CDV, HeV, NDV Flashcards
1
Q
What is the structure of Paramyxoviridae viruses?
A
- (-)ssRNA
- 15kb
- enveloped (gp H & F)
2
Q
What is the stability of Paramyxoviridae viruses?
A
- Sensitive to disinfectants
- relatively unstable outside the host
3
Q
What are some of the Paramyxoviridae viruses?
A
- Canine Distemper Virus (CDV)
- Newcastle disease virus (NDV)
- Hendra Virus (HeV)
- Measles
4
Q
What is Canine Distemper Virus (CDV)?
A
- Highly contagious, systemic viral disease of dogs
- Seen world wide
- Large # of species susceptible:
- Canidae
- Mustelidae (ferret, mink, otter, badger)
- Procyonidae (raccoon)
- Viveridae (palm civet)
- Ailuridae (red panda)
- Ursidae
- Felidae (large cats)
- Domestic dogs are the reservoir species
5
Q
How is CDV transmitted?
A
- Primary route: aerosol droplets from infected animals
- Virus shedding may occur for several months
6
Q
What is Phase 1 of CDV infection?
A
- Initial virus replication occurs in the lymphatic tissues of the respiratory tract
- macrophages and bronchial ln
7
Q
What is Phase 2 of CDV infection?
A
- Within 1 week:
- a cell-associated viremia results in virus replication spreading to all lymphatic tissues
- Spleen, bone marrow, thymus, and lymphocytes
- a cell-associated viremia results in virus replication spreading to all lymphatic tissues
8
Q
How does CDV cause immune suppression?
A
- Depletion of vascular CD3+ T cells and CD21+ B cells within 3 days after infection
- Monocyte apoptosis by 6 days post infection
- Necrosis and depletion of the cortical region of the lymph nodes occurs
- Leukopenia!
9
Q
How does the body fight against CDV?
A
- Both cell-mediated and humoral immune response necessary for protection
- Degree of viremia and extent of viral spread is moderated by the level of specific humoral immunity (neutralizing Abs) during the viremic period
- If neutralizing Abs are not present, virus persists in the lymphatic system and spreads
10
Q
What is Phase 3 of CDV infection?
A
- “mucosal phase”
- Viral infection spreads to respiratory, gastrointestinal, and urogenital epithelium, skin, endocrine tissues, CNS and optic nerves
11
Q
What is a pantropic virus?
A
virus with affinity for many tissues
12
Q
What are the clinical signs of CDV?
A
- Biphasic fever
- Neurological signs
13
Q
What is biphasic fever associated with CDV?
A
- Transient fever ⇢ subclinical
- May have leukopenia
- may have inappetence
- 3-6 dpi then subsides
- Second fever ⇢ Clinical signs occur
- Serous nasal discharge, rhinitis, mucopurulent ocular discharge, conjunctivitis, cough, dyspnea, diarrhea, vomiting, lethargy, dermatitis, and inappetence
- Typically complicated by secondary bacterial infections
- Thoracic radiographs may reveal interstitial pneumonia
14
Q
What neurological signs are associated with CDV?
A
- Longer courses of illness - onset may be delayed due to chronic progressive demyelination w/in CNS
-
Encephalomyelitis
- may occur with other signs, follow systemic disease, or alone
- Circling, blindness, head tilt, nystagmus, paresis to paralysis, focal to generalized seizures
- Localized involuntary muscle twitching, convulsion characterized by salivation and chewing movements of the jaw
15
Q
What is the pathogenesis of Acute CNS infections with CDV?
A
- CDV targets Neurons and Glial cells ⇢ Neuronal degeneration and inflammation (grey matter disease)
16
Q
What is the pathogenesis in Subacute CNS infections with CDV?
A
- CDV targets oligodendrocytes ⇢ down-regulation of myelin production (white matter disease)
17
Q
Which is more common grey or white matter disease with CDV infections?
A
- typically mixed
- pure grey matter disease is rare
18
Q
What is “Old dog encephalitis”
A
- Chronic distemper encephalitis
- Ataxia, head pressing, continual pacing, uncoordinated hypermetria
- May be seen in fully vaccinated adult dogs w/out a history of acute CDV infections
- CDV antigen detected in brain but not infectious virus
- Neurological signs due to inflammatory reaction associated with persistent CDV infection in CNS
- Poorly understood, mechanism unknown
19
Q
What are issues are seen post CDV infection?
A
- Cutaneous hyperkeratosis
- Enamel hypoplasia
20
Q
What is cutaneous hyperkeratosis associated with post CDV infection?
A
- On the footpads and epithelium of nasal planum
- Keratinocyte proliferation
- Callusing of the nose and footpads
- Hard pad disease
21
Q
What is enamel hypoplasia associated with post CDV infection?
A
- infected puppies whose permanent teeth have not erupted
- CDV targets the ameloblastic epithelium (makes tooth enamel)
- Enamel defects (focal depressions, pitting on permanent teeth
22
Q
What gross pathologic lesions are seen with CDV?
A
- Thymic atrophy (young puppies)
- Bronchopneumonia, enteritis, pustular dermatitis
- Hyperkeratosis f nose and footpads
23
Q
What Microscopic lesions are seen with CDV?
