[A case of intestinal myiasis in a bedridden elderly patient].

A 75-year-old man with type 2 diabetes and a history of previous empyema surgery was admitted to our hospital due to difficulty moving caused by chronic obstructive pulmonary disease and dehydration. During the first two days of hospitalization, intestinal myiasis was diagnosed after maggots were found in his diapers. After the maggots disappeared, he developed a fever, prompting antibiotic therapy for a suspected secondary infection, resulting in clinical improvement. Despite thorough home cleaning, no flies or maggots were found, and the source of infection and the fly species remained unknown. Recent reports suggest a higher prevalence of myiasis among the elderly, even with overall improvement in hygiene. While myiasis is typically mild, it is a condition that requires consideration in an aging society. Myiasis is a disease that should be considered in the differential diagnosis of the elderly, especially in people who are bedridden or frail.

Psychodid flies and their implicated role in human myiasis and pseudomyiasis.

Several psychodid flies are commonly associated with human-inhabited environments and have been increasingly implicated in cases of human myiasis. However, the basic biology of psychodid larvae is not well-suited for survival in the human intestinal or urogenital tract, making true, prolonged myiasis unlikely. In this review, we performed a systematic literature review of published cases of purported myiasis caused by psychodid flies, their identification, associated clinical findings, and treatment. We also discuss the anatomy and lifecycle of psychodid flies in relation to their purported ability to use human tissue as a nutritive source and survive in the human alimentary or urogenital tracts. Based on the range of non-specific and varied reported clinical manifestations, lack of observed collections, life cycle patterns of psychodid flies, the mechanics of their mouthparts, and breathing requirements, we conclude that most cases likely represent incidental findings, or in rare cases possibly pseudomyiasis, rather than true myiasis, and provide recommendations for clinical evaluation and reporting so that disease misclassification and unnecessary therapy do not occur.

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.

Myiasis on the tongue of a patient hospitalized in a psychiatric ward: A case report with a focus on diagnosis and clinical management.

INTRODUCTION: Myiasis is a disease caused by the infestation of fly larvae in the skin, which complete part of their life cycle by feeding on host tissues. OBJECTIVE: To report a rare case of tongue myiasis in a patient admitted to a psychiatric ward, focusing on clinical management. CASE REPORT: A dependent care and mentally challenged 55 years old male patient was hospitalized in a psychiatric ward. After 42 days, during the intraoral examination, it was noted numerous larvae peeking from inside of a wound on the dorsum of the tongue. The clinical diagnosis of myiasis was rendered. For the treatment, manual removal was performed initially and ivermectin (15 mg), metamizole sodium (500 mg/ml), and chlorhexidine digluconate (0.12%) were prescribed. After one week, larvae were no longer observed, and the wound was completely healed. CONCLUSION: Myiasis occurrence is uncommon in the mouth, however, its correct diagnosis and treatment are necessary to avoid further damage to patients, especially those who are hospitalized.

Efficacy of lotilaner against myiasis caused by Cochliomyia hominivorax (Diptera: Calliphoridae) in naturally infested dogs.

BACKGROUND: The New World screwworm fly, Cochliomyia hominivorax, is widely distributed across South America. This parasitic insect is a significant cause of primary myiasis in animals, including dogs. There is an urgent need for a rapid and efficient treatment to improve the recovery of affected animals. In the present study we evaluated the potential of lotilaner for the treatment of myiasis caused by C. hominivorax larvae in naturally infested dogs. Lotilaner belongs to the isoxazoline class of chemical compounds and is marketed as Credelio™ for use against ticks and fleas in dogs and cats. METHODS: Eleven dogs with naturally acquired myiasis were enrolled in this study based on the severity of lesions and the number of identified larvae. All animals received a single oral administration of lotilaner at a minimum dose of 20.5 mg/kg body weight. After treatment, the number of expelled larvae, live or dead, was determined at 2, 6 and 24 h, and the larval expulsion rate, larvicidal effect and overall efficacy were calculated. After 24 h, the remaining larvae were removed, counted and identified. The lesions were cleaned, and palliative treatment was administered when necessary, according to the animal's health status. RESULTS: All larvae were identified as C. hominivorax. The larval expulsion rate was 80.5% and 93.0% at 2 and 6 h post-treatment, respectively. Lotilaner showed an overall efficacy of 100% at 24 h post-treatment. CONCLUSIONS: Lotilaner demonstrated a rapid onset of action and a high efficacy against C. hominivorax. We therefore recommend lotilaner for the effective treatment of myiasis in dogs.

