|
 |
 |
 |
 |
|
|
|
|
|
|
Primarily parasites which reach the adult stage in this system will be fully discussed, however, some whose larvae migrates through the lungs are listed under their respective host and discussed later in the organ(s) in which they mature. A slide set of parasites of this system is provided in the AVAT Lab.
Location: Bronchioles
Cattle. Deer, Bison, Moose, Reindeer and Elk. Larvated eggs 82-88 x 33 - 38 microns. Infective stage in 4-6 days.
Life Cycle
Eggs pass in feces and hatch. There is very little migration of the larvae from the fecal pad. Rainfall and splattering diarrhea results in larvae getting into herbage. The fungus Pilobus may distrobute larvae about ten feet. Larvae, on being ingested, may reach the lungs in 24 hours in heavy infections. These worms mature with in 22 days after infection.
Pathogenesis:
Prepatent phase
Is characterized by blockage of many of the bronchioles with eosinophilic exudate and collapse of the alveoli. Symptoms are tachypnea and coughing. Emphysema may develop.
Patent infection:
Adult worms in bronchioles and trachea - marked exudation and severe damage to the epithelium of these organs - aspiration of larvae and eggs etc. into bronchioles and alveoli lead to consolidation of lobules.
Post-patent phase
Occurs in about 30 days after infection - phase of recovery - Symptoms subside - weight gain resumes worms are no longer present and lesions remaining consist of peribronchial fibrosis.
Possible complications are:
Acute pulmonary pneumonia and acute pulmonary edema are frequently observed in heavy infections in the adult, partially immune host; Similar to "fog fever".
Immunity:
Begin in 10 days. Artificial vaccination - 2 doses of 1000 irradiated larvae given atal month interval.
Diagnosis:
Larvated eggs or larvae in feces. Increased incidence of coughing in herd which has been placed on pasture. "Husk" as a herd problem seen especially in calves.
Rules-outs:
Virus pneumonia, Pasteurella infection, epizootic pneumonia, cuffing pneumonia.
"Hookworm" Nematode See intestine - Migrating phase
"Ascarid" "roundworm" Nematode - See intestine - Migrating phase
"Threadworm" Nematode - See intestine - Migrating phase
"Hydatid cyst" Cestode Migrating larvae in intermediate host (See intestine of caridae for adult stages)
(Brown intestinal granules in larvae is diagnostic seen in egg also)Location:
Bronchioles
Host:
Sheep, goats and some wild ruminants. Adults are milk white in color - 4 small lips - spicules are stout, dark brown, foot-shaped are .4 - 64 mm long. Vulva behind middle of body. Larvated eggs 112 - 138 x 69 microns and larvated - may hatch in lungs. Some eggs expelled in nasal exudate. Larvae possess a cuticular knob at anterior extremity. Numerous brownish granules in intestine of larvae larvae become infective in 6-7 days. Infection per os. Larvae penetrate intestinal wall in 3 days and pass to mesenteric lymphodes where the larvae molt and develop to L4 with in 4 days after infection. L4 pass from lymph vessels to blood stream then to lungs where they are arrested in the capillaries. Larvae reach lungs in 14 days. Longevity for majority of worms is from 50-70 days. They break out into air passages and mature in 4 weeks.
Symptoms:
Cough (not always present), tenacious mucous exudate from nostrils, dyspnea, rapid breathing, abnormal lung sounds, infrequent diarrhea.
Lesions:
Catarrhal parasitic bronchitis and pneumonia, atelectasis
Be- longs to the family hair- like appearance. Found in bronchioles, alveoli, and parenchyma of lung.Posterior end of male is spirally coiled.
Host:
Sheep and goats.
Life Cycle
Indirect - eggs develop in lungs and first stage larvae (L1) pass in feces - Larvae possess a on an (diagnostic).
Intermediate hosts:
Species of nude snails (Limax, Helix)
Pathogenesis:
Greyish nodules 2 cm which consist of necrotic masses, accumulations of leukocytes, and pulmonary connective tissue with infiltration of giant cells, Nodules calcify.
