Naturally Occurring Parelaphostrongylus tenuis–Associated Choriomeningitis in a Guinea Pig With Neurologic Signs

Abstract

An adult male guinea pig (Cavia porcellus) with a 1-month history of hind limb paresis, torticollis, and seizures was euthanized and submitted for necropsy. Gross examination was unremarkable, but histologic examination revealed multifocal eosinophilic and lymphoplasmacytic choriomeningitis and cross sections of nematode parasites within the leptomeninges of the midbrain and diencephalon. Morphologic features of the nematode were consistent with a metastrongyle, and the parasite was identified as Parelaphostrongylus tenuis by polymerase chain reaction testing and nucleotide sequencing. Further questioning of the owner revealed that the guinea pig was fed grass from a yard often grazed by white-tailed deer (Odocoileus virginianus). To the authors' knowledge, this is the first report of a naturally occurring P. tenuis infection in a guinea pig.Keywords guinea pig, Parelaphostrongylus tenuis, nervous system, parasitic disease, polymerase chain reaction A 2.5-year-old male guinea pig (Cavia porcellus) was euthanized and submitted for necropsy following a 1-month history of progressive neurologic signs, including hind limb paresis, torticollis, and seizures. Treatment included calcium, vitamin C injections, prednisolone, and buprenorphine. The guinea pig was purchased from a pet store 2 years earlier and was fed a commercial diet supplemented with a variety of fruits and vegetables, including grass from a yard frequented by whitetailed deer (Odocoileus virginianus). For approximately 5 months prior to the onset of clinical signs, the guinea pig was housed with another healthy young male guinea pig. There was no history of trauma.Differential diagnoses for neurologic disease in guinea pigs include trauma, pregnancy toxemia, hypocalcemia, and bacterial otitis/meningitis. Neurologic disease associated with Baylisascaris procyonis migration has been reported in guinea pigs housed on shavings contaminated with raccoon feces. 16 Although neoplastic disease is uncommon in guinea pigs, tumor metastases to the central nervous system (CNS) would be an important differential for an animal with multicentric neurologic deficits, as in this case.A complete necropsy was performed. The calvarium was opened and the brain fixed in situ for sectioning. The entire vertebral column was fixed and decalcified, and representative cross sections were trimmed for histopathology. No gross lesions were detected during the necropsy; however, microscopic examination revealed cross sections of nematode parasites (Fig. 1) within the leptomeninges covering the midbrain, associated with eosinophilic and lymphoplasmacytic choriomeningitis (Fig. 2). The nematodes were 100 to 200 mm in diameter, with a thin, smooth cuticle; coelomyarian musculature; accessory hypodermal chords; and a large gastrointestinal tract composed of few multinucleate cells. Cross sections also contained a genital tract with either sperm or thinshelled eggs. Multifocally, the leptomeninges of the brain and spinal cord and the choroid plexus were expanded by moderate infil...

Novel methods of immunogenic antigen selection for serological diagnosis of Parelaphostrongylus tenuis infection

“…Future studies utilizing experimental infections are crucial to adequately assess the viability of this specific assay for validation purposes. This would require the adaptation of this assay to non-cervid species and could be applied to a guinea pig model capable of natural infection with the parasite 23 , 24 . An alternative to live-animal experiments could be sera sourced from livestock patients that enter our hospital with known infection status.…”

Genetic analyses of the parasitic nematode,Parelaphostrongylus tenuis, in Missouri and Kentucky reveal unexpected levels of diversity and population differentiation

“…Although its definitive host is the white-tailed deer, a number of studies have confirmed that P. tenuis can parasitize many different hosts, including elk, moose ( Alces alces ), llamas ( Lama glama ), alpacas ( Vicugna pacos ), goats ( Capra hircus ), cattle ( Bos taurus ), horses ( Equus caballus ), bison ( Bison bison ), sika deer ( Cervus nippon ) and guinea pigs ( Cavia porcellus ; Anderson, 1972; Lankester, 2001, 2010; Weiss et al ., 2008; Whitehead and Bedenice, 2009; Gerhold et al ., 2010; Tanabe et al ., 2010; Mitchell et al ., 2011; Southard et al ., 2012; Dobey et al ., 2014; Gerhold and Hickling, 2016). To date, the majority of these studies have focused on genetic confirmation of host infection and identification of morphologically indistinguishable dorsal-spined larvae in Elaphostrongyline species (Gajadhar et al ., 2000; Kutz et al ., 2001; Gerhold et al ., 2010; Dobey et al ., 2014).…”

Cerebrospinal nematodosis caused by Parelaphostrongylus species in an adult bull

“…Nested PCR has been used to confirm the presence of Parelaphostrongylus DNA in fixed nervous tissue, and the presence of P. tenuis and related species have been confirmed with sequencing. 4,11,16,17 Previous reports of Parelaphostrongylus spp. infection in cattle are rare, and only reported in calves < 1 y old.…”

“…Nested PCR has been used to confirm the presence of Parelaphostrongylus DNA in fixed nervous tissue, and the presence of P. tenuis and related species have been confirmed with sequencing. 4,11,16,17…”