Neurological manifestations of feline cuterebriasis.
Year: 2010
Type: article
Abstract: Cuterebra species (Diptera: Oestridae) are an often-overlooked cause of central nervous system signs in cats with outdoor access during the summer months. Cuterebra species, of which there are 34 found throughout the Americas, are obligate parasites of rodents and lagomorphs (1,2–5). The female botfly may lay up to several thousand eggs, typically in groups of 5 to 15 per site, along rodent runs, near the opening to the burrow, or within the burrow, depending on the species (2,5). The eggs hatch approximately 1 wk later in response to a sudden rise in temperature, such as the hot breath of a passing host (3–5). Depending on environmental conditions, eggs may remain viable for 6 to 10 mo, resulting in late season infections (5). The moist larva sticks to the fur and achieves entry to the body via the mucous membranes of a natural orifice (2–4). The larva migrates extensively through the host, visiting the trachea, thoracic and abdominal cavities, before arriving at its preferred subcutaneous site (2–4). Here it feeds on local tissues, creating, 3 to 4 wk after initial infection, a local swelling (a warble) with a breathing/excretion pore, and molts through the various larval instar stages (2–4). Three to 8 wk after entering the host, the larva backs out through the pore, drops to the ground, and burrows into the soil to pupate and, possibly, overwinter (2–4). Emergence of the adult botfly from the pupa may vary from a month to several years later, starting in late spring (2–4). Given 1 to 2 wk for mating, 1 wk for egg maturation, and 3 to 4 wk for larval migration and warble development, the seasonal (midsummer through fall) occurrence of cuterebral myiasis becomes apparent (2).
Cats are an atypical host, and are speculated to acquire infection while exploring rodent and rabbit environs (2). It has been suggested that cats are not susceptible to rodent-infesting Cuterebra species, instead acquiring the lagomorph-infesting species (6). Cats in published case reports are young to middle-aged and, in Canada, they present in the months of July, August, and September (2,7–9). Clinical signs depend on the migration path of the larva. Most commonly, the cutaneous form is encountered — this is relatively benign and easily diagnosed and treated (2,10). There are case reports of feline ophthalmomyiasis (11–14). Similarly, Cuterebra has been reported in the trachea (15,16), pharynx (17), and upper respiratory tract (7,18). Intracranial cuterebral myiasis may be preceded by upper respiratory signs (2,7,19), with the larvae gaining access to the calvarium via the cribriform plate, middle ear, or other foraminae (7–9,20). Rarely, multiple larvae may be found in an individual animal (8). Larvae removed from their hosts do not pose a zoonotic threat (2,8,10).
Clinical signs associated with cerebrospinal cuterebriasis are a reflection of the neuroanatomical extent of the lesion(s) caused by the larva. As such, clinical signs may include acute status epilepticus, unilateral or bilateral central blindness, abnormal behavior, head pressing, anorexia, lethargy, disorientation, dementia, abnormal vocalization, circling, vestibular or other cranial nerve deficits, abnormal gait, postural reactions, or reflexes, and inappropriate responses to stimulation (2,7,8,12,19). Thus, lesion localization within the central nervous system may include any or all of the thalamocortex, brainstem, or spinal cord, depending on the larval path. The following 3 cases, seen recently at the Ontario Veterinary College, serve as good illustrations of the variety of clinical signs that may be observed in cats with presumptive or definitive cerebrospinal cuterebriasis.
Source: PubMed
Authors: Fiona M K James, Roberto Poma
Language: English
Subfield: Parasitology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W1714008231