Difference between revisions of "Respiratory Viral Infections"

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#REDIRECT[[:Category:Respiratory Viral Infections]]
|backcolour = D1EEEE
 
|linkpage =Cardiorespiratory System - Pathology
 
|linktext =Cardiorespiratory System
 
|maplink = Cardiorespiratory System (Content Map) - Pathology
 
|pagetype =Pathology
 
|sublink1=Respiratory System Inflammation - Pathology
 
|subtext1=RESPIRATORY SYSTEM INFLAMMATION
 
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<br>
 
==In general==
 
 
 
*Some viruses are thought to induce modifications of the pulmonary defences by:
 
**Damaging the upper respiratory tract, thereby facilitating bacterial attachment and colonisation, with reduced [[Respiratory System General Introduction - Pathology#Mucociliary escalator|mucociliary clearance]]
 
**Decreasing surfactant levels by destroying Type 2 pneu[[Monocytes|monocytes]]
 
**Impairing the phagocytic ability of alveolar macrophages
 
 
 
 
 
==In Dogs==
 
[[Canine Distemper Virus]]
 
 
 
[[Canine Parainfluenza - 2]]
 
 
 
[[Infectious Canine Tracheitis|Infectious canine tracheitis]]
 
 
 
[[Canine Adenovirus 1]]
 
 
 
[[Canine Adenovirus 2]]
 
 
 
[[Canine Herpesvirus 1]]
 
 
 
[[Canine Respiratory Coronavirus]]
 
 
 
==In Cats==
 
 
 
===[[Feline Herpesvirus 1|Feline viral rhinotracheitis]]===
 
 
 
===[[Feline Calicivirus]]===
 
 
 
==In Horses==
 
[[Image:Equine respiratory viruses concept map.jpg|right|thumb|100px|<small><center>Equine respiratory viruses Concept Map (Courtesy of B. Stanikova)</center></small>]]
 
 
 
===[[Equine rhinovirus]]===
 
 
 
===[[Equine Influenza|Equine influenza]]===
 
 
 
===[[Equine Rhinopneumonitis]] ===
 
 
 
 
 
===[[Equine Viral Arteritis]]===
 
 
 
 
 
===[[Equine Adenovirus]]===
 
 
 
 
 
===[[African Horse Sickness]]===
 
 
 
===[[Hendra Virus]]===
 
 
 
==In Cattle==
 
 
 
===[[Infectious Bovine Rhinotracheitis|Infectious bovine rhinotracheitis (IBR)]]===
 
 
 
 
 
===Parainfluenza- 3===
 
 
 
*Causative agent: [[Paramyxoviridae#Bovine Parainfluenza - 3 (PI-3)|parainfluenza- 3 virus]] (PI3)
 
*On its own causes [[Nasal Cavity Inflammatory - Pathology#Infectious causes of rhinitis|rhinitis]]
 
*Often part of multi-aetiology disease complex (e.g. [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of calves|Enzootic pneumonia of calves]]), often followed by [[:Category:Pasteurella and Mannheimia species|''Pasteurella sp.'']] obscuring viral origin
 
*Replicates in airway epithelial cells and results in an initial [[Bronchi and Bronchioles Inflammatory - Pathology#Infectious causes of bronchitis or bronchiolitis|bronchitis -> bronchiolitis]] -> extension into [[Lungs Inflammatory - Pathology#Infectious causes of pneumonia|alveoli]], causing [[Lungs Inflammatory - Pathology#Bronchointerstitial pneumonia|bronchointerstitial pneumonia]]
 
*Early stages may show [[Degenerations and Infiltrations - Pathology#Cellular Inclusions|intracytoplasmic inclusions]]
 
*The resulting exudate is predominantly neutrophilic
 
*Positive confirmation lies in a Fluorescent Antibody Test (FAT) to the specific virus on frozen sections of tissue
 
 
 
 
 
===[[Bovine adenovirus]]===
 
 
 
===Respiratory syncytial virus===
 
 
 
*Causative agent [[Paramyxoviridae|Respiratory syncytial virus (RSV)]], synonym: bovine RSV (BRSV)
 
*Outbreaks of RSV associated disease usually occur associated with winter housing
 
*Gross pathology in severe cases
 
**Cranioventral [[Lungs Ventilation - Pathology#Atelectasis (Collapse)|atelectasis]] and consolidation
 
**[[Lungs Ventilation - Pathology#Emphysema|Interstitial emphysema]]
 
***More prominent in the caudal lung lobes
 
***Results from bronchoconstriction which results in airway obstruction - this constriction is thought to arise from [[Mast Cells|mast cell]] degranulation and histamine release
 
*Histologically
 
**[[Bronchi and Bronchioles Inflammatory - Pathology#Acute bronchitis/bronchiolitis|Acute bronchiolitis]], characteristic of the bronchiolar response is the formation of syncytial giant cells  (formed by proliferating bronchiolar epithelial cells which may contain [[Degenerations and Infiltrations - Pathology#Cellular Inclusions|intracytoplasmic inclusion bodies]]), alveolar epithelium sometimes affected
 
**Obstruction of bronchioles by exudate - these may later become obliterated by the fibrous tissue of organisation
 
*May contribute to [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of calves|Enzootic pneumonia of calves]]
 
 
 
===[[Bovine rhinovirus]]===
 
 
 
==In Sheep==
 
 
 
===Maedi Visna===
 
 
 
*Caused by a [[Retroviridae|retrovirus]]
 
*The respiratory from of the disease caused by maedi-visna virus (Maedi) is also called '''lymphoid interstitial pneumonia'''
 
*Transmitted by close contact and via milk
 
*The pulmonary lesions develop very slowly hence this disease is uncommon in sheep < 2 years old
 