A
- Necrosis of lymphatic tissues
- Interstitial pneumonia
- Inclusion bodies in respiratory, urogenital and gastrointestinal epithelium, WBC and RBC
- Neuronal degeneration, gliosis, noninflammatory demyelination, perivascular cuffing, nonsuppurative leptomeningitis, inclusion bodies in glial cells and neurons
24
Q
How is CDV diagnosed?
A
- Should be considered for any febrile condition in dogs with multisystemic manifestations
- Unvaccinated dogs between 3-6 months of age at greatest risk
- IFA, RT-PCR, Serum, IHC
- Conjunctival, tracheal, vaginal or other epithelial smears
- Buffy coat, urine sediment, bone marrow aspirate, feces VI generally not successful
- Antibody detection (CSF, blood):
- Higher titer in CSF vs blood - typical of natural infection
- Elevated IgM levels
25
Q
What is the treatment for CDV?
A
- Nonspecific, supportive treatment
- prevent secondary bacterial infections
- Fluid therapy
- Managing neurologic manifestations (anticonvulsants)
- With aggressive car, dogs may fully recover from multisystemic disease or may have long term neurologic signs
26
Q
What is the prognosis for CDV?
A
- Poor prognosis for acute, progressive, or severe neurologic disease
27
Q
What is the CDV vaccination?
A
- Core Vaccine - AAHA
-
Modified live virus vaccine
- pups vaxed at 6wks, then every 2-4 wks until 16 wks of age
- Booster at 1 year then every 3
- NOT be used if pregnant or early-lactation
- can produce illness in immunosuppressed dogs
- Recombinant canarypox vector vaccine:
- Licensed for use in dogs and ferrets
- AAZV recommends etra-label use in zoo species
27
Q
What is the CDV vaccination?
A
- Core Vaccine - AAHA
-
Modified live virus vaccine
- pups vaxed at 6wks, then every 2-4 wks until 16 wks of age
- Booster at 1 year then every 3
- NOT be used if pregnant or early-lactation
- can produce illness in immunosuppressed dogs
- Recombinant canarypox vector vaccine:
- Licensed for use in dogs and ferrets
- AAZV recommends etra-label use in zoo species
28
Q
What is Newcastle Disease Virus?
A
- Infectious disease of poultry and wild birds
- >250 species susceptible
- Worldwide distribution
- Zoonotic - self-limiting conjunctivitis, mild flu-like symptoms
29
Q
What are the different strains of NDV?
A
- Virulent strains - “exotic Newcastle Disease” in US
- Reportable with trade restrictions
- Mortality rate: 70-100%
- Low virulence strains - mild clinical disease - Common in US
30
Q
How is NDV transmitted?
A
- Direct or indirect contact with secretions and excretions from infected birds
- inhalation +/- ingestion
31
Q
What are the virulent NDV strains?
A
- Reportable
- Viscerotrophic velogenic ND (VVND)
- Neurotrophic velogenic ND (NVND)
- Mesogenic
32
Q
What are the low virulence strains of NDV?
A
- Used as live vaccines
- Not reportable
- Lentogenic
- Asymptomatic lentogenic
33
Q
What are the clinical signs of NDV?
A
- Torticollis
- Eyelid edema
- Weakness
- Inability to rise
- Eyelid hemorrhage
- Foamy discharge
34
Q
What are the gross lesions associated with NDV?
A
- Splenic necrosis
- Pancreas necrosis
- Tracheal mucosal hemorrhage
- Intestinal necrosis and hemorrhage
35
Q
How is NDV diagnosed?
A
- Oropharyngeal or cloacal swabs
- RT-PCR or HI, Sequencing
36
Q
Are there vaccines for NDV?
A
- Live low virulence strains
- mass admin in drinking water
- individual nares or conjunctival sacs
- inactivated and vectored vaccines
37
Q
What viruses are part of the Genus Heniparvirus?
(family Paramyxoviridae)
A
- Hendra virus (horses & humans)
- Nipah virus (swine & humans)
38
Q
What is Hendra virus?
A
- 1994 Hendra, Australia - outbreak of acute, febrile respiratory/neurologic disease with high lethality in horses (89%) and handlers (57%)
- Flying foxes are reservoir hosts
- Continued sporadic cases in E. Australia
- Transmission generally NOT via aerosols
- Body fluids from infected flying foxes - urine, placental fluids, other bodily fluids, tissues
39
Q
What is the pathogenesis of Hendra Virus?
A
- Nasopharyngeal exposure ⇢ Replication in macrophages and bronchial ln ⇢ Disseminated in blood (primary consequences in lungs
- Believed to be based on widespread vasculitis due to tropism of virus for vascular tissues
*
- Believed to be based on widespread vasculitis due to tropism of virus for vascular tissues
40
Q
What are the clinical signs of Hendra virus?
A
-
Acute interstitial pneumonia
- Frothy nasal discharge, respiratory distress, inappetence
- Vasculitis, hemorrhage, and edema
- Neurologic disease
- Neuronal necrosis and focal gliosis
- Ataxia, weakness, head tilt, recumbency, restlessness
41
Q
How is Hendra Virus diagnosed?
A
- Suspect : acute onset of fever ⇢ rapid progression to death
- Samples; Blood, nasal, oral, and/or rectal swabs
- REPORTABLE - BSL-4 laboratory diagnosis
