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| − | {{unfinished}}
| + | #REDIRECT[[:Category:Paramyxoviridae]] |
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| − | {{toplink
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| − | |linkpage =Viruses
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| − | |linktext =VIRUSES
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| − | |pagetype=Bugs
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| − | }}
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| − | <br>
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| − | =Introduction=
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| − | =Morphology=
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| − | *Single-stranded negative-sense unsegmented RNA virus
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| − | *Reassortment and antigenic shift cannot occur
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| − | *Spike proteins include '''HN''' (Haemagglutinin and Neuraminidase) and '''F''' (Fusion glycoprotein), which allows the virus to fuse directly to the plasma membrane and release its RNA
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| − | **F also causes syncitium to form, which aids diagnosis
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| − | =Virulence=
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| − | *Paramyxoviruses replicate in the epithelium of the upper respiratory tract as well as occasionally in the gut
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| − | =Types and Subtypes=
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| − | =Paramyxoviridae by Species=
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| − | ===Overview===
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| − | *Systemic infections - controlled by '''live monotypic vaccination'''
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| − | *Respiratory infections - ''not'' controled by '''live monotypic vaccinations'''
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| − | *[http://www.pitt.edu/~super1/lecture/lec3401/index.htm On line Paramyxoviridae lecture by P. Russell]
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| − | ===Classification===
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| − | *'''Paramyxovirinae'''
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| − | **[[Paramyxoviridae#Bovine Parainfluenza - 3 (PI-3)| Bovine Parainfluenza 3]]
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| − | **[[Paramyxoviridae#Canine Parainfluenza - 2|Canine Parainfluenza 2]]
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| − | **[[Paramyxoviridae#Murine Parainfluenza - 1 (Sendai virus)|Murine Parainfluenza 1 (Sendai virus)]]
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| − | **[[Paramyxoviridae#Newcastle Disease Virus (NDV)|Newcastle Disease (NDV)]] - avian paramyxovirus serotype 1
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| − | **Avian Paramyxoviruses serotypes 2-9
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| − | **[[Paramyxoviridae#Reptilian Paramyxoviruses|Reptilian Paramyxoviruses]]
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| − | **Mumps
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| − | *'''Morbilliviruses'''
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| − | **[[Paramyxoviridae#Canine Distemper Virus (CDV)|Canine Distemper (CDV)]]
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| − | **Rinderpest
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| − | **Pest de petit ruminant (PPR)
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| − | **Measels
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| − | **Seal virus - phocine distemper
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| − | **Dolphin Morbillivirus
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| − | **[[Paramyxoviridae#Hendra Virus|Hendra virus]]
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| − | **[[Paramyxoviridae#Nipah Virus|Nipah virus]]
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| − | *'''Pneumovirinae'''
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| − | **[[Paramyxoviridae#Bovine Respiratory Syncytial Virus (BRSV)|Bovine Respiratory Syncytial Virus (BRSV)]]
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| − | **Turkey Rhinotracheitis Virus
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| − | ===Virus properties===
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| − | ====Structure====
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| − | *Negative sense '''RNA''', unsegmented, single stranded
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| − | **-> '''Reasortment''' and '''antigenic shift''' cannot occur
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| − | *'''HN spike''' contains:
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| − | **'''Haemagglutinin (H)'''- attachment protein
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| − | **'''Neuraminidase (N)'''
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| − | *'''Fusion''' glycoprotein (F) spike
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| − | **-> Viral lipid bilayer can fuse directly with host plasma membrane
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| − | ***-> RNA released into cytoplasm
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| − | **->Syncytium (multinucleated giant cells) in lesions and cell culture
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| − | **Host antibody response to this protein is most important
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| − | ***Best induced by '''live attenuated vaccines'''
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| − | ====Growth ''in vitro''====
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| − | *Allantoic cavity of 10-day-old eggs
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| − | *Followed by '''haemagglutination'''
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| − | ====''In vivo''====
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| − | *Cell tropism for upper respiratory tract epithelium
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| − | **All replicate in these cells
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| − | *Some replicate in the gut
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| − | *Most virulent replicate in lymphoid cells and neurons ([[Paramyxoviridae#Canine Distemper Virus (CDV)|Distemper]], [[Paramyxoviridae#Newcastle Disease Virus (NDV)|NDV]])
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| − | *Links to the readiness to cleave Fo and Ho precursors in different cells
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| − | ====Antigenic differentiation====
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| − | *Major conserved immunodominant virus-specific antigens on [[Paramyxoviridae#Structure|F and HN]]
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| − | **-> Vaccines protect against all isolates of the same virus
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| − | *Minor morbillivirus-specific epitopes on [[Paramyxoviridae#Structure|F]]
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| − | **Some crossprotectin between [[Paramyxoviridae#Canine Distemper Virus (CDV)|canine distemper]], measels and rinderpest
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| − | *Minor variable epitopes of [[Paramyxoviridae#Structure|F, HN and '''NP''']]
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| − | **Allows antigenic '''fingerprinting'''
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| − | ===Newcastle Disease Virus (NDV)===
