Botfly myiasis: case report and brief review

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.

Graphical abstract

The Botfly, A Tropical Menace: A Distinctive Myiasis Caused by Dermatobia hominis

Dermatobia hominis, also known as the human botfly, is native to tropical and subtropical Central and South America and seen in travelers from endemic to temperate regions including the United States and Europe. Cutaneous infestation botfly myiasis involves the development of D. hominis larvae in the skin and is common in tropical locations. The distinct appearance of a cutaneous D. hominis infestation facilitates early diagnosis and intervention where cases are common. However, the identification of D. hominis in temperate regions may prove challenging due to its rarity. D. hominis may be misdiagnosed as folliculitis, an epidermal cyst, or an embedded foreign object with secondary impetigo. One should have a heightened suspicion in someone returning from a vacation in an endemic area, such as Belize. Here we describe the presentation, differential diagnosis, and treatment and encourage enhanced preventative measures among tourists when visiting tropical and subtropical regions. Additionally, we propose a novel classification system for assessing the various stages of infestation and suggest that patients reporting travel to Latin America and experiencing pain disproportionate to an insect bite should lead physicians to consider myiasis caused by D. hominis.

Cutaneous Myiasis

Myiasis is defined as the infestation of live vertebrates, either humans or animals, with dipterous larvae. Many organs can be infested by these larvae with cutaneous myiasis being the most common form. Cutaneous myiasis can be divided into three categories: localized furuncular myiasis, migratory myiaisis and wound myiasis, which occurs when fly larvae infest the open wounds of the host. Human myiasis has worldwide distribution, with more species and a heavier burden in tropical and subtropical countries. In recent years with increased travel to the tropics, myiasis has become common in returning travelers from these regions, Furuncular myiasis, mainly Dermatobia homonis becomes the most common form seen among them. Treatment is based on full extraction of the larva and no antibiotic treatment is needed. Understanding the mode of transmission of each type of myiasis may help to prevent the infestation.

Myiasis caused by Dermatobia hominis: countries with increased risk for travelers going to neotropic areas

Here, we review the human botfly (Dermatobia hominis), which belongs to a group of Diptera generically known as "myiasis-causing flies," characterized by the ability of their larvae to develop in animal flesh. In addition to its medical and economic importance, there is an academic interest in this botfly because of its peculiar biology, particularly because a phoretic diptera is needed to complete the life cycle. The larvae penetrate the host's skin, causing furuncle-like lesions that are pruritic, painful, and resemble subcutaneous nodules, producing irreversible perforations in the skin. Although D. hominis is distributed from Mexico to Argentina, a review performed by our working group from 1999 to 2015 determined that the countries with the highest infection rates in travelers are Belize, Bolivia, and Brazil. Interestingly, infected men show a higher variation in the distribution of the lesions than in women. Many treatment schemes have been suggested, including the application of highly dense liquids to the lesion to cause anoxia in the D. hominis larvae. We showed, for the first time, a Bayesian inference between D. hominis and other myiasis-causing flies. The flies grouped into two main clusters according to their capacity to produce facultative and obligatory myiasis, and D. hominis was phylogenetically close to Cuterebra spp.

First report of furuncular myiasis caused by the larva of botfly, Dermatobia hominis, in a Taiwanese traveler

A case of furuncular myiasis was reported for the first time in a 29-year-old young Taiwanese traveler returning from an ecotourism in Peru. Furuncle-like lesions were observed on the top of his head and he complained of crawling sensations within his scalp. The invasive larva of botfly, Dermatobia hominis, was extruded from the furuncular lesion of the patient. Awareness of cutaneous myiasis for clinicians should be considered for a patient who has a furuncular lesion and has recently returned from a botfly-endemic area.