Hosts:
Sheep and deer
Tail-tip of first stage (L1) is larvae wavey (diagnostic).
Life Cycle
Indirect - Intermediate host is the Snail Theba, Abida, Zebrina and Helicella - Larvae infective in 12 - 14 days.
Diagnosis:
Larvae in feces.
Hosts:
Sheep and goats (65mm). Nematode "Hookworm" see intestine.
Hosts:
"Nodular worm" Nematode Lungs (erratically) sheep, goats antelope.
Cestode-Lungs (erratically) more common in other visceral organs-Intermediate hosts: sheep, goat, cattle, swine, man, horse (rarely) see intestine of primary hosts: Canine and Feline.
Nematode (60-120mm long). Principal hosts are mule deer and the blacktail deer of the Western and Southern USA and the white tail deer in the Southeastern Region - Sheep and goat populations often become infected in endemic areas. Principal location. Adults are found in carotid and internal maxillary, and brachial arteries.
Involve flies (Tabamus, Hybomitra) in which the infective larvae develop in 2 weeks - adults develop in 3 weeks after infection. The microfilariae measure 275 microns by 17 microns thick and cause a bloody raw dermatitis in pole, forehead or face (sorehead) after 6-10 months lesions may also be seen in legs, feet or abdominal regions clear-eyed" blindness is related to brain lesions with leptomeningeal arterioles involved - symptoms of circling, incoordination, convulsions, opisthotonis and death.Diagnosis:
(Differential) Necropsy or demonstrate microfilariae in lesions (biopsy) see textbook.
Piperazine salts 100 mg/lb body wt. orally - no treatment for CNS form - Trolene - DOW-ET.57 300 mg/kg.
Dipterous insect. Adults are dark gray with small black prominent spots on thorax and are covered with light brown hair. They hide in warm corners and crevices. Occur in spring to autumn, especially summer. Larvae in nasal cavity and adjoining sinuses in sheep, rarely goats -also camel (eyes, lips, nostrils of man, serious in man).Life Cycle
Adult female flies deposit larvae around nostrils where they crawl upward into turbinates and frontal sinuses. (some die here if unable to get out). The larvae remain in sinuses from 2 weeks in warm climates to 9 months in cold climates (first instar). Second instar develop rapidly leaving the host 25 days after infection; fully grown larvae crawl out of nasal cavity, pupate in 3-6 weeks (in ground) or longer, before fly emerges.
At first, the larvae are white or slightly yellow - mature larvae have dark transverse ridges on dorsal aspect of each segment.
Pathogenesis:
Great annoyance by flies causes rest- lessness and animals to stop feeding. The larvae cause a viscid mucous nasal exudate and sneezing due to the oral hooks and spires, erosion of bones of the skull, injury to brain, high stepping gait and incoordi- nation ("false gid"). "True gid" is caused by Coenurus cerebralis within the cranial cavity.
Diagnosis made on the basis of clinical signs of which other pulmonary diseases have to be considered.
Treatment
Ivermectin
The above fly belongs to the family Oestridae which includes a group of large, non-parasitic adult flies whose larvae are parasitic. The adults are hairy flies with rudimentary mouth parts. The adult females usually lay eggs or larvae on their host. Larvae are parasitic maggots with 12 segments - first two have fused oral hooks, but no head.
Larvae molt twice during their parasitic life and leave the host when they are fully grown to pupate in the ground. The larvae feed on the body fluids of host or on the exudate which surrounds them.
Species which are of veterinary importance are as follows:
a. Bots in horses stomach -(Gastrophilus)
Gastrphilidae
b. Nose bot in nostrils of sheep - (Oestrus) Oestridae
Oestridae
c. Cattle grubs - subcutis and skin - (Hypoderma)
Hypodermatidae
d. Rodent bot - subcutis and skin (Cuterebra)
Cuterebridae
Family Cuterebridae occurs in man and animals of tropical America and Mexico to Agrentina. Genus Cuterebra larvae are seen in the subcutis of rodents (rabbits, rats) Sometimes cats, dogs and even man may become infected.
Symptoms are related to the number of flukes present in airpassages.Treatment - Unknown.
