Cuterebriasis is a

parasitic disease A parasitic disease, also known as parasitosis, is an infectious disease caused by parasites. Parasites are organisms which derive sustenance from its host while causing it harm. The study of parasites and parasitic diseases is known as parasitol ...

affecting

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

lagomorph The lagomorphs () are the members of the taxonomic order Lagomorpha, of which there are two living families: the Leporidae (rabbits and hares) and the Ochotonidae ( pikas). There are 110 recent species of lagomorph, of which 109 species in t ...

s (

hare Hares and jackrabbits are mammals belonging to the genus ''Lepus''. They are herbivores and live Solitary animal, solitarily or in pairs. They nest in slight depressions called forms, and their young are precociality, able to fend for themselves ...

rabbit Rabbits are small mammals in the family Leporidae (which also includes the hares), which is in the order Lagomorpha (which also includes pikas). They are familiar throughout the world as a small herbivore, a prey animal, a domesticated ...

pika A pika ( , or ) is a small, mountain-dwelling mammal native to Asia and North America. With short limbs, a very round body, an even coat of fur, and no external tail, they resemble their close relative the rabbit, but with short, rounded ears. ...

s),

felines Feline may refer to: Zoology * Loosely, Felidae, a member of the cat family, which includes the subfamilies Pantherinae and Felinae (conventionally designated a felid). ** Following the taxonomic convention, Felinae, the subfamily of Felidae that ...

, and canines. The etiologic agent is the larval development of

botflies Botflies, also known as warble flies, heel flies, and gadflies, are flies of the family Oestridae. Their larvae are internal parasites of mammals, some species growing in the host's flesh and others within the gut. ''Dermatobia hominis'' is t ...

within the ''

Cuterebra ''Cuterebra'', or rodent bots, is a genus of bot flies that attack rodents and similar animals. Etymology The genus name ''Cuterebra'' is a blend of the Latin words ''cutis'' 'skin' and ''terebra'' 'borer' with apparent shortening of expected ' ...

'' or '' Trypoderma'' genera, which occurs obligatorily in rodents and lagomorphs, respectively. Felines and canines serve as accidental hosts, but research suggests only by ''Trypoderma'' spp. Entrance into the body by first-

instar An instar (, from the Latin '' īnstar'' 'form, likeness') is a developmental stage of arthropods, such as insects, which occurs between each moult (''ecdysis'') until sexual maturity is reached. Arthropods must shed the exoskeleton in order to ...

larvae occurs via mucous membranes of natural orifices or open wounds as opposed to direct dermic penetration.

Clinical signs

In rabbits, hares, and lagomorphs, clinical signs usually do not appear. Subcutaneous cysts, warbles, may present upon larval deposition out of the body at maturation. Three forms in which cuterebriasis may present in canines and felines: * Myasis involves subcutaneous cyst formation due to third larval-instar maturation, occurring about 30 days after entry into the body. Cysts are often found on the face, neck, and trunk, but location varies with larval migration within the host. Serous discharge may be observed from these cysts, which are typically 3-5 mm in diameter and include a central pore through which the larvae respire. This pore also serves as a means of exit for the larvae, which occurs between 3 and 8 weeks after entry., p. 213. * Cerebrospinal cuterebriasis results from larval migration to the brain. This is seen in cats, and is the proposed cause for feline ischemic encephalopathy and a suggestive causative agent of feline idiopathic vestibular disease. Symptoms of this type of presentation include lethargy, seizures, blindness, abnormal vocalization or gait, circling, and abnormal or no reflex responses. When affecting the central nervous system, cats are known to exhibit violent sneezing attacks that can begin weeks prior to manifestation of other clinical signs. * Respiratory disease results when larval migration occurs through the trachea, pharynx, diaphragm, or lungs. Cuterebriasis has been increasingly noted as a cause for dyspnea in felines.

Diagnosis

Definitive diagnosis can only occur with positive identification of the larvae. This involves radiologic imaging (preferably

MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and rad ...

, which can reveal larval migration tracks and in some cases the larvae themselves), as well as surgical exploration during which larvae can be removed and examined for identification. Identification of exact species is often impossible, as the instars of the various ''Cuterebra'' and ''Trychoderma'' spp. exhibit significant resemblance, but identification as a ''Cuterebra'' botfly is sufficient for diagnosis as cuterebriasis. Typically, a third larval-instar is found and identifiable by its dark, thick, heavily spined body.

Treatment

Subcutaneous cysts may be surgically opened to remove less-mature bots. If matured, cysts may be opened and ''Cuterebra'' may be removed using mosquito forceps. Covering the pore in petroleum jelly may aid in removal. If larvae are discovered within body tissues, rather than subcutaneously, surgical removal is the only means of treatment.

Ivermectin Ivermectin is an antiparasitic drug. After its discovery in 1975, its first uses were in veterinary medicine to prevent and treat heartworm and acariasis. Approved for human use in 1987, it is used to treat infestations including head lice ...

may be administered with

corticosteroid Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are invo ...

s to halt larval migration in cats presenting with respiratory cuterebriasis, but this is not approved for use in cats. A cure for cerebrospinal cuterebriasis has not been reported.

Clinical signs

Diagnosis

Treatment

References

Further reading