Lungworms Flashcards
Lungworm classification
Phylum: Nematoda Order: Strongylida Superfamily: Trichostrongyloidea - Dictyocalus viviparous (cattle and deer) - Dictyocalus filaria (sheep, goats) Superfamily: Metastrongyloidea - Muellerius capillaris (sheep, goats) - Aelurostrongylus abstrusus (felids) - Filaroides osleri (canids)
Dictyocaulus viviparus - hosts
DH: cattle, deer, elk, bison
- sites: trachea, bronchi, bronchioles
Dictyocaulus viviparus - life cycle
External environment (4-6 days) - L1 in feces --> L2 --> L3 ingested alone or on Pilobolus fungus --> L3 penetrates SI, mesenteric LN --> L4 thoracic duct and right heart, lung, alveoli --> +/- ALD --> adults in lumen of bronchial tree --> eggs embryonate (coughed up. swallowed) --> L1 usually hatch in airway or GIT
Pilobolus
Commonly grows on herbivore manure
- larval lungworm nematodes excreted by host, climb up Philobolus sporangiophores –> discharged with sporangium
- exploding fungi spores cast larvae for long distances from cow paddy
- nematodes complete life cycle when they are ingested by new host
Dictyocaulus viviparus - pathology
- inflammation of bronchi, plug of eosinophils obstructing small bronhiole
- collapsed alveoli
- epithelialized alveoli
- fibrotic lobes
Dictyocaulus viviparus - adult pathology
Moderate to heavy infection
- impaired respiratory function
- death
- infections in deer appear to be associated with cross-contamination with infected domestic species (problem in cattle near deer)
Dictyocaulus viviparus - clinical signs
- respiratory: chronic bronchitis, tachypnea, severe dyspnea, extended head, harsh cough
- anorexia
- emaciation
- death
Dictyocaulus viviparus - diagnosis
L1 in feces!!
- only L1 of parasitic nematodes found in fresh cattle manure
- prominent granules, bluntly pointed tail, rounded head, granules
- males are bursate
- use Baermann with fresh feces!!
Dictyocaulus viviparus - treatment and control
- labeled for cattle: fenbendazole, albendazole, oxfendazole
- vaccine in Europe
- -> disadvantages: short shelf life, radiation attenuated, has to be produced annually, uses donor calves, calves must be boosted from natural challenge to maintain protective immunity
Dictyocaulus filaria - hosts
DH: sheep, goats
- sites: bronchi and trachea
- distribution: worldwide, US (NE, central)
Dictyocaulus filaria - life cycle
External environment (6-7 days) –> L1 in feces –> L2 –> L3 ensheathed infective stage –> L3 ingested –> L3 penetrates SI, mesenteric LN –> L4 thoracic duct and right heart, lung, alveoli –> +/- ALD, can arrest in L4 or early adults –> adults in lumen of bronchial tree –> eggs embryonate (cough/swallow) –> L1 usually hatch in airway or GIT
Dictyocaulus filaria - pathology
- inflammation
- catarrhal bronchitis
- atelectasis
- pneumonia
Dictyocaulus filaria - clinical signs
Usually mild, unless large infections
- respiratory: cough, nasal discharge, tachypnea, dyspnea
- weight loss
- febrile with secondary infections
Dictyocaulus filaria - diagnosis
L1 in fresh feces - bluntly pointed end - brownish intestinal granules - button at mouth - Baermann - adults on necropsy Eggs from sputum/nasal discharge (fully larvated)
Dictyocaulus filaria - treatment and control
Labeled for sheep: Albendazole, levamisole, ivermectin, fenbendazole (goats)
- management: avoid moist or contaminated pastures
Muellerius capillaris - host
DH: sheep, goats
IH: gastropods (snail, slug)
- site: lungs (parenchyma, bronchioles)
- distribution: worldwide, US
Muellerius capillaris - life cycle
L1 in feces –> L1 penetrates IH or is swallowed –> L2 –> L3 (infective) –> DH ingests IH –> L3 penetrates gut –> mesenteric LN, heart and lungs –> L4 lung parenchyma –> forms nodules –> adults in nodules in lung parenchyma –> eggs in lung parenchyma –> L1 hatch in lungs –> coughed up and swallowed
Muellerius capillaris pathology
Not usually pathogenic
- inflammation
- small nodular lesions
Muellerius capillaris - diagnosis
L1 in feces
- Baermann technique of choice
- wavy, pointed tail with dorsal spine!!
Muellerius capillaris - treatment and control
Generally not treated
- could use off label dewormers
Aelurstongylus abstrusus - hosts
DH: cats
IH: snails, slugs
PH: rodents, birds, amphibians, reptiles
- site: lung parenchyma, terminal respiratory bronchioles, alveolar ducts in nodules
Aelurostrongylus abstrusus - pathology
- subpleural nodules
- smooth muscle hypertrophy
- milky lung exudate with eggs and larvae
Aelurostrongylus abstrusus - clinical signs
Respiratory
- severe pulmonary disease
- coughing
- tachypnea
- dyspnea
- sneezing
- nasal discharge
Aelurostrongylus abstrusus - diagnosis
L1 in fresh feces
- tail curved, dorsal spine
- Baermann
Adults are thread like
Aelurostrongylus abstrusus - treatment and control
Off label: fenbendazole, ivermectin
- management: prevent ingestion of intermediate or paratenic host
Filaroides osleri - hosts
DH: canids, including wild canids
- site: in nodules and trachea and bronchi!
- rarely in lungs!!!
Filaroides osleri - life cycle
L1 and eggs in feces and saliva –> prepatent period of 10 weeks –> DH ingests L1 or L1 in egg –> lymphatic and venous portal systems –> L1-L4 –> migrates to heart and lungs, bronchi, tracheal bifurcation –> adults in nodules in trachea and bronchi
- eggs: larvated, shed in respiratory tract
Filaroides osleri - clinical signs
- chronic dry cough
- severe respiratory distress
- emaciation
Filaroides osleri - pathology
Nodules in bifurcation of trachea
Filaroides osleri - diagnosis
L1: wavy tail kinked, no dorsal spine
- ZnSO4 flotation, NOT Baermann!
Direct smears: confirm by bronchoscopy, lesions observed by bronchoscope are pathognomonic
Filaroides osleri - treatment
Off label: ivermectin, fenbendazole
- successful chemotherapy
- nodules resolve, clinical signs disappear, disappearance of larvae from feces
