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<big><center>[[Viruses|'''BACK TO VIRUSES''']]</center></big>
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#REDIRECT[[:Category:Paramyxoviridae]]
 
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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 [[Viral infections|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 [[General Pathology - Innate Immunity#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#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 ([[Viral infections#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#Mucociliary escalator|ciliary clearance]] and epithelial necrosis predisposes to secondary bacterial infections -> cough
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*May cause [[Viral infections#Parainfluenza- 3|rhinitis]] of cattle
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*With other agents causes [[Bacterial infections#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 [Viral infections#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#Emphysema|emphysema]] and [[Lungs - circulatory#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 [[General Pathology - T-cell Activation and Function#Cytotoxic T-Cells|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 - Anatomy & Physiology|Macrophages]] or [[Oral Cavity - Oropharynx|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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**[[Viral infections#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#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#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 [[Viral infections#In Dogs|Infectious canine tracheitis]]
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*May be involved in [[Pancreas - inflammatory#Chronic interstitial pancreatitis|chronic interstitial pancreatitis]]
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*May cause [[Bones - developmental#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 [[Viral infections#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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