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Llama ( Lama glama ). A , cerebrocortical gray matter. Cross-section of an adult male Parelaphostrongylus tenuis with a large intestine (i) composed of few, multinucleate cells; a genital tract (g) containing sperm; accessory hypodermal cords (c); and polymyarian– coelomyarian musculature (m). Hematoxylin and eosin (HE). Bar = 50 μm. B , cervical spinal cord. Migration tracts are characterized by multifocal, random areas of rarefaction; spongiform change; gliosis with gitter cells; and axonal degeneration with frequent spheroids (*). HE. Bar = 100 μm.
Source publication
Aberrant migration of Parelaphostrongylus tenuis in camelids results in neurologic deficits, recumbency, and sometimes death. An antemortem diagnosis of P. tenuis in camelids is typically based upon the presence of characteristic asymmetric neurologic deficits, known exposure to white-tailed deer, cerebrospinal fluid (CSF) eosinophilia, and respons...
Context in source publication
Context 1
... cases were excluded due to severe blood contami- nation in the CSF, complicating cytologic interpretation. Diagnosis of P. tenuis was made in 35% (13/37) of the cases, based on characteristic histologic findings of migratory tracts in 100% (13/13) and observation of a metastrongylid nematode within the spinal cord segments in 31% (4/13) of cases (Fig. 1A, 1B). Two of the camelids with larvae seen on cross-section of the spinal cord had no known anthelmintic administration prior to or during hospitalization. The came- lids in the P. tenuis group had a median age of 4 years (range: 4 months to 10 years) and 92% female distribution (12 females, 1 male). Presenting neurological deficits in the ...
Citations
... tenuis; meningeal worm) cerebrospinal nematodiasis. 2 Additionally, several common neurologic disease processes in camelids produce characteristic changes in CSF, such as neutrophilic pleocytosis with bacterial meningitis and mononuclear pleocytosis with listeriosis. 3,4 In most cases, CSF can be obtained easily from the lumbosacral space without sedation, using a local anesthetic. ...
Background
Cerebrospinal fluid (CSF) is commonly analyzed in South American camelids with suspected neurologic disease because of ease of collection and characteristic findings associated with certain diseases.
Objectives
To assess CSF findings associated with short‐term survival or non‐survival in South American camelids in which neurologic disease was a differential diagnosis based on history and physical examination.
Animals
Twenty‐one llamas and 33 alpacas that underwent CSF analysis at the University of Missouri Veterinary Health Center.
Methods
Retrospective study. Medical records of camelids that underwent CSF analysis between January 2005 and September 2021 were studied. Short‐term survival was defined as survival to discharge from the Veterinary Health Center. A Fisher's exact test was used to compare species, CSF results, and survival.
Results
Odds of survival were 3.9 times higher in camelids with a total nucleated cell count (TNCC) <3 cells/μL (P = .04). No significant association was found between survival and total protein concentration (TPC; P = .15) or percentage of eosinophils (P = 1.0). No significant correlation was found between species and increased TNCC (P = .63), TPC (P = .55), or percentage of eosinophils (P = .30). Among camelids diagnosed with Paralephostrongylus tenuis infestation, odds of survival were 4.95 times higher in alpacas (P = .05).
Conclusions
Cerebrospinal fluid TNCC ≥3 cells/μL is associated with decreased odds of short‐term survival in South American camelids.
... Definitive diagnosis is made by identifying the nematode in the brain and/or spinal cord during necropsy or histopathology (7) and is otherwise assumed based on a combination of neurological signs and characteristic histological changes associated with nematode migration in the central nervous system (2,9). Antemortem diagnosis is presumptive based on clinical signs and evidence of a marked increase in eosinophils in the cerebrospinal fluid (if sampled), though identification of the nematode is rare (7,10). ...
Meningeal worm, or Parelaphostrongylus tenuis (P. tenuis) is a nematode parasite that can invade the nervous system of small ruminant and camelid species such as alpaca, llama, goats and sheep. Limited reports exist on the epidemiology of disease caused by the nematode in susceptible livestock. We examined archived necropsy reports from small ruminant and camelid mortalities that were submitted, post mortem, to the University of Minnesota Veterinary Diagnostic Laboratory (MNVDL) during 2001–2019 for gross necropsy, histopathology, and pathogen screening. We estimated P. tenuis-induced mortality over time and developed temporal models to better understand patterns and drivers of P. tenuis-induced mortalities in these animals. During the period under examination, 5,617 goats, sheep, llamas and alpacas were necropsied, revealing an overall P. tenuis-induced mortality rate of 1.14% in the necropsy submission pool for these species. P. tenuis-induced mortality rates were highest in llamas (9.91%) and alpacas (5.33%) compared to sheep and goats (<1%), with rates in llamas and alpacas significantly higher than in sheep and goats. P. tenuis-induced mortalities exhibited one seasonal peak, around October to December. P. tenuis-induced mortality rates varied greatly between years, and have significantly increased over time. We also observed a positive correlation between summer temperature (range 20.4–22.4°C) and P. tenuis-induced mortality rates (range 0–3.9%), but not precipitation. This study demonstrates seasonal patterns and differences in mortality between alpacas, goats, llamas and sheep and helps us to better understand the epidemiology of P. tenuis mortality.
