2. Characteristics
⢠Most worms in this superfamily inhabit the lungs
or the blood vessels adjacent to the lungs.
⢠The typical life cycle is indirect, and the
intermediate host is usually a mollusk.
3. Oslerus osleri (TRACHEAL WORM)
Definitive Host Spectrum
⢠Canids
Geographic Distribution
⢠Worldwide, but low prevalence
Morphology
⢠Adults - males 5 mm, females 9-15 mm
⢠Eggs - larvated, 80 x 50 microns, hatch before
passing in feces
⢠Larvae - 232-266 microns, with S-shaped tail
4. Life Cycle (Stages)
⢠L 1 are passed in feces or saliva
⢠These L 1 are immediately infective
⢠Major modes of transmission are by the bitch
licking her pups, fecal contamination, licking of
mouth, and feeding by regurgitation (wild
canids)
⢠Once acquired larvae migrate to the trachea via
the lymphatic and venous portal systems
⢠Prepatent period - 6-7 mos.
5. Site of Infection
⢠Trachea and bronchi
Pathogenesis/Clinical Signs
⢠Adult worms live in or under the tracheal or
bronchial mucosa and cause grayish-pink
fibrous nodules to develop which cause a cough.
⢠These granulomas are usually less than 1 cm in
diameter
⢠Clinical signs - cough, dyspnea, anorexia,
emaciation
⢠Usually a chronic disease of young dogs, but
can be fatal
6. Diagnosis
⢠Bronchoscopy - nodules at the bifurcation of the
trachea (predilection site)
⢠Typical larvae in feces, tracheal swabs or sputum - in
feces they are neither plentiful nor very active
⢠Thoracic radiography
Treatment
⢠No satisfactory treatment - can try levamisole,
albendazole, fenbendazole or avermectins (cautionary
in dogs)
Other control Measures
⢠Remove pups by caesarian section and raise them in
isolation but not practical;
7. Filaroides hirthi (LUNGWORM)
Definitive Host Spectrum
â Canids
Geographic Distribution
â Eastern US, Texas
Morphology
â Adults - males 2-3 mm, females 6.6-13 mm
â Larvae - 240-290 microns long
Life Cycle (Stages)
â Similar to F. osleri
â Prepatent period - 5 weeks
8. Site of Infection: Lung parenchyma
Pathogenesis/Clinical Signs
⢠Focal granulomatous reaction
⢠Usually no clinical disease
⢠Fatalities have occurred in severely stressed or
immune deficient dogs
Diagnosis
⢠Finding larvae in feces - zinc sulfate flotation is better
than Baermann technique
⢠Usually diagnosed post mortem
Treatment
⢠Albendazole
⢠fenbendazole
9. Aelurostrongylus abstrusus (CAT LUNGWORM)
Definitive Host Spectrum
⢠Felids
Intermediate Host
⢠Snails
⢠Rodents, frogs, lizards and birds may serve as paratenic
hosts
Geographic Distribution
⢠Worldwide; in the US, southern states
Morphology
⢠Adults - rarely seen intact because they are deeply
imbedded in tissue; males up to 7 mm, females up to 10
mm
⢠Larvae - about 360 microns, tail has a double bend and a
dorsal spine
10. Life Cycle (Stages)
⢠Eggs are laid by females, L 1 hatch and are carried up the
bronchial tree and are swallowed and passed in feces
⢠Larvae penetrate IH and undergo 2 molts
⢠Cats acquire the infection either by eating snails or by eating
the paratenic host which has eaten an infected snail
⢠Larvae migrate from the stomach to the lungs through the
peritoneal and thoracic cavities
⢠Prepatent period - 4 to 6 weeks
Site of Infection
⢠Terminal bronchioles and lung parenchyma
11. Pathogenesis/Clinical Signs
⢠Usually nonpathogenic
⢠Lesions are subpleural grayish nodules which are firm, raised,
and 1-10 mm in diameter
⢠The parasite causes smooth muscle hypertrophy of the
bronchioles, alveolar ducts and tunica media of the small
arteries as well as hyperplasia.
⢠Clinical signs - usually none; in heavy infections cough,
dyspnea, emaciation, nasal discharge and sneezing
Diagnosis
⢠Typical L 1 in feces
⢠Radiographic evidence includes bronchial, alveolar disease and
pulmonary artery hypertrophy (PAH)
Treatment
⢠Fenbendazole
Other Control Measures
⢠Impractical, try to stop ingestion of intermediate or transport
hosts
12. Protostrongylus rufescens (RED LUNGWORM)
Definitive Host Spectrum: Sheep, goats,
Intermediate Host : Snails (several genera)
Geographic Distribution
â North America, Europe, Africa, Australia
Morphology
â Adults - slender, reddish, males 16-28 mm, females 25-35
mm
â Larvae - 250 to 340 microns; tip of tail has wavy outline, but
no spine
Life Cycle (Stages)
â Larvae (L 1 ) are passed in feces
â L 1 penetrate snails
â 2 molts in snail
â DH ingests snails while grazing
â Migration to the lungs via mesenteric lymph glands and
circulation
â Transplacental transmission occurs
â Prepatent period - 30 to 37 days
13. Site of Infection
â Small bronchioles
Pathogenesis/Clinical Signs
â Worms produce local inflammation of small bronchioles
â Exudate fills alveoli distal to the parasites
â The affected alveolar and bronchiolar epithelium is
desquamated, blood vessels are occluded and infiltration
with round cells occurs resulting in a small focus of lobular
pneumonia
â 2 o bacterial infections possible
â Usually no definite clinical signs
14. Diagnosis
⢠Finding larvae in feces
Treatment
⢠Levamisole, fenbendazole, ivermectin, doramectin
Other Control Measures
⢠Keep lambs off pastures previously used by infected
animals
⢠Salt blocks or range cubes containing anthelmintics
⢠Molluscicides
15. Muellerius capillaris (HAIR LUNGWORM)
Definitive Host Spectrum
Sheep, goats,
Intermediate Host
Snails ( Helix , Succinea )
Geographic Distribution
Worldwide, not of major importance in the US
Morphology
Adults - delicate, threadlike; males 12-14 mm, females 19-23 mm
Larvae - 230-300 microns, tip of tail wavy and with a dorsal spine
Life Cycle
L 1 are passed in feces
L 1 penetrate IH or are ingested
2 molts in IH
DH ingests snail or slug while grazing
Migration to lungs via lymphatics
Prepatent period - about 6 weeks
16. First larva of Muellerius
capillaries; whole larva
(A); anterior end (B);
posterior end (C);
wavy tip of the tail with a
dorsal spine
17. Site of Infection
â Alveoli and lung parenchyma, terminal bronchioles
â Pathogenesis/Clinical Signs
â Worms produce grayish nodules up to 2 cm in diameter,
consisting of degenerating leucocytes and pulmonary tissue
â Nodules may calcify
â Occasionally, adenoma-like proliferation of bronchial
epithelium is seen
â 2 o bacterial infection of the nodules may occur; nodules
may coalesce to form septic lesions
â Usually no clinical signs, but in heavily infected goats
coughing and dyspnea may occur
â Diagnosis
â Finding L 1 in feces
â Treatment
â Try repeated doses of fenbendazole, or avermectin class
â Other Control Measures
â Same as for Protostrongylus ; also spreading lime to kill
snails