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| − | *'''Hosts'''
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| − | **Gallinaceous birds, pigeons, parrots, finches
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| − | **Subclinical carriers: ducks, ostriches
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| − | **Causes conjunctivitis in humans
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| − | *'''Virulence'''
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| − | **Disease ranges from subclinical [[Respiratory Viral Infections - Pathology|respiratory tract infections]] -> torticollis -> haemorrhages and death
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| − | *'''Epidemiology'''
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| − | **Air-born
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| − | **Direct contact of poultry
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| − | *'''Diagnosis'''
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| − | **Samples of trachea and gut of 20 birds are tested in eggs
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| − | **'''HI''' using anti-NDV serum (to differentiate '''HA''' caused by [[Orthomyxoviridae|avian influenza]]
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| − | **Animal test: virulence of isolate tested by the speed it kills chicks
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| − | **Sequencing the cleavage site of [[Paramyxoviridae#Structure|H]] gene
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| − | ***The more basic amino acids the more virulent the virus
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| − | ***Now replacing the animal test
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| − | *'''Control'''
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| − | **Isolation of stock
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| − | **Vaccination of chickens and racing pigeons
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| − | **Surveillance of imported exotic birds
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| − | **Notifiable disease
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| − | **Infected premises to be culle and firebreak cull if spread
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| − | ===Reptilian Paramyxoviruses===
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| − | *Infect central nervous system and lungs
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| − | *Kill particularly snakes
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| − | *Healthy reptiles may be carriers
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| − | *Testing by serology - '''HI test'''
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| − | *Aim to keep virus free collection and prevent spread back into the wild
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| − | ===Murine Parainfluenza - 1 (Sendai virus)===
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| − | *Endemic in many mouse colonies
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| − | *Most mice show no symptoms due to maternal antibodies
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| − | *But minor respiratory lesions may invalidate carcinogenic or toxicological studies
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| − | *Immunological studies also confused due to virus activating [[General Pathology - Antigen Recognition, Processing and Presentation#NK Receptors|NK cells]] via high circulating [[Innate Immune System - WikiBlood#Interferons|IF]] 3-4 days post-infection
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| − | *Control achieved by:
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| − | **Purchasing specific pathogen free (SPF) mice
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| − | **Kill whole colony in an outbreak -> disinfection -> formalin fumigation
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| − | ===Canine Parainfluenza - 2===
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| − | *or Parainfluenza - 5
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| − | *Infects dogs
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| − | *May cause mild upper respiratory infection, [[Nasal Cavity Inflammatory - Pathology#Infectious causes of rhinitis|rhinitis]]
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| − | **Virus shed for a short time only
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| − | *Also part of kennel cough ([[Respiratory Viral Infections - Pathology#Infectious canine tracheitis|Infectious canine tracheitis]]), together with [[Bordetella bronchiseptica and Bordetella avium|''Bordetella bronchiseptica'']]
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| − | *Control:
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| − | **'''Live attenuated vaccine''' may be incorporated in multivalent vaccines
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| − | ***Immunity is short-lived
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| − | ***Only reduces severity of clinical signs
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| − | ===Bovine Parainfluenza - 3 (PI-3)===
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| − | *Virulence varies with isolates
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| − | *Cessation of [[Respiratory System General Introduction - Pathology#Mucociliary escalator|ciliary clearance]] and epithelial necrosis predisposes to secondary bacterial infections -> cough
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| − | *May cause [[Respiratory Viral Infections - Pathology#Parainfluenza- 3|rhinitis]] of cattle
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| − | *With other agents causes [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of calves|calf pneumonia ]]
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| − | **Together with managemental factors (overcrowding, poor ventilation, high humidity, deprivation of colostrum and stress caused by transport or mixing of stock)
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| − | *'''Diagnosis'''
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| − | **Diseased lung tissue from dead animals or centrifuged cells from lung lavage
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| − | **Virus is too fragile for cell culture isolation (often inactivated intransport)
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| − | **Antigen detection by ''' immunocytochemistry''' for intracytoplasmic viral inclusions containing labelled viral protein
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| − | **Serology: 4-fold rise in ELISA antibody in paired serum samples from several animals
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| − | *'''Control'''
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| − | **Improve managemental factors
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| − | **All-in, all-out systems
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| − | **Some vaccination
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| − | ***Temperature sensitive mutant that replicates at 34<sup>o</sup>C but not at 37<sup>o</sup>C
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| − | ***Re-infection is common
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| − | ===Bovine Respiratory Syncytial Virus (BRSV)===
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| − | *'''Pathogenesis''':
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| − | **More serious than [[Paramyxoviridae#Parainfluenza -3 (PI-3)|PI-3]]
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| − | **Causes [Respiratory Viral Infections - Pathology#Respiratory syncytial virus|respiratory infection]]