... 8,10 To date, the only antemortem test suggestive of P. tenuis in patients with compatible clinical signs is cerebrospinal fluid (CSF) analysis, and affected animals typically have eosinophilic pleocytosis. 4,11,13 Definitive diagnosis has relied on autopsy, with identification of the nematode or characteristic tissue changes histologically, although PCR has become increasingly useful in reaching a diagnosis. ...
... Eosinophilic pleocytosis of CSF in camelids is considered a sensitive laboratory test for P. tenuis and is reported in acute cases of infection in cattle. 11,13 Postmortem diagnosis of nematodosis has previously relied on identification of larvae or compatible histopathologic changes. 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. ...
A 2-y-old Brahman bull was presented with progressive hindlimb ataxia and paraparesis that led to recumbency. Postmortem examination revealed scattered pinpoint, red-brown foci within the brainstem and gray matter of the spinal cord, and a larger lesion within the spinal cord at the level of T13. Histology of the section of T13 contained cross-sections of nematodes consistent with Parelaphostrongylus tenuis. Evidence of inflammation was present in other affected areas of the spinal cord and brain. DNA extraction and nested PCR were performed, which demonstrated 98% identity and 100% coverage to both P. tenuis and P. andersoni. Our case highlights the utility of DNA sequencing in parasite identification.
... Larvae released from the gastropods penetrate the abomasum wall and migrate to the dorsal grey columns of the spinal cord over a minimum of 49 days. 8 It is important to note that while it is commonly considered that larvae migrate to the spinal cord they can travel to other regions of the central nervous system. In horses, larvae have been documented to travel to the spinal cord, cerebrum, midbrain, pons and medulla oblongata. ...
A nine-month-old Boer Buck presented for an acute onset of pelvic limb ataxia. Radiographs, complete blood count and serum biochemistry were within normal limits. A cerebrospinal fluid analysis yielded an eosinophilic pleocytosis, consistent with cerebrospinal nematodiasis. Treatment with ivermectin, non-steroidal anti-inflammatories, fenbendazole and range of motion exercises resulted in partial recovery of pelvic limb function within five days. Within five months post treatment the buck’s ambulation had returned to a normal gait.
... However, in only one of the cases with parasitic encephalopathy in this study were lesions present in the brain but not elsewhere in the CNS. A recent study focused on the diagnostic sensitivity and specificity of CSF analysis for the clinical diagnosis of Parelaphostrongylus tenuis infestation [24]. In that study, the authors reported that CSF having > 17% eosinophils had a sensitivity of 85% and specificity of 92% for P. tenuis and when eosinophils concentration was > 1.4 eosinophils/uL that the sensitivity was 85% and specificity was 96%. ...
Objective: To review neurological disease in llamas and alpacas.
Design: Retrospective study.
Sample Population: All cases of neurological disease in llamas and alpacas presenting between February 1993 and October 2003. Procedures: Medical records database analysis.
Results: Medical records of each occurrence of neurologic signs in 181 South American Camelids admitted on 185 occasions (90 alpacas and 95 llamas) were evaluated. Age ranged from 0 days to 20 years, but 70.5% of cases were ≥ 1 year old. Specific clinical diagnosis was achieved by cerebrospinal fluid analysis (CSF), radiographs, computed tomography, laboratory testing, or necropsy in 74% of cases. 54% of cases survived; 46% of cases died or were euthanized. The most common diagnosis (31%) was parasitic myelopathy/encephalopathy (PME). CSF eosinophilia ≥10% was found in 85% of parasitic spinal migrations but only in 55% of intracranial migrations, and 73% had increased protein in CSF. There was a seasonal bias for PME with 79% of cases occurring between October and March. Survival of PME cases was 77% for spinal migration but only 7% when intracranial migration occurred. The most common diagnoses, excluding PME, were infectious disease (15%) and trauma (12%). Most trauma cases involved the cervical spine of which 50% survived.