OPHTHALMOMYIASIS INTERNA WITH INVASION OF THE OPTIC NERVE.

PURPOSE: To report a case of ophthalmomyiasis interna with optic nerve invasion that was treated with oral ivermectin and prednisone. METHODS: Case report with retrospective review of medical records and multimodal imaging studies. RESULTS: A Christmas tree farmer in his sixties presented with expanding multicolored, spiraling photopsias in the left eye. The visual acuity measured 20/50, and examination and imaging findings showed subretinal tracks consistent with ophthalmomyiasis interna. After several weeks of spontaneous improvement, the visual acuity decreased to 20/150 and fundus examination showed new optic disc edema that was treated with ivermectin and prednisone. Despite the development of optic disc pallor, the visual acuity improved to 20/25. CONCLUSION: Subretinal fly larvae can occasionally exit the eye by invading the optic nerve. Treatment of optic nerve involvement with ivermectin and prednisone can result in an excellent visual outcome.

Number of rainy days in a week influencing screwworm navel myiasis in beef calves and efficacies of injectable and topical antiparasitics.

Rainfall incidence as a risk factor for umbilical myiasis by Cochliomyia hominivorax in newborn beef cattle and the preventive and curative efficacies of injectable and topical products against its larvae were evaluated. The prevalence of navel myiasis did not differ between sex, however, it did differ between seasons of the year, independent of animal sex, with it being higher in the rainy season than in the dry season for both sexes (males 64.6%, females 62.1%). During the rainy season, rains occurred intermittently and the number of rainy days in a week had a direct influence on prevalence, with an increase (≥87%) in the number of calves with navel myiasis caused by C. hominivorax. When it rained intermittently for four, five and six days in a week during the rainy season, calves had ≈12, 24 and 11 times greater chances, respectively, of having navel myiasis compared to a week without rain during the rainy season. The injectable products did not reach preventive efficacies higher than 35%, while all treatments of topic products reached 100% preventive efficacy at 10 days post-treatment. Only the formulations with 30% dichlorfenthion and 0.32% fipronil achieved 100% curative efficacy. The results reinforce the need for intensified inspection and healing of the umbilicus during the rainy season, mainly during rainier weeks. Furthermore, topical formulations may be a better alternative as a preventive treatment than avermectin formulations. However, the curative efficacy of the topical product containing dichlorvos did not demonstrate a relationship with preventive efficacy for newborn calves.

Diagnosis of Oestrus ovis infestation in sheep by PCR and enzyme-linked immunosorbent assay.

The aim of this study was to assess the suitability of PCR and ELISA as diagnostic method in young sheep naturally infested by Oestrus ovis larvae. The experiment was carried out from December 2020 to April 2021 with 39 lambs divided into two groups: infested (n = 26) and control treated group (n = 13). The infested group did not receive treatment against oestrosis, and the control group was treated with closantel (10 mg/kg orally) every 28 days in order to keep the animals as free as possible of O. ovis infestation. The clinical signs varied among animals regardless of the number of recovered larvae of each lamb, however, the thick mucus and mucopurulent nasal discharge scores were less frequent in lambs from treated group. There was no correlation between the nasal discharge score and the number of O. ovis recovered larvae (R² = 0.012, P = 0.165). Three control treated animals only presented first instar larvae (L1) (1 - 4 larvae/animal) which were smaller than L1 found in the lambs of the infested group. Ninety-two percent of the lambs from infested group (24/26) were parasitized by O. ovis with number ranging from 1 to 54 larvae per animal. A gradual increase in plasma IgG (anti-antigen of O. ovis larvae) levels of animals from infested group after the third week of the trial was observed, whereas the control lambs had low levels of IgG until the end of the experiment. The PCR had low sensitivity (26 %) and high specificity (100 %), and it presented poor agreement (k = 0.177) with the larvae detection after the lamb slaughter. The oestrosis clinical signs were not related to larvae infestation intensity and ELISA showed a greater advantage over the PCR technique in identifying animals that are carrying O. ovis.

