Analysis of heavy-chain antibody responses and resistance to Parelaphostrongylus tenuis in experimentally infected alpacas

Epidemiological Investigation of Meningeal Worm-Induced Mortalities in Small Ruminants and Camelids Over a 19 Year Period

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.

A RETROSPECTIVE SUMMARY OF CERVID MORBIDITY AND MORTALITY IN ONTARIO AND NUNAVUT REGIONS OF CANADA (1991-2017)

Free-ranging cervids in Canada face diverse threats such as climate change, human population expansion, and the northward spread of vector-borne pathogens. However, we currently have a limited understanding of the impacts of these health challenges in Ontario cervids. Our objective was to identify and characterize causes of morbidity and mortality in free-ranging cervids submitted to the Ontario and Nunavut node of the Canadian Wildlife Health Cooperative (CWHC) over a 27-yr period (1991 to 2017). Submissions included carcasses submitted for full postmortem examination (gross and histopathology; n=196) and field-collected tissues (n=384). Ancillary tests were performed on a case-by-case basis. Univariable logistic regression was used to test for associations between select causes of morbidity and mortality, and factors such as sex, age, and season. Four cervid species were examined: white-tailed deer (Odocoileus virginianus; n=211), moose (Alces alces; n=140), elk (Cervus canadensis; n=136), and caribou (Rangifer tarandus caribou; n=93). Noninfectious disease was the most common general cause of morbidity and mortality (38.1%; 221/580) and was most commonly attributed to trauma (49.7%; 110/221). Deaths attributed to infectious diseases (34.3%; 199/580) were most often bacterial in etiology (45.7%; 91/199). The most common primary infectious disease diagnosed in caribou was digital limb infection, and moose were most commonly diagnosed with parasitic causes, including meningeal worm (Parelaphostrongylus tenuis) and winter tick (Dermacentor albipictus). Chronic wasting disease was not diagnosed among cervids tested during the study period, consistent with the previous lack of detection of the disease in Ontario. These results reveal that anthropogenic, infectious, and environmentally associated causes of morbidity and mortality are commonly diagnosed in cervids submitted to the CWHC Ontario and Nunavut regions, and represent potential population threats that should continue to be monitored.

Cerebrospinal Nematodiasis in 20 Camelids

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.