Conclusion and Clinical Relevance: Neurological disease is common in llamas and alpacas. The differential diagnoses list should be adjusted for patient age and seasonal influences. CSF analysis and computed tomography are useful diagnostic tools to differentiate causes of neurologic disease in llamas and alpacas.
Keywords: Llama, Alpaca, Neurologic disease, Brain, Spinal cord
List of Abbreviations: CK: Creatine kinase; CNS: Central nervous system; CSF: Cerebrospinal fluid; CT: Computed tomography; EHV-1: Equine herpesvirus-1; PME: Parasitic myelopathy/encephalopathy
... [6][7][8] The geographical distribution of the disease relies on the presence of both hosts in the same location. Although the disease is mainly found in eastern North America, 9,10 it has been reported in areas of central North America as well. 3,[11][12][13] Clinical signs of CN typically reflect spinal cord involvement and include a wide-based hind limb stance, ataxia that often is worse in the hind limbs than in the forelimbs, and recumbency in later stages. ...
... Although there is no definitive antemortem test for CN, the majority of affected camelids have eosinophilic pleocytosis of cerebrospinal fluid (CSF). 9 Although the presence of eosinophilic pleocytosis in camelids presenting with neurologic signs does not definitively diagnose CN, the paucity of other diseases that induce CSF eosinophil production allow CSF analysis to presumptively diagnose CN in most cases. In a retrospective study, only 8% of camelids presenting with neurologic signs and CSF eosinophilic pleocytosis were not diagnosed with CN (1 was diagnosed with Toxoplasma gondii and a conclusive diagnosis was not made for the other camelid). ...
... In a retrospective study, only 8% of camelids presenting with neurologic signs and CSF eosinophilic pleocytosis were not diagnosed with CN (1 was diagnosed with Toxoplasma gondii and a conclusive diagnosis was not made for the other camelid). 9 A CBC and serum biochemical analysis (SBA) often are reported to be unremarkable, but the majority of available reports are from experimental infection with P. tenuis, describe a single case, or are anecdotal. 4,5 Definitive diagnosis of CN requires observation of nematodes within the CNS at postmortem examination, but histologic findings of migratory tracts are consistent with infection. ...
Background:
Information about the clinical and clinicopathologic aspects of cerebrospinal nematodiasis (CN) in camelids is limited.
Hypothesis:
Clinical and therapeutic variables will be identified as factors predictive of survival.
Animals:
Client-owned camelids suspected of having CN admitted to Purdue University between 1995 and 2015.
Methods:
A retrospective study was performed. A diagnosis of CN was based on cerebrospinal fluid (CSF) eosinophilic pleocytosis or postmortem findings.
Results:
Eleven alpacas and 9 llamas met the inclusion criteria. Seventy-five percent of the camelids were male (27% castrated and 73% intact). Common clinical abnormalities included proprioceptive deficits (100% of animals), recumbency (55%), tachypnea (55%), and ataxia (40%). Among the 85% of treated animals, 100% received PO fenbendazole, and 88% received a nonsteroidal anti-inflammatory drug. The survival rate to discharge was 45%. Plasma fibrinogen concentration, creatine kinase activity, and serum creatinine concentration were significantly higher in nonsurvivors. Blood eosinophil count, platelet count, and total CO2 were significantly lower in nonsurvivors. Factors associated with survival were species, sex, absence of treatment with corticosteroids, and clinical improvement. There was no association between recumbency at admission and survival. A plasma fibrinogen concentration above >266 mg/dL was an excellent diagnostic test to predict survival in the presence of neurological signs or CSF eosinophilia.
Conclusions:
Although prognosis for CN in camelids is guarded, presence of recumbency at admission is not predictive of nonsurvival. Male camelids and llamas appear more likely to die from CN. Corticosteroid treatment is contraindicated in animals diagnosed with CN.
... Most diagnoses are based on clinical signs, antemortem detection of high levels of eosinophils in cerebrospinal fluid, and response to treatment with anthelmintics and nonsteroidal anti-inflammatory drugs. 14,15 The likelihood of finding a nematode during gross necropsy and/or histology is remote, and therefore diagnoses are often inconclusive. Histologic lesions of the central nervous system (CNS), that characterize P. tenuis infection are similar to Baylisascaris procyonis in human, nonhuman primate, and avian hosts and include axonal degeneration and swelling, perivascular cuffing, the presence of hemosiderin-laden macrophages, and increased numbers of eosinophils. ...