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.

Severe Vaginal Myiasis: Successful Management With Ivermectin.

Myiasis refers to infestation of living animals or humans by maggots or fly larvae. Urogenital myiasis is a rare condition that is linked to poor sanitary conditions and limited access to healthcare and with few published case reports. Here, we describe the case of a 67-year-old homeless woman with multiple comorbidities, who presented with extensive vaginal myiasis requiring inpatient management with ivermectin, ceftriaxone, and metronidazole and daily larvae extraction and debridement. The relevance of this case is providing a report of a successful management with ivermectin of a case of severe vaginal myiasis. Severe cases of vaginal myiasis can require repeated debridement of necrotic tissue and systemic antibiotics in addition to antiparasitic medication. People living under poor sanitary conditions and with poor hygienic practices are at increased risk for severe vaginal myiasis.

The efficacy of fluazuron in the management of blowfly strike in sheep.

The blowflies Lucilia spp. and Chryomya spp. feature prominently as a leading cause of myiasis and production losses in sheep in South Africa. With chemical means of preventing and treating blowfly strike being a common manner of control, new molecules or formulations effective against blowfly strike are needed as resistance becomes more of a problem. For this study we evaluated the potential of topical application of fluazuron on sheep as an additional means to control blowflies. When pure fluazuron was applied to raw meat at the recommended dose for cattle, significant effects on adult fly development were observed. However when applied topically to post-mortally collected sheep pelts at the same dose rate, no significant effects were observed on larval repellence or larval development with fly development progressing as expected. A subsequent pharmacokinetic study showed virtually no systemic absorption together with significant wool binding. Despite demonstrating that fluazuron was effective against blowfly larvae, wool binding of the molecule preclude its use.

Oestrid myiasis at a cross-road.

The oestrids are a genuinely unique group of Diptera that represent many species whose larvae parasitize mammals, feeding on live tissues of a wide range of hosts, from mice to elephants, causing obligatory myiases. Those have had greatest impact on the activities of humans and their use of animals (e.g., as food, recreation, in the conduct of wars). To a large extent their impact has been controlled through the use of therapeutic application of synthetic chemical treatments. While in some limited cases eradication has been achieved, it is unlikely to become the norm as these parasites seem well adapted to survive at low population densities and small smoldering foci are likely to present a challenge in the future. Should organic production eschew the use of parasiticides, other than for rescue of seriously ill animals, the foci of infection by these parasites will remain. In this article, we explore current scientific information on this group of parasites that may have become an anachronism in modern livestock parasitology, identify gaps in our knowledge as well as the suggestions for the management of these parasites in the era of genomics and proteomics.

Effectiveness of sarolaner in the clinical management of furuncular myiasis in dogs naturally infested with Dermatobia hominis (Diptera: Cuterebridae).

BACKGROUND: The human botfly, Dermatobia hominis, is a common cause of furuncular myiasis in dogs in Latin America. Lesions can be single or multiple, each harboring an individual larva, presented as an erythematous nodule that causes pruritus and pain. Typical treatment consists of sedation for removal of larvae by surgical incision or manual pressure. Medications to kill the larva before its extraction can reduce inflammation and discomfort and provide a less traumatic larval removal. Isoxazolines are broad-spectrum ectoparasiticides with larvicidal activity previously reported in the treatment of screwworm myiasis in companion animals. The aim of this study was to evaluate the effectiveness of sarolaner as part of the clinical management of furuncular myiasis in dogs caused by D. hominis larvae. METHODS: Ten short-haired mixed breed dogs naturally infested with D. hominis were enrolled. Clinical diagnosis was achieved by observation of skin nodules and visualization of larval motility through the lesion orifice. Sarolaner was administered at manufacturer recommended dose for fleas and ticks. Lesions were reexamined 24 h post-treatment and assessed for viability of larvae. Larvae were removed by digital compression and identified as D. hominis. RESULTS: Seventy-five D. hominis larvae were retrieved from ten dogs. No live larvae were observed, demonstrating 100% larvicidal efficacy of sarolaner. Skin lesions were healed 30 days post-treatment and new lesions were not observed. CONCLUSIONS: Sarolaner seems to be effective as larvicidal treatment for dogs with furuncular myiasis, reducing discomfort caused by the presence of the larva in the skin and facilitating its safe removal.

