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Infectious Diseases Exam 3
Terms in this set (22)
Bovine respiratory disease complex - another common name for this? Where in the body? What clinical signs/what lesions? Factors predisposing cattle to this?
Lower respiratory tract; causes bronchopneumonia (fibrinosuppurative; depression, slow moving, anorexic, lack of rumen fill, maybe fever, increased respiratory rate, dyspnea, abnormal lung sounds, cough, ocular & nasal discharge) but can also see sepsis, joint infections, mastitis, neuro signs, mucosal erosions, abortions
Host (immunity, young are more prone, weaning status, source), environment (transportation, stress, weather, marketing, commingling), & pathogen factors
Causative agents of bovine respiratory disease complex
Mannheim haemolytica, Pasteurella multocida, Histophilus someone, Mycoplasma bovis, (these 4 bacteria are common commensals of upper respiratory tract in cattle, but abnormal when found in lower respiratory tract)
Bovine Herpesvirus 1 (Infectious Bovine Rhinotracheitis), Bovine respiratory syncytial virus, BVD, Parainfluenza-3, & maybe Bovine respiratory coronavirus
Species/ages often affected with bovine respiratory disease complex
Dairy - enzootic pneumonia in calves, rare in adults
Beef - Shipping fever (feedlot animals) or pre-weaned calves on grass, rare in adults
Where is mycoplasma bovis found?
Can survive in environment, in unpasteurized milk, & in respiratory droplets
Prevention of bovine respiratory disease complex?
General good husbandry (nutrition, clean water, comfy place to rest), reduce stress, limit commingling, improve immunity, sanitation, biosecurity
Ddx for bovine respiratory diseases
Atypical Interstitial Pneumonia, heat stress, Calf Diphtheria (necrotic laryngitis), tracheal edema syndrome (honkers), tuberculosis
What is a tool we can use to evaluate cattle & find sick animals? Drawback?
Clinical illness score (Example: CIS 1-4 where 1 is clinically normal)
Why is it so hard to find sick calves?
Prey animals, Bos Indicus cows like to hide being sick, case definition important but difficult to assess (temperature? What is the cutoff?), antemortem clinical signs are non specific, need to look at lots of calves
Antemortem diagnostic methods to test for bovine respiratory disease complex
Behavior monitoring (accelerometers, pedometers, real time location monitors, etc), PE in chute, rectal temperature, lung auscultation (olecranon to 11th rib), lung ultrasound if needed
Maybe a culture/sensitivity (some grow better than others) of a nasal/nasopharyngeal swab or bronchoalveolar lavage or transtracheal wash; maybe PCR; maybe virus isolation
Postmortem diagnostic methods/lesions to test for bovine respiratory disease complex
Necropsy (look for lung lesions)
Equine Encephalomyelitis viruses (WEE, EEE, VEE): what is the transmission/hosts?
Via mosquito bite (+ horse to horse for VEE)
Birds (WEE & EEE) or cotton rats (VEE) are reservoir species (maintain the virus before the mosquito comes to bite it)
Horses & humans are dead end hosts
Which equine encephalomyelitis virus is the worst? The "best?" Which are in the US currently?
EEE (worst, highest mortality) > VEE >>>> WEE
EEE & WEE in US currently (so are core vaccines)
Equine encephalomyelitis viruses - diagnostics (antemortem & postmortem)?
Antemortem: CSF tap (look for neutrophils, macrophages, & lymphocytes if EEE; look for mostly lymphocytes if WEE; BUT IT'S NOT USEFUL/PATHONEUMONIC), confirmatory serology (test for IgM via ELISA, so test early on after horse shows clinical signs)
Postmortem: *VIRUS ISOLATION/CULTURE IS THE GOLD STANDARD (but do NOT freeze the neuro tissue samples, this destroys the sample)
Equine Protozoal Myeloencephalitis - causative agent (affects what body system)? Clinical signs? Diagnosis?
Sarcocystis neurona (affects CNS);
unilateral muscle atrophy (look at rump, tongue for unilateral wrinkles, etc), ataxia
Dx: CSF analysis + PCR (false negatives uncommon), serology (Western Blot, IFA, or ELISA looking for presence of Abs to surface Ags)
Core vaccines for horses? How often should these be given?
EEE/WEE (given every 6 months starting a month before the vector season if in endemic area; otherwise give annually), WNV (same as the encephalomyelitis viruses), Tetanus (annually or upon injury), Rabies (annually)
Describe IgM vs IgG capture ELISAs for EEE/WEE/VEE/WNV
IgM - detects acute infection from 6-60 days post-infection; after 2 months infected animals will be IgM negative (vaccinated animals will NOT test +)
IgG - detects infection from ~2 weeks post infection & remains + for 1-2 years & possibly longer (vaccinated animals will test +)
Sarcocystis neurona life cycle. Definitive host? Intermediate host?
Definitive host (opossum) poops out infective sporocyst --> ingestion of opossum poop by horse --> infected gut --> parasitemia --> CNS infected (not peripheral nerves; lesions in brain & spine) --> clinical signs & severity dependent on where in CNS
IH: cat, skunk, raccoon, otters
Which equine encephalitis viruses are most common in the US?
EEE & WNV
Prognosis of EEE/WEE? WNV? EPM?
EEE/WEE - EEE has HIGH (70-90%) mortality, WEE has 3-50% mortality
WNV - likely to have relapses of neuro signs, affected horses have guarded to good prognosis for full recovery (1/3 have lifelong neuro deficits), recovered horses likely to develop lifelong immunity
EPM - 70% horses improve with treatment, 1/3 return to complete normalcy (early treatment, less severe clinical signs mean better odds of recovery)
Other species (other than horses & humans & reservoir species like birds) can get WEE? clinical signs in these animals?
TURKEYS, partridge, pheasants, emus (anorexia, sternal recumbency, head tilt, weird head position, acute paralysis, muscle tremors, ataxia, lateral recumbency with kicking & paddling)
Prevention of equine encephalitis viruses (EEE/WEE/VEE/WNV)?
Mosquito control & vaccination (1 month prior to mosquito season, or every 6 months in areas like Texas with extended mosquito season)
Seasonal predilection of EPM?
Maybe more in summer & fall (correlated with opossum density)
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