered pour on at 1 mg per kg body weight against Oestrus ovis myiasis in sheep and goats.

The larvae of the nasal bot, Oestrus ovis, mainly parasitize sheep and goats and some species of wild Caprinae but other mammals and humans are also vulnerable to infestation. Eprinomectin 5 mg/mL topical solution (EPRINEX® Multi, Boehringer Ingelheim) administered at 1 mg eprinomectin per kg body weight pour on was recently authorized as an anthelmintic for sheep and goats with zero hours milk withdrawal in several countries in Europe. As the product in cattle has claims against a broad range of parasites including insect parasites and activity against O. ovis has previously been reported following extra-label use in sheep, its therapeutic efficacy against ovine and caprine O. ovis myiasis was evaluated in three regulatory compliant, masked clinical studies. Pre-study recovery of O. ovis larvae from five or six of six randomly selected animals per study site (Bulgaria, one site, sheep; Greece, two sites, sheep or goats) supported the inclusion of the animals from those sites into the studies. The study animals (34 animals per study) were ranked based on bodyweight and allocated randomly to remain untreated (control) or to be treated with eprinomectin 5 mg/mL topical solution at 1 mL per 5 kg body weight pour on. Treatment efficacy was determined based on O. ovis larval counts of eprinomectin 5 mg/mL topical solution-treated vs. untreated animals three weeks after treatment administration. Live O. ovis larvae, including all three instars in each study, were recovered from 13 or 16 of the 17 control animals in the sheep studies (range, 1 to 14 or 5 to 18 larvae, respectively) and from all 17 controls in the goat study (range, 7 to 18 larvae). In each study, eprinomectin 5 mg/mL topical solution-treated animals had significantly (p < 0.001) fewer live O. ovis larvae than the controls. Efficacy of the treatment was 100% and 91.3% against the combined parasitic O. ovis larval stages in sheep and in goats, respectively. The treatment was well accepted by all animals and no health problems were observed throughout the studies. The results of these studies demonstrated eprinomectin 5 mg/mL topical solution administered pour on at 1 mL per 5 kg body weight to be an efficacious and safe treatment of ovine and caprine oestrosis.

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.

Ophthalmomyiasis Externa due to Oestrus ovis Larvae: A Case Report.

A 23-year-old female presented with redness, itchiness, tearing, and foreign body sensation in her right eye after spending her holiday in Egypt. Slit lamp examination revealed about 15 mobile, whitish maggots that were microbiologically classified as Oestrus ovis larvae. All parasites could be removed without subsequent complications.

External Ophthalmomiasis Cases in Sirnak

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 Sirnak 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.