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| − | **Replicates in nasal epithelium -> throughout upper respiratory tract -> bronchial tree
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| − | **Syncytia form -> shed into bronchioles
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| − | **Complications include [[Lungs Ventilation - Pathology#Emphysema|emphysema]] and [[Lungs Circulatory - Pathology#Pulmonary oedema|oedema]], drop in milk yield in adult cattle
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| − | *'''Epidemiology''':
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| − | **Subclinical reinfections are important in spreading disease
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| − | **More than 70% of cattle in the UK have antibodies to BRSV
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| − | *'''Diagnosis''' is same as for [[Paramyxoviridae#Parainfluenza -3 (PI-3)|PI-3]]
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| − | *'''Control'''
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| − | **Improve husbansry as in [[Paramyxoviridae#Parainfluenza -3 (PI-3)|PI-3]]
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| − | **Vaccines are available but not effective as need to stimulate [[Lymphocytes - WikiBlood#Cytotoxic CD8+|cytotoxic T-cells]]
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| − | *<small>'''Reference''': Bryson, 1999, Update on calf pneumonia, CPD Veterinary Medicine, 1,3, 90-95</small>
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| − | ===Canine Distemper Virus (CDV)===
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| − | *Hosts: dogs, ferrets, seals, lions, mink
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| − | *Has been a major pathogen of dogs prior to vaccination
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| − | *Variable mortality depending on virulence
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| − | *May occur subclinically
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| − | *Involvement of central nervous system generally results in death
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| − | *'''Pathogenesis''':
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| − | **Aerosol infection
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| − | **Infects alveolar [[Macrophages - WikiBlood|macrophages]] or [[Oropharynx - Pathology|oropharynx]]
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| − | **Multiplies in the bronchial and other lymph nodes, infects monocytes and dendritic cells
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| − | **Viraemia
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| − | **Spreads via monocytes to a variety of epithelium depending upon the strain of virus
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| − | **[[Respiratory Viral Infections - Pathology#Canine distemper|Respiratory]] and alimentary tracts, skin and later (1-5 wk. post infection) to the brain
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| − | *'''Clinical signs''':
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| − | **Mucopurulent oculonasal discharge
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| − | **Keratitis
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| − | **[[Lungs Inflammatory - Pathology#Interstitial pneumonia|Interstitial pneumonia]]
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| − | **Severe clinical pneumonia follows secondary infection with [[Bordetella bronchiseptica and Bordetella avium|''Bordetella bronchiseptica'']]
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| − | **Smelly sometimes bloody diarrhoea
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| − | **Eruptions on the skin including hyperkeratosis of the nose and pads (hardpad)
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| − | **[[PNS Repsonses to Injury - Pathology#Segmental Demyelination|Demyelination]] (especially in cerebellum) -> incoordination or muscle tremors -> paralysis and coma or convulsions -> death
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| − | **Encephalitis
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| − | **Secondary pyogenic infections associated with immunosuppression and damage to epithelia
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| − | **Recovered animals may have persistent or spasmodic chorea
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| − | **The severity of the disease may vary; if enough neutralising antibody develops in the early stages, the virus maybe kept restricted largely to the lymph nodes.
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| − | *'''Diagnosis''':
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| − | **May present as series of infections
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| − | **'''Immunocytochemistry''' of inclusion bodies
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| − | ***Intracytoplasmic inclusions may be found in most affected tissues
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| − | ***Inclusions persist longest in the brain (may be intranuclear) and the alveolar macrophages
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| − | ***Sections of fixed bronchial tissue, lung, macrophages, bladder may be used or nasal or conjunctival epithelium from live animals
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| − | **Giant cells may be seen in the alveoli
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| − | *'''Control''':
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| − | **Live attenuated virus vaccines given at 10 and 12 weeks of age
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| − | ***Some now given at 7 and 10 weeks to allow socialisation
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| − | **Homeopathic vaccines do not work
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| − | **Live attenuated vaccines may kill some wildlife therefore '''Iscom vaccine''' is used in seal sanctuaries
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| − | *Can contribute to [[Respiratory Viral Infections - Pathology#In Dogs|Infectious canine tracheitis]]
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| − | *May be involved in [[Pancreas Inflammatory - Pathology#Chronic interstitial pancreatitis|chronic interstitial pancreatitis]]
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| − | *May cause [[Bones Developmental - Pathology#Retention of elongated primary trabeculae|growth retardation lattice]]
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| − | *May also trigger latent [[Tissue cyst-forming coccidia|Toxoplasmosis]] due to suppressing effect on lymphoid tissue
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| − | ===Hendra Virus===
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| − | *Equine Paramyxovirus
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| − | *Causes [[Respiratory Viral Infections - Pathology#Hendra virus|respiratory infections]] with respiratory distress and paralysis
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| − | *Potentially zoonotic (beware palpating inside the throat for obstruction)
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| − | ===Nipah Virus===
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| − | *Infects pigs and humans
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| − | *Humans exposed to pig blood are at risk
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| − | <big><center>[[Viruses|'''BACK TO VIRUSES''']]</center></big>
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