Furuncular myiasis caused by Dermatobia hominis in five cats and efficacy of topical fluralaner for its treatment.

BACKGROUND: Dermatobia hominis (D. hominis) is a botfly that causes furuncular myiasis in several species of domestic and wild animals. However, reports of feline infestation by larvae of this dipteran are rare. OBJECTIVE: To report the natural occurrence of furuncular myiasis caused by D. hominis in five cats and the efficacy of topical fluralaner for its treatment. ANIMALS: Five adult mixed-breed cats (four males, one female) were diagnosed and treated, all living in the state of Rio de Janeiro, Brazil. RESULTS: The cats were treated with topical fluralaner. After this treatment, the larvae were dead after 24 h in three cats and after 48 h in two. There was spontaneous expulsion of larvae in two cats, and it was necessary to perform manual expression for removal of dead larvae in the other three cats. CONCLUSIONS AND CLINICAL IMPORTANCE: Dermatobia hominis can cause furuncular myiasis in cats, although this appears to be less common than in other animal species. Topical fluralaner proved to be effective in the treatment of this parasitic disease.

Effect of a novel juvenoid fenoxycarb on the pupal-adult transformation in the blowfly, Chrysomya megacephala (Fabricius, 1794) (Diptera: Calliphoridae).

Chrysomya megacephala (Fabricius, 1794) (Diptera, Calliphoridae) acts as a vector of many disease-causing pathogens. It causes myiasis in human beings and other living vertebrates. In the present study, the effect of a juvenile hormone analog (JHA), fenoxycarb, was evaluated on pupal-adult transformation by exposing pupae (0 and 1-day-old) of blowfly. Pupae were topically treated with different concentrations of the compound, viz., 20, 40, and 80 µg/µl applied on the posterior dorsum with the help of a micropipette. The effects comprised various developmental aberrations, such as delayed pupal-adult ecdysis duration, pupal mortality, formation of pupal-adult intermediates, eclosion failure, reduced adult emergence, and formation of abnormal adults. The freshly molted pupae (0 day) were more susceptible as compared to 1-day-old pupae. Pupal mortality was highest at 80 µg. Normal adult emergence was completely inhibited at day 0 pupae treated with 80 µg of the fenoxycarb. These results demonstrate that fenoxycarb was capable of successfully inhibiting the pupal-adult transformation, and thus, it can be used to control this myiasis-causing agent.

Effects of Gasterophilus pecorum infestation on the intestinal microbiota of the rewilded Przewalski's horses in China.

Horse botflies have been a threat to the Przewalski's horses in the Kalamaili Nature Reserve in Xinjiang of China since their reintroduction to the original range. As larvae of these parasites could infest the intestine of a horse for months, they could interact with and alter the structure and composition of its intestinal microbiota, affecting adversely its health. Nonetheless, there are no such studies on the rewilded Przewalski's horses yet. For the first time, this study characterizes the composition of the intestinal microbiota of 7 rewilded Przewalski's horses infected severely by Gasterophilus pecorum following and prior to their anthelmintic treatment. Bioinformatics analyses of the sequence data obtained by amplicon high throughput sequencing of bacterial 16S rRNA genes showed that G. pecorum infestation significantly increased the richness of the intestinal microbial community but not its diversity. Firmicutes and Bacteroidetes were found the dominant phyla as in other animals, and the parasitic infestation decreased the F/B ratio largely by over 50%. Large reduction in relative abundances of the two genera Streptococcus and Lactobacillus observed with G. pecorum infestation suggested possible changes in colic and digestion related conditions of the infected horses. Variations on the relative abundance of the genus groups known to be pathogenic or symbiotic showed that adverse impact of the G. pecorum infestation could be associated with reduction of the symbiotic genera Lactobacillus and Bifidobacterium that are probiotics and able to promote immunity against parasitic infection.

Efficacy of afoxolaner (NexGard®) on the treatment of myiasis caused by the New World screwworm fly Cochliomyia hominivorax (Diptera: Calliphoridae) in naturally infested dogs.