Rickettsiae, protozoa, and opisthokonta/metazoa

Rhizobiales (formerly named Rickettsiales) cause in rare instances meningitis and meningovasculitis, respectively. In case of history of exposure, infection by Rhizobiales needs to be considered since both diagnosis and therapy may be extremely difficult and pathogen-specific. The same applies to protozoa; in this chapter, Babesia species, free-living amoebae and Entamoeba histolytica infection, including severe meningitis and brain abscess, infection by Trypanosoma species (South American and African trypanosomiasis) are discussed with respect to history, epidemiology, clinical signs, and symptoms as well as differential diagnosis and therapy. Parasitic flatworms and roundworms, potentially able to invade the central nervous system, trematodes (flukes), cestodes (in particular, Cysticercus cellulosae), but also nematodes (in particular, Strongyloides spp. in the immunocompromised) are of worldwide importance. In contrast, filarial worms, Toxocara spp., Trichinella spp., Gnathostoma and Angiostrongylus spp. are seen only in certain geographically confined areas. Even more regionally confined are infestations of the central nervous system by metazoa, in particular, tongue worms (=arthropods) or larvae of flies (=maggots). The aim of this chapter is (1) to alert the neurologist to these infections, and (2) to enable the attending emergency neurologist to take a knowledgeable history, with an emphasis on epidemiology, clinical signs, and symptoms as well as therapeutic management possibilities.

Cutaneous furuncular myiasis: Human infestation by the botfly

Dermatobia hominis, the botfly, is indigenous to Central and South America. Its usual host is a mammal, often a horse or cow. Cutaneous furuncular myiasis, human infestation by the botfly, has rarely been reported. Symptoms of infestation include a locally painful, firm furuncular lesion, often with a centrally located pore. Due to their infrequent occurrence, these lesions are often misdiagnosed as cellulitis, leishmaniasis, furunculosis, staphylococcal boil, insect bite or sebaceous cyst - conditions with similar presentations. The present case reiterates the need to think of 'zebras' when hearing 'hoof beats' that may have originated in a different land.

Myiasis after study trip to French Guiana

Cutaneous myiasis is usually a harmless tropical disease caused by infestation with larvae from a variety of flies. Because of its rare occurrence in Europe, it is often misdiagnosed. Increased travel to tropical regions has correspondingly increased the number of cases observed in Europe. The furuncular type of cutaneous myiasis in a 31-year-old biology student was diagnosed upon his return from French Guiana. The student cultured one of the larvae to obtain a botfly. This case is discussed in the light of the current literature on pathogenesis, incidence and therapy of cutaneous myiasis.

Infestação por miíase em prolapso retal: relato de caso e revisão de literatura

INTRODUÇÃO: a miíase é uma afecção causada pela presença de larvas de moscas em órgãos ou tecidos do homem e de outros animais. Sua localização preferida em humanos é na pele, com ocorrências descritas nas cavidades naturais. Seu tratamento é baseado na remoção mecânica das larvas e no desbridamento cirúrgico de tecidos desvitalizados. OBJETIVO: descrição do caso de um paciente com prolapso retal associado à infestação por miíase, discutindo sua incidência, sintomatologia e tratamento. RELATO DO CASO: L.C.S, 36 anos, masculino, com prolapso retal há um ano. Habitante de região rural, com baixo nível sócio-econômico, não possuía banheiros ou qualquer tipo de saneamento básico em sua residência. Ao exame proctológico, evidenciava-se prolapso retal edemaciado, com áreas cavitárias com necrose, secreção purulenta e grande quantidade de larvas de míiase. Realizou-se retirada mecânica das larvas com posterior debridamento cirúrgico. Optou-se pela confecção de uma colostomia em alça do sigmóide, devido à extensa área cruenta com lesão esfincteriana interna. CONCLUSÕES: O acometimento da miíase retal em prolapsos é raro, e deve ser prontamente diagnosticado e tratado. Um simples exame proctológico é fundamental para este fim. Salienta-se a necessidade contínua da educação em saúde, bem como se enfatiza a importância dos hábitos de higiene na população.

Cutaneous myiasis

Myiasis is the infestation of living tissue by the larvae of flies in the order Diptera. Cutaneous involvement is the most common type of myiasis. Cutaneous myiasis can be subdivided into furuncular, migratory, and wound myiasis. Each subtype is reviewed with discussion of the larvae involved, presenting signs and symptoms, clinical differential diagnoses, and treatment. Preventive measures are also described.

LEARNING OBJECTIVES

At the conclusion of this learning activity, participants should be familiar with the causal agents, clinical manifestations, and treatment of human cutaneous myiasis.

Cerebral myiasis associated with angiosarcoma of the scalp: case report

OBJECTIVE

Primary human cerebral myiasis is an exceedingly rare condition and is almost never encountered by physicians in developed countries. The case report summarizes a case of extensive cerebral myiasis in a periurban community in the United States.

