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Respiratory Parasitic Infections - Pathology (view source)

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==In Dogs==
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*Useful websites:
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**[http://www.ivis.org/advances/Parasit_Bowman/ddb_resp/chapter_frm.asp?LA=1 Cat and dog respiratory parasites (part 1)] - Nasal Mucosa and Sinuses, and Respiratory Parenchyma
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**[http://www.ivis.org/advances/Parasit_Bowman/ddb_resp2/chapter_frm.asp Cat and dog respiratory parasites (part 2)] - Trachea and Bronchi, and Pulmonary Vessels
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===[[Metastrongyloidae|'''''Filaroides osleri''''']]===
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* = ''Oslerus osleri''
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*Colonise the [[Trachea - inflammatory#Infectious causes of tracheitis|trachea of dogs]]
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*Larva and adults accumulate in submucosal nodules of up to 1cm diameter at the tracheal bifurcation.
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*Minimal inflammatory host reaction to the nematodes when they are alive - the size of the nodule is related to the number and size of the nematodes within it.
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*When the parasites die, an intense foreign body reaction develops
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*Tracheal nodules can cause coughing, usually in young dogs <18 months old.
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*Severe infestation can cause significant occlusion of the airway.
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*Uncommon, but sometimes seen in coughing greyhounds
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===[[Crustacea|''Linguatula serrata'']]===
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*Synonym: tongue worm
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*In [[Nasal cavity - inflammatory#Infectious causes of rhinitis|nasal passages]] of dogs, sometimes cats
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*May reach the [[Paranasal sinuses - inflammatory#Infectious causes of sinusitis|sinuses]]
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*Heavy infections may cause sneezing, coughing, nasal discharge
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===[[Metastrongyloidae|''Angiostrongylus vasorum'']]===
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*Adult worms live in the [[Lungs - circulatory|pulmonary arteries]] and '''right side of the heart''' dogs and foxes
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*Cause a proliferative endoarteritis
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*More severe damage is caused however by eggs lodging in arterioles and capillaries
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*In severe infection, this can result in [[Lungs - inflammatory#Infectious causes of pneumonia|pneumonia]] and [[Lungs - circulatory#Pulmonary oedema|pulmonary oedema]] as an acute syndrome
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*Circulatory impedance can result in congestive cardiac failure
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*Particularly a problem if dogs eats snails
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*Gross:
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**Patchy white appearance with haemorrhagic areas within
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*Microscopically:
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**Golden pigment within macrophages (haemosiderin)
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**Inflammation and scarring of alveolar walls -> enlargement of remaining air spaces
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*Worms secrete anticoagulant -> haemorrhage in other parts of body
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*May present as neurological cases due to the haemorrhage
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*May cause [[Lungs - circulatory#Embolism, thrombosis and infarction|pulmonary thromboembolism]]
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===[[Filarioidea|''Dirofilaria immitis'']]===
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*Establish in '''heart''' and [[Lungs - circulatory|pulmonary arteries]]
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*Larvae migrate through connective tissue
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*Immature adults move to caudal distal pulmonary arteries causing diffuse eosinophilic reaction in lung parenchyma, then migrate back to right ventricle
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*May cause [[Lungs - circulatory#Embolism, thrombosis and infarction|pulmonary thromboembolism]]
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===[[Trichinelloidea|''Capillaria aerophila'']]===
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*In [[Nasal cavity - inflammatory#Infectious causes of rhinitis|nasal passages]], [[Paranasal sinuses - inflammatory#Infectious causes of sinusitis|sinuses]], [[Trachea - inflammatory#Infectious causes of traacheitis|trachea]] and [[Bronchi and bronchioles - inflammatory#Infectious causes of bronchitis or bronchiolitis|bronchi]] of cats and dogs
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*Some dogs cough but often no symptoms
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*Mild catharral inflammation
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*In heavy infestation may cause obstruction of the lumen of airways and may develop into secondary [[Lungs - inflammatory#Bronchopneumonia|bronchopneumonia]]
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===Toxoplasmosis===