Formalin-fixed, paraffin-embedded tissues from elk (Cervus elaphus), goats, and camelids with case histories and lesions suggestive of Parelaphostrongylus tenuis were examined by histology to characterize lesions that could aid in definitively diagnosing P. tenuis infection. Additionally, sections of paraffin-embedded tissue were used in a nested polymerase chain reaction (nPCR) using Parelaphostrongylus-specific primers to determine how PCR results corresponded with histological findings. Histological changes in brain and spinal cord consisted of linear tracks of hemorrhage; tracks or perivascular accumulations of hemosiderin-laden macrophages; acute foci of axonal degeneration and/or linear glial scars; and perivascular, parenchymal, or meningeal accumulations of eosinophils and/or lymphocytes and plasma cells. Of the 43 samples with histologic lesions consistent with neural larval migrans, 19 were PCR positive; however, only 8 were confirmed Parelaphostrongylus by DNA sequencing. Additionally, 1 goat was identified with a protostrongylid that had a 97% identity to both Parelaphostrongylus odocoilei and a protostrongylid nematode from pampas deer (Ozotoceros bezoarticus celer) from Argentina. None of the histologic lesions individually or in combination correlated statistically to positive molecular tests for the nematode. The results indicate that it is possible to extract Parelaphostrongylus DNA from formalin-fixed, paraffin-embedded tissue, but extended fixation presumably can cause DNA crosslinking. Nested PCR provides another diagnostic tool to identify the cause of neurologic disease in camelids and elk with histologic lesions consistent with neural larval migrans. Furthermore, potential novel protostrongylid DNA was detected from a goat with lesions consistent with P. tenuis infection, suggesting that other neurotropic Parelaphostrongylus species may occur locally.
... 8,10 To date, the only antemortem test suggestive of P. tenuis in patients with compatible clinical signs is cerebrospinal fluid (CSF) analysis, and affected animals typically have eosinophilic pleocytosis. 4,11,13 Definitive diagnosis has relied on autopsy, with identification of the nematode or characteristic tissue changes histologically, although PCR has become increasingly useful in reaching a diagnosis. ...
... Eosinophilic pleocytosis of CSF in camelids is considered a sensitive laboratory test for P. tenuis and is reported in acute cases of infection in cattle. 11,13 Postmortem diagnosis of nematodosis has previously relied on identification of larvae or compatible histopathologic changes. 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. ...
The classic Lyme borreliosis (LB) cycle, involving the vector Ixodes scapularis and the etiological agent Borrelia burgdorferi sensu stricto (Bbss), has been well documented in the Northeastern US, where this disease is becoming increasingly prevalent in humans and dogs. In the Western US, the LB cycle involves two tick species: Ixodes spinipalpis (critical for sylvatic cycles of the pathogen) and I. pacificus (the primary vector to humans). Recently, in coastal regions of North Carolina, I. affinis has been shown to have a higher incidence of Borrelia burgdorferi sensu lato (Bbsl) than does I. scapularis. This raises the possibility that LB in the Southeastern US involves multiple tick species, with I. affinis maintaining Bbsl in sylvatic cycles similar to those seen in the West. I. affinis is not known to be a human-biting tick, so the shift from an Ixodes scapularis-dominated LB cycle in the northeast to an I. affinis-dominated cycle in the Southeast may help explain the low prevalence of LB cases in southeastern states. Nevertheless, other Ixodid tick species in the Southeast, such as I. angustus and I.minor, do occasionally parasitize human hosts, so low-level LB transmission is a possibility in southeastern states if there are sylvatic cycles of Bbsl involving I. affinis. Changes in prevalence of Bbss in I. scapularis and I. affinis along a North-South gradient from southern Virginia into South Carolina will be described, and their potential implications for Lyme disease risk in humans and canines will be discussed.
This retrospective study describes clinical presentation, diagnostic approach, treatment, and outcome for goats with presumptive cerebrospinal nematodiasis. A presumptive diagnosis was made based on neurologic signs, results of cerebrospinal fluid analysis, and response to treatment. Six goats were identified that met inclusion criteria. Cerebrospinal fluid analysis revealed eosinophilic pleocytosis (total nucleated cell count: 12 to 430/μL, 33 to 89% eosinophils). All 6 goats were treated with fenbendazole and anti-inflammatory drugs (NSAIDs ± corticosteroids) and 4 received physical rehabilitation therapy. At discharge or follow-up, all 6 goats were ambulatory and had minimal neurologic deficits. Key clinical message: In goats, cerebrospinal nematodiasis caused by Parelaphostrongylus tenuis is often a presumptive diagnosis based on neurologic signs, shared habitat with white-tailed deer, eosinophilic pleocytosis, and response to anthelmintic therapy. Presumptive cases in goats have many similarities to confirmed cases in camelids. Further study is indicated to characterize the clinical signs and optimize the diagnosis and treatment of goats infected with P. tenuis.