*Increased respiratory rate upon exertion, loss of weight
 
*Remains in [[Monocytes]] and macrophages
 
*Gross findings
 
**Severe [[Lungs Inflammatory - Pathology#Interstitial pneumonia|interstitial pneumonia]]
 
**Lungs fail to collapse properly on opening the chest and can weigh more than twice the normal weight
 
**Impressions of the ribs remain on the visceral pleura
 
**Lungs are a mottled grey/ tan colour - the lesions can vary from irregular grey speckling to homogeneous grey consolidation
 
**Rubbery in consistence
 
**Diaphragmatic lobes most affected
 
**Associated bronchial and mediastinal lymph nodes are often enlarged
 
*Histologically
 
**Major features are extensive lymphoid proliferation around perivascular, peribronchial and peribronchiolar sheaths associated with pulmonary lymphatics
 
**Many of these areas contain germinal centres and smooth muscle hyperplasia (in walls of terminal bronchioles and alveoli)
 
 
 
 
 
===Parainfluenza -3===
 
 
 
*As in [[Respiratory Viral Infections - Pathology#Parainfluenza- 3|cattle]]
 
 
 
 
 
===Pulmonary adenomatosis===
 
 
 
*See [[Lungs Hyperplastic and Neoplastic - Pathology#Sheep pulmonary adenomatosis (SPA/ Jaagsiekte)|neoplasia]]
 
 
 
 
 
==In Goats==
 
 
 
===Caprine Arthritis-Encephalitis (CAE)===
 
 
 
*Caused by [[Retroviridae|retrovirus (lentivirus)]] similar to [[Respiratory Viral Infections - Pathology#Maedi Visna|Maedi Visna]] in sheep described above
 
*Two forms:
 
**Non-suppurative leukoencephalomyelitis in young goats and kids
 
**Chronic, non-suppurative arthritis-synovitis in adult goats
 
*Also causes [[Lungs Inflammatory - Pathology#Interstitial pneumonia|interstitial pneumonia]] which tends to be obscured by other clinical signs
 
*Gross pathology:
 
**Mainly caudal lobes
 
**Lungs are firm, grey-pink with grey-white focal lesions on cut surface
 
*Micro pathology:
 
**Thickened alveolar wall
 
**Lymphocyte infiltration and type II pneumocyte hyperplasia
 
*Can be confused with or coexisting with [[Lungs Inflammatory - Pathology#Verminous pneumonia|Parasitic pneumonia]]
 
 
 
 
 
==In Pigs==
 
 
 
===Inclusion body rhinitis===
 
[[Image:Inclusion body rhinitis.jpg|right|thumb|100px|<small><center>Inclusion body rhinitis (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
 
 
 
*[[Herpesviridae|'''Herpesviridae, porcine cytomegalovirus''']]
 
*Disease of suckling piglets 1-5 wks of age
 
*Clinical signs: those associated with acute/subacute [[Nasal Cavity Inflammatory - Pathology#Infectious causes of rhinitis|rhinitis]] (ie: serous nasal discharge, progressing to catarrhal or purulent discharge with time and secondary bacterial infections; sneezing; pyrexia), fever in young piglets (3-8wks old)
 
*May progress to [[Paranasal Sinuses Inflammatory - Pathology#Sinusitis|sinusitis]], otitis media or [[Lungs Inflammatory - Pathology#Infectious causes of pneumonia|pneumonia]]
 
*Morbitity high, mortality low
 
*Gross pathology - catarrhal discharge becoming purulent (secondary infection)
 
*Histology:
 
**Large basophilic [[Degenerations and Infiltrations - Pathology#Cellular Inclusions|intranuclear inclusion bodies]] in the surface and subepithelium of nasal and sinus glandular epithelium with lymphocytic infiltration of the mucosa
 
**Bursting of nucleus with cell necrosis and sloughing of necrotic epithelium
 
*Can develop viraemic stage, with inclusions and focal necrotising lesions in other organs eg: renal tubular epithelium
 
**Usually younger piglets, can die during this phase
 
*Usually resolves if uncomplicated but rhinitis may persist if secondary infection is present
 
*May persist in pulmonary macrophages
 
 
 
 
 
===[[Swine Influenza|Swine influenza]]===
 
 
 
===Porcine reproductive and respiratory syndrome===
 
 
 
*The syndrome is caused by a small enveloped RNA virus which belongs to the new [[Arteriviridae|Arteriviridae]] group
 
*Replicates in and destroys macrophages and endothelial cells causing vasculitis -> viraemia -> virus shedding (nasal secretions, faeces)
 
*Clinical signs: respiratory and reproductive failure, weaned pigs, tachypnoea, eyelid oedema, conjunctivitis
 
*Moderate to severe interstitial [[Lungs Inflammatory - Pathology#Infectious causes of pneumonia|pneumonia]] in the cranial lobe
 
*Superimposed bacterial infections are common
 
*Infectious disease in swine that emerged 10 years ago
 
*Today, PRRS is endemic in many if not all the pig-producing countries
 
 
 
 
 
===Postweaning multisystemic wasting syndrome (PMWS)===
 
 
 
*Caused by a [[Circoviridae|porcine circovirus]] alone or in combination with [[Parvoviridae|porcine parvovirus]]
 
*May cause mild [[Lungs Inflammatory - Pathology#Interstitial pneumonia|interstitial pneumonia]], failure of lungs to collpse on opening the thoracic cavity
 
*Microscopically: thickening of alveolar wall due to type 2 pneumocyte hyperplasia
 
 
 
 
 
===[[Porcine respiratory coronavirus]]===
 

Latest revision as of 11:22, 20 July 2010