Immunodiagnosis of experimental Parelaphostrongylus tenuis infection in elk

Elk infected with the meningeal worm, Parelaphostrongylus tenuis (Protostrongylidae), do not consistently excrete larvae in feces, making the current method of diagnosing live animals using the Baermann fecal technique unreliable. Serological diagnosis could prove more useful in diagnosing field-infected animals but depends on the identification and availability of good quality antigen. To mimic field infections, 2 elk were inoculated with 6 infective L3 larvae of P. tenuis, and another 2 with 20 L3 larvae. Fecal samples were examined for nematode larvae using the Baermann technique and serum samples taken were tested for anti-P. tenuis antibody with ELISAs by using the excretory-secretory (ES) products of L3, and sonicated adult worms as antigens. One animal passed first-stage larvae in its feces 202 days postinoculation, but passed none thereafter. The remaining 3 inoculated animals did not pass larvae. In contrast to parasite detection, antibodies against larval ES products were detected in all animals starting from 14 to 28 days postinoculation and persisted until the termination of the experiment on day 243 in 2 animals that harbored adult worms. Antibodies against somatic antigens of the adult worm were not detected until day 56 but also persisted until the end of the experiment in the animals with adult worms. In 2 elk that had no adult worms at necropsy, anti-ES antibodies were detected transiently in both, while anti-adult worm antibodies were present transiently in one. These findings confirm the superiority of P. tenuis larval ES products over somatic adult worm antigens as serodiagnostic antigens, as previously observed in studies of infected white-tailed deer, and extend the application of the newly developed ELISA test in diagnosing and monitoring cervids experimentally infected with P. tenuis.     

Clinical Parelaphostrongylus tenuis infection in two captive American bison (Bison bison)

CASE DESCRIPTION: 2 juvenile (17 and 19 months of age) male American bison (Bison bison) were examined because of acute bilateral hind limb weakness and ataxia; 1 animal also had urinary incontinence. TREATMENT AND OUTCOME: Given the clinical signs and rapid deterioration in the condition of these 2 animals, obtaining a definitive diagnosis was considered essential to minimizing the risk of disease in the remaining bison herd and among other animals at the facility. Therefore, both affected animals were euthanized. At necropsy, no gross abnormalities were seen. Histologic examination of sections of the brains from both animals revealed mild to moderate multifocal aggregates of eosinophils and mononuclear cells in perivascular regions of the meninges and gray matter of the cerebrum, cerebellum, and brainstem. Systematic examination of multiple sections of brain and spinal cord revealed evidence of nematode sections and aberrant parasite migration. CLINICAL RELEVANCE: Findings suggested that CNS migration of Parelaphostrongylus tenuis in American bison may cause clinical signs. These findings have implications for the management of captive bison and free-ranging bison sharing ranges with white-tailed deer (Odocoileus virginianus), the definitive host, and elk (Cervus elaphus canadensis).     

Parelaphostrongylus tenuis in captive reindeer and sable antelope

Parelaphostrongylus tenuis caused neurologic disease in 6 reindeer (Rangifer tarandus tarandus) and 2 sable antelope (Hippotragus niger) that were housed at the National Zoological Park Conservation and Research Center in Front Royal, Va. Progressive hindlimb ataxia and weakness were seen in all affected animals. The parasite was recovered from the subdural space of one reindeer and was seen histologically within the neuropil of another reindeer and a sable antelope. In the other reindeer and sable antelope, diagnoses of parelaphostrongylosis were based on clinicoepidemiologic findings and microscopic lesions. Because parelaphostrongylosis is a density-dependent disease and because the number of white-tailed deer probably will increase, the incidence of P tenuis infections in domestic and nondomestic animals probably will increase as well. Zoos and wildlife parks especially should be cautious when introducing exotic hoofstock to areas with Parelaphostrongylus tenuis-infected white-tailed deer.     

Intraocular nematodiasis caused by Parelaphostrongylus tenuis in an eland antelope (Taurotragus oryx).

A 10-mo-old female eland (Taurotragus oryx) at the Wilds exhibited recalcitrant, progressive unilateral uveitis for a 5-wk period, despite constant medical treatment. Unilateral enucleation was performed because of blindness and animal discomfort evidenced by continuous blepharospasm. Histopathologic examination of the eye demonstrated intraocular larvae morphologically consistent with Parelaphostrongylus tenuis, the first known case of intraocular P. tenuis migration. This animal subsequently was euthanatized because of severe, nonresponsive neurologic signs associated with P. tenuis infection.     

Parelaphostrongylus tenuis Cerebrospinal Nematodiasis in a Horse with Cervical Scoliosis and Meningomyelitis

There are reports of horses with acute onset acquired cervical scoliosis and cutaneous analgesia. The underlying dorsal gray column myelitis that produces these neurologic signs has been only presumptively attributed to migration of Parelaphostrongylus tenuis within the spinal cord. Despite previous confirmation brain by polymerase chain reaction testing, of P. tenuis within the brain of horses by polymerase chain reaction testing, genetic testing has failed to definitively identify the presence of this parasite in cases of equine myelitis. This case report provides molecular confirmation via polymerase chain reaction of P. tenuis within the cervical spinal cord of a horse with scoliosis and cutaneous analgesia.     

Evaluation of excretory-secretory products and somatic worm antigens for the serodiagnosis of experimental Parelaphostrongylus tenuis infection in white-tailed deer.