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*Caused by [[Tissue cyst-forming coccidia|''Toxoplasma gondii'']]
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*Cats are definitive hosts but other species may become intermediate hosts if they ingest the oocysts
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*Usually induces antibody response but remains silent clinically
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*Often show clinical signs when immunosuppressed
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*Involves many different tissues
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*Multifocal necrotising [[Lungs - inflammatory#Interstitial pneumonia|interstitial pneumonia]]
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*Proliferation of type II pneumocytes
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*Macrophage and neutrophil infiltration
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===[[Metastrongyloidae|''Crenosoma vulpis'']]===
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*Mainly parasite of foxes but dogs may become infected from snails and slugs
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*Adults in [[Bronchi and bronchioles - inflammatory#Infectious causes of bronchitis or bronchiolitis|small bronchi and bronchioles]]
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*Grossly:
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**Greyish lesions and consolidation in dorsal aspect of caudal lung lobes
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*Histologically:
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**Catharral, eosinophilic bronchitis ans bronchiolitis
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==In Cats==
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*Useful websites:
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**[http://www.ivis.org/advances/Parasit_Bowman/ddb_resp/chapter_frm.asp?LA=1 Cat and dog respiratory parasites (part 1)] - Nasal Mucosa and Sinuses, and Respiratory Parenchyma
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**[http://www.ivis.org/advances/Parasit_Bowman/ddb_resp2/chapter_frm.asp Cat and dog respiratory parasites (part 2)] - Trachea and Bronchi, and Pulmonary Vessels
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===[[Crustacea|''Linguatula serrata'']]===
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*As in dogs above
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===[[Metastrongyloidae|''Aelurostrongylus abstrussus'']]===
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*Live in [[Lungs - inflammatory|lung parenchyma]] and [[Bronchi and bronchioles - inflammatory#Infectious causes of bronchitis or bronchiolitis|small bronchioles]]
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*Grossly:
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**Firm yellow nodules scattered throughout parenchyma, more frequently at periphery
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*Microscopically:
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**Eggs and larvae in the alveolar spaces cause a foreign body type reaction (surrounded by mononuclear cells and giant cells)
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**Submucosal gland hypertrophy and smooth muscle hypertrophy in airway and vessel walls
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*Associated clinical signs are mild although heavy infestations may -> chronic coughing
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*The airway eosinophilia which may be detected can be confused with a diagnosis of asthma
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===[[Filarioidea|''Dirofilaria immitis'']]===
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*As in dogs above
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*Not very infective in cats but one dead adult causes acute pulmonary crisis - [[Lungs - circulatory#Embolism, thrombosis and infarction|thromboembolism]]
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===[[Trichinelloidea|''Capillaria aerophila'']]===
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*As in dogs above
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==In Horses==
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===[[Ascaridoidea|''Parascaris equorum'']]===
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*Causes transient [[Nasal cavity - inflammatory#Infectious causes of rhinitis|nasal discharge]] when migrating through [[Lungs - inflammatory#Infectious causes of pneumonia|lungs]]
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**Foals and weanlings
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===[[Trichostrongyloidea|''Dictyocaulus arnfieldi'']]===
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*Found in smaller [[Bronchi and bronchioles - inflammatory#Infectious causes of bronchitis or bronchiolitis|bronchi]]
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*Cause of chronic cough
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*Donkeys are a reservoir mostly without any clinical signs
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*Gross pathology:
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**Raised areas of over-inflated pulmonary tissue surrounding small bronchus, containing worms and mucopurulent exudate
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**Hyperplastic bronchial epithelium
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**Coiled worms in small bronchi
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**Peribronchial cuffing
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**In caudal lung lobes
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*Histologically
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**Central coiled parasites and associated chronic catharral bronchitis
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**Goblet cell hyperplasia