New World screwworm (NWS) myiasis is an infestation by Cochliomyia hominivorax larvae that consume the living tissue of warm-blooded animals, including humans. Domestic dogs are among the potential hosts of these flies that lay their eggs on the edges of wounds. NWS myiasis cases can be fatal if untreated. Treatment with parasiticides must be fast-acting, long-lasting and show 100% efficacy, since open wounds can be reinfested. Afoxolaner is a molecule from the isoxazoline family with proven ectoparasiticide action against fleas, ticks and mites in dogs. Fourteen healthy client-owned dogs, naturally infested by C. hominivorax larvae, were treated with afoxolaner (NexGard®) as per label recommendations, providing at least the minimum dosage of 2.5 mg/kg. Maggot infestations were classified as light (fewer than 10 larvae), mild (from 10 to 20 larvae) or severe (more than 20 larvae), according to the number of larvae found in the wound and/or collected from the ground after treatment. Twenty-four hours post-treatment, infested lesions were carefully inspected and collected larvae were counted and classified as live or dead. All maggots were identified as second and third instar larvae of C. hominivorax and were found dead within 24 h after treatment, demonstrating 100% larvicidal efficacy against C. hominivorax.

Psychoda albipennis myiasis as a rare cause of erectile dysfunction: A case report.

Urogenital myiasis occurring with the settlement of fly larvae of the order Diptera is facultative and is rarely encountered in humans. This study presents a case of urogenital myiasis caused by Psychoda albipennis in a 42-year-old male patient. The patient was admitted to our hospital with complaints of groin pain, pollakuria and erectile dysfunction and claimed that he saw motile larvae in his urine. Three larvae were collected from the patient's urine, microscopically examined and identified as fourth-stage larvae of P. albipennis. The patient's complaints ceased after the application of an antibiotic and urinary antiseptic. It was concluded that myiasis should be considered in patients with urogenital complaints.

Bloody Diarrhea Caused by Intestinal Myiasis in an Infant: A Case Report and Review of Pediatric Literature.

Intestinal myiasis caused by fly larvae parasitic in gastrointestinal tract was rare reported in children. We reported an infant with bloody diarrhea caused by intestinal myiasis. A 1 year and 7 months old boy presented with the only symptom of bloody diarrhea of unknown origin. In the second week of onset, numerous moving worms were observed in the bloody stool after bowel preparation with polyethylene glycol for colonoscopy. The bloody diarrhea disappeared after 1 week of combined therapy with albendazole and metronidazole. On follow-up after 6 months, the patient remained well without bloody diarrhea. In conclusion, intestinal myiasis being a rare disease that is very challenging to diagnose, physicians should remember it when they receive cases of bloody diarrhea with non-specific symptoms without any apparent cause.

High morbidity cutaneous enzootic myiasis by Dermatobia hominis (Diptera: Oestridae) in sambar deer (Rusa unicolor).

This study describes the first known occurrence and treatment of enzootic cutaneous myiasis by Dermatobia hominis in a herd of sambar deer (Rusa unicolor). Sambar deer are clinically affected by enzootic cutaneous myiasis during the spring and summer in Rio de Janeiro, Brazil. Through direct inspection and clinicopathological evaluation in the herd with 80 R. unicolor, it was observed that infestation by D. hominis caused 100% morbidity. At histological exam, skin had eosinophilic and granulomatous chronic active severe necrohemorrhagic dermatitis associated with botfly and moderate surrounding fibroplasia. The systemic treatment with oral ivermectin at 0.08% was effective in 93.7% of deer with enzootic cutaneous myiasis after fourteen days. After treatment, the skin deer had eosinophilic and granulomatous chronic severe dermatitis associated with degenerated botfly and severe fibroplasia. Notable differences in leukocyte profile were observed between groups pre- and post-treatment. Decrease of relative values of neutrophils and eosinophils were significant in the treated deer group. An increase of relative values of monocytes was also confirmed in the treated group. Sambar deer was the only species affected by D. hominis, even though several other wild herbivores were kept in the same area. More studies are needed to elucidate the susceptibility of R. unicolor to D. hominis cutaneous infestations.