Three different antigen preparations of Parelaphostrongylus tenuis were assessed for their effectiveness in an indirect enzyme-linked immunosorbent assay (ELISA) to diagnose experimental infection of white-tailed deer (WTD). The antigen preparations were the excretory-secretory products of third-stage larvae (ES-L3), somatic antigens of third-stage larvae (sL3), and somatic antigens of the adult stage (sA) of P. tenuis. The relative sensitivities of the antigen preparations in indirect ELISA were ES-L3 > sL3 > sA. Immunoglobulin G (IgG) antibodies to ES-L3 and sL3 could be detected 14 days postinfection and were consistently present in all infected animals from the first month to the end of the experiment at 5 months. In contrast, IgG antibodies to sA could not be detected at any time in 2 infected WTD. ES-L3 and sL3 proved reliable in the early detection of anti-P. tenuis antibodies and in the serological monitoring of experimentally infected animals. Significant cross-reactivity between all P. tenuis antigen preparations and sera from animals infected with parasites other than P. tenuis may preclude their use for field diagnosis. Nevertheless, isolation of unique P. tenuis antigen(s) should lead to the development of a specific serological test for infected white-tailed deer.     

Evidence of Parelaphostrongylus tenuis infections in free-ranging elk (Cervus elaphus) in southern Ontario

The antemortem detection of a Parelaphostrongylus tenuis infection in a free-ranging wild elk (Cervus elaphus) in southern Ontario is documented. Postmortems on other free-ranging elk that died during 2000-2005 indicated that 59% (17/29) were infected with P. tenuis, based on presence of lesions in the brain.     

Lymphosarcoma in an alpaca

A 16-month-old, female alpaca presented with a 24-hour history of anorexia and depression. On necropsy, it was found that the liver was grossly enlarged and the cortices of both kidneys contained multifocal lesions. Histologic examination of these lesions and other tissues revealed infiltration with lymphocytic cells, a finding consistent with lymphosarcoma.     

Sarcoptes scabiei infection on an alpaca (Lama pacos)

Abstract

Extract

Sarcoptes scabiei has been reported on a number of hosts in New Zealand including the dog, ferret (Mustela putorius), pig, hedgehog (Erinaceus europaeus), llama (Lama glama) and human (Tenquist and Charleston 2001 Tenquist, JD and Charleston, WAG. 2001. A revision of the annotated checklist of ectoparasites of terrestrial mammals in New Zealand. Journal of the Royal Society of New Zealand, 31: 481–542. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]). We report here the first record of infestation with these mites on an alpaca (Lama pacos) in New Zealand. The mites were detected on an adult male alpaca that had been maintained for several years along with others on a property in the Wairarapa region of the North Island. The infestation manifested itself as pruritis and alopecia. On clinical examination thick, grey, hyperkeratotic crusts were visible firmly adherent to the skin of the medial surface of both hindlegs. Similar smaller and possibly more recent lesions were also evident on the animal's face, which appeared to be the only affected alpaca on the property.     

Severe biliary hyperplasia associated with liver fluke infection in an adult alpaca

An adult alpaca (Lama pacos) had a locally extensive area of hepatic atrophy involving the right lobe. Grossly, the atrophic lobe was light tan and firm and contained small, raised, white to yellow, partially mineralized circular nodules predominantly at the periphery of the atrophic tissue. Microscopically, viable hepatocytes were not present in the atrophic area, and the tissue consisted of diffuse biliary epithelial proliferation without any evidence of nuclear or cellular atypia or the presence of mitotic figures. The circular mineralized nodules consisted of granulomatous inflammation with intralesional parasitic ova surrounded by fibrous connective tissue. Morphologically, the ova were compatible with those of Fasciola hepatica. The severe biliary hyperplasia was unusual, and it was not clear whether it was caused by an aberrant host response to the parasitic infection or whether it was an unrelated event.     

Intraocular melanoma in an alpaca

A case of primary intraocular melanoma in an alpaca is reported. This patient also presented with a mild normocytic, normochromic anemia and hypoproteinemia. These can be markers of an immunodeficiency syndrome associated with llamas. Although this patient did not appear to have clinical signs of this syndrome, its presence needed to be ruled out as animals affected with this syndrome are subject to recurrent severe debilitating diseases and death. To our knowledge, intraocular melanoma has not been previously reported in an alpaca.     

Splenic torsion in an alpaca

OBJECTIVE: To describe the clinical signs, diagnostic evaluation and surgical management of an alpaca with splenic torsion. ANIMALS: Six-year-old female alpaca. RESULTS: Splenic torsion and uterine torsion were the inciting cause for persistent abdominal discomfort in this alpaca. Rectal examination, abdominocentesis, and transabdominal ultrasonographic findings were suggestive of a splenic lesion. Surgical management involved splenectomy of a necrotized spleen. CONCLUSIONS: Although rare in occurrence, splenic torsion should be considered as a potential cause of abdominal discomfort in alpacas. Splenectomy is a reasonable and successful method of treatment for a devitalized spleen secondary to splenic torsion in alpacas. CLINICAL RELEVANCE: Splenic torsion causes persistent abdominal discomfort in camelids and may be associated with uterine torsion. Rectal examination, transabdominal ultrasound and abdominocentesis are useful diagnostic tools to differentiate splenic torsion from other causes of abdominal discomfort. Splenectomy is an uncomplicated procedure in camelids and has a favorable prognosis.     

Urogenital leiomyosarcoma in an alpaca

A mass in the pelvic canal of a 4-year-old pregnant alpaca hembra diagnosed as leiomyosarcoma of the urogenital tract was confirmed by biopsy. Following a tube cystotomy, the alpaca was presented 33 d later, 2 d after the tube cystotomy had been dislodged. A dead cria was delivered by caesarean section.