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**Lymphoid cell infiltration
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*In [[Hindgut Fermenters - Horse - Anatomy & Physiology|horses]], the worms usually fail to achieve sexual maturity
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===[[Coccidia|''Besnoitia bennetti'']]===
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*Papilloma like lesions in [[Larynx - inflammatory#Infectious causes of laryngitis|larynx]], skin and sclera
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*Thick walled parasitic cysts, covered by hyperplastic epithelium, may be ulcerated
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==In Cattle==
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===[[Trichostrongyloidea|''Dictyocaulus viviparus'']]===
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[[Image:Dictyocaulus viviparus.jpg|right|thumb|100px|<small><center>Dictyocaulus viviparus (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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[[Image:Parasitic bronchitis.jpg|right|thumb|100px|<small><center>Parasitic bronchitis (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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*Found in [[Trachea - inflammatory#Infectious causes of tracheitis|trachea]] and [[Bronchi and bronchioles - inflammatory#Infectious causes of bronchitis or bronchiolitis|large bronchi]]
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*Causes parasitic bronchitis, synonyms: bovine dictyocauliosis, husk, hoose
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*Primary infection:
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**Penetration phase (week 1)
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***Larvae migrate to lungs, no clinical signs
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**Prepatent phase (weeks 1-3)
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***Development and migration of larvae -> [[Bronchi and bronchioles - inflammatory#Bronchiolitis|bronchiolitis]] -> eosinophilic exudate -> air passage blocked -> alveolar collapse (distal to blockage) -> clinical signs (tachypnoea, coughing)
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**Patent phase (weeks 4-8)
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***Egg-producing mature worms
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***[[Bronchi and bronchioles - inflammatory#Bronchitis|Bronchitis]] - due to mature worms
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***[[Lungs - inflammatory#Verminous pneumonia|Parasitic pneumonia]] - due to aspiration of eggs and larvae -> cellular infiltration of neutrophils, macrophages, giant cells
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**Postpatent phase (weeks 8-12)
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***Majority of worms are expelled
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***In 25% of cases clinical signs may reappear as a result of alveolar epithelialisation
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***May be together with [[Lungs - ventilation#Emphysema|interstitial emphysema]] and [[Lungs - circulatory#Pulmonary oedema|pulmonary oedema]], or secondary bacterial infection
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*Reinfection syndrome:
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**Immune cattle show clinical signs only if exposed to large numbers
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**Pathogenesis - large numbers of larvae reach bronchioles where they are killed by immune response
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**Pathology - parasite granulomata (grey-green, 5mm diameter, macrophages, giant cells, eosinophils) and eosinophilic plugs in bronchioles
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<small>Above from RVC Parasitology study guide (2005-2006)</small>
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*Preferentially in dorsocaudaland ventrocaudal regions
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*Histologically
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**Bronchial epithelium may show hyperplasia due to the chronic irritation
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**Cross-sections of the parasites
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**Exudate contains many eosinophils
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**Foci of necrosis in the rest of the lung tissue due to aspiration of eggs and larvae fromhese adults
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**In mild infestations, the adults are normally expelled in two months - self cure
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*Repeated infestation and secondary bacterial infection are common
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*Two other types of lesion in lung tissue due to this worm have been reported:
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**Nodules (2-4mm in diameter) with greenish centres in the reinfection of an immune animal - the host mounting a successful defence and preventing larval migration
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**Pulmonary oedema and emphysema - thought to be a hypersensitivity response to a massive invasion of larvae in previously- sensitised animals - the gross and microscopic appearance is similar to that of [[Lungs - inflammatory#Acute bovine pulmonary emphysema and oedema (ABPEE)|fog fever]]
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===Hydatid cysts===
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[[Image:Echinococcus cysts.jpg|right|thumb|100px|<small><center>Echinococcus cysts (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
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*The intermediate stage of [[Cestodes|''Echinococcus granulosus'']] can be found in the lungs of many species, most commonly in lungs of cattle and sheep