CLINICAL PRESENTATION

After a minor motor vehicle accident, police brought a 75-year-old man to the emergency room because he was observed to have a large cranial lesion. Examination revealed a 15 x 17 cm frontal bone defect with eroded frontal dura, exposed cortex, and massive cortical maggot infestation.

INTERVENTION

The patient was empirically treated with intravenous antibiotics for meningitis. Maggots (Phaenicia sericata, or the green bottle fly) were removed by suction, attrition, and gentle contact exposure to a mild bleach solution. Biopsy of the scalp and cranium revealed angiosarcoma, for which operative treatment was refused. The patient was transferred to a skilled nursing facility for palliative care where he died 3 months later.

CONCLUSION

This is the first published case of cerebral myiasis in the United States. Although human cerebral myiasis is rare, conditions do exist in this country that permit myiasis.

Human botfly infestation presenting as peri-auricular mass

To report a new cause of peri-auricular mass in children: cutaneous myiasis-botfly infestation. Case report. The human botfly (Dermatobia hominis) is found in the tropics of Central and South America. However, cases of infestation are uncommon in the United States. We present the case of a 5-year-old girl with cutaneous myiasis in order to expand the differential diagnosis for a peri-auricular mass in children. In our report, the parasite was initially identified as sparganum, but was later reclassified by the center for disease control and prevention (CDC) as a botfly larva. Parasitic infection should be considered with a newly noted head and neck mass, and cutaneous myiasis should be included in the differential diagnosis. Cutaneous myiasis has not been previously reported in the literature describing the peri-auricular region as the site of occurrence. Furthermore, when an unusual parasite is extracted from a lesion, it should be confirmed by an authority such as CDC for definitive diagnosis, so appropriate plan of care and follow up can be instituted.

Human botfly larva in a child's scalp

The botfly is the name for several families of hairy flies the larvae of which live as parasites in the bodies of mammals. Reported are the presentation, diagnosis, and noninvasive therapy for a botfly larva in the scalp of a 14 year old.

Furuncular myiasis caused by Dermatobia hominis, the human botfly

Myiasis is a common travel-associated dermatosis. Travelers to many parts of Central and South America are susceptible to infestation by Dermatobia hominis. Despite the common name of human botfly, D hominis infests a broad range of mammals and is a severe pest to economically important farm animals in endemic regions. The adult female does not lay the eggs on the host. Instead, the adult female infests hosts indirectly by using blood-feeding arthropods to serve as phoretic vectors to transport the eggs. We present a patient who acquired Dermatobia when bitten by a day-active mosquito during a visit to Guatemala. He had a locally painful, firm furuncular lesion with a central pore that drained serosanguineous exudates. The patient applied an occlusive ointment and recovered the larva after it emerged. In this report we discuss the life cycle of D hominis, the differential diagnosis, and therapeutic approaches.

[Scalp myiasis in an immigrant child]

Myiasis is caused by infestation of the skin by the larvae of flies. This entity has specific epidemiological characteristics. Although it is highly unusual in our environment, imported cases can be found because of increased traveling and immigration. The usual clinical manifestations are subcutaneous abscesses, where the larvae develop. Differential diagnosis includes common disorders such as cellulitis and furunculosis, but knowledge of this entity makes diagnosis and treatment simple. We describe the life cycle of the human botfly and the typical clinical presentation and management of this entity. We also highlight the increasing importance of greater awareness of imported diseases.

Autochthonous furuncular myiasis in the United States: case report and literature review

Most cases of furuncular myiasis in the United States are acquired during travel to other countries. Autochthonous cases are infrequently reported and are most often due to accidental infestation of humans by larvae of flies belonging to the genus Cuterebra, commonly known as "rabbit bot flies" or "rodent bot flies." We describe a case of furuncular myiasis due to Cuterebra larvae in the hand of a patient residing in Wisconsin. The infestation was acquired while the patient gardened near a seepage lake during August. The patient developed papular lesions on the hand and received therapy for presumed bacterial furunculosis, which did not lead to improvement. Retrieval of one of the larvae from the patient permitted identification of the causative agent, and application of an occlusive ointment resulted in complete cure. North American cuterebrid myiasis is rare, and the diagnosis is frequently delayed. Myiasis should be considered when treating patients with refractory furunculosis.