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*They range in size up to 5-10 cm diameter and although of little clinical significance, are important as a zoonosis (can be upto football size in man) and because of carcass condemnation
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===[[Strongyloidea|''Syngamus laryngeus'']]===
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*In [[Larynx - inflammatory#Infectious causes of laryngitis|larynx]] of cattle in Asia and South America
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==In Sheep==
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===Hydatid cysts===
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As in cattle (above)
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===[[Insecta|''Oestrus ovis'']]===
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*Larvae in the [[Nasal cavity - inflammatory#Infectious causes of rhinitis|nasal cavity]] of sheep and goats = Nasal bots
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*Causes reaction in [[Paranasal sinuses - inflammatory#Sinusitis|sinuses]]
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[[Media:Oestrus ovis.mp4]]
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===[[Metastrongyloidae|''Protostrongylus'' spp.]]===
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*Adult worms block small [[Bronchi and bronchioles - inflammatory#Infectious causes of bronchitis or bronchiolitis|bronchioles]] resulting in accumulation of eggs, larvae and cellular debri distal to the blockage
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*Lesions resemble [[Parasitic infections#Dictyocaulus filaria|''Dictyocaulus filaria'']] but are fewer in numbers, lobular and at periphery of caudal lobes, they are very similar to [[Parasitic infections#Muellerius capillaris|''Muellerius capillaris'']] lesions
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===[[Metastrongyloidae|''Muellerius capillaris'']]===
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*Common in sheep and goats
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*Rarely any clinical significance
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*Grossly:
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**Multifocal [[Lungs - inflammatory#Interstitial pneumonia|interstitial]] [[Lungs - inflammatory#Infectious causes of pneumonia|pneumonia]] grossly evident as firm "lead-shot" nodules throughout the parenchyma, often with enveloping granulomatous response
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**Early stages are reddish in colour, turning later to greyish green, may calcify
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**Mostly in dorsal region of caudal lung lobes
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*Histologically:
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**Damaged alveolar septa with mild fibrous thickening and lymphocytic infiltrate
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**In more developed host resistance, foci of eosinophils around larvae, hyperplastic epithelium, macrophages, giant cells
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**May be some calcification
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===[[Trichostrongyloidea|''Dictyocaulus filaria'']]===
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*Most susceptible when first exposed to contaminated pasture
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*Animals < 1 year old
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*Pathogenesis and pathology similar to [[Parasitic infections#Dictyocaulus viviparus|''Dictyocaulus viviparus'']] in cattle
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*[[Bronchi and bronchioles - inflammatory#Infectious causes of bronchitis or bronchiolitis|Bronchitis]]
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==In Pigs==
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===[[Metastrongyloidae|''Metastrongylus'' spp.]]===
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*Found in [[Bronchi and bronchioles - inflammatory#Infectious causes of bronchitis or bronchiolitis|bronchioles and smaller bronchi]]
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*Grossly:
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**Small grey nodules, especially along ventral border of caudal lobes
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**Adult worms in bronchi and bronchioles
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*Histologically:
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**Catarrhal and eosinophilic bronchitis and bronchiolitis
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**Possibly [[Lungs - ventilation#Atelectasis (Collapse)|atelectasis]]
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*Rarely becomes extensive
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*May transmit [[Respiratory Viral Infections - Pathology#Swine influenza|swine influenza]]
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===[[Ascaris suum|''Ascaris suum'']]===
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*May cause [[Lungs - inflammatory#Verminous pneumonia|parasitic pneumonia]] during a part of its migration
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*Larvae may be infected with [[Respiratory Viral Infections - Pathology#Swine influenza|Swine influenza]]
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*May cause severe pneumonia in calves housed where infected pigs were housed previously
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*Cause diffuse [[Lungs - inflammatory#Interstitial pneumonia|interstitial pneumonia]] with haemorrhage, [[Lungs - ventilation#Atelectasis (Collapse)|atelectasis]], [[Lungs - circulatory#Pulmonary oedema|interlobular oedema]] and [[Lungs - ventilation#Emphysema|emphysema]]
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