Exam 3 Complete Characteristics

Describe Stronglyloides Sterocalis

Threadworm

Can be direct or indirect

Final hosts: Dogs, cats, primates, humans

Intermediate Host: none

Located: Small intestine

Size: 2-3 mm in length

Lifecycle: Adult parasites are eaten, females lay ova, ova hatch in host’s small intestine, resulting first stage larvae pass into host feces. First stage larvae either develop into L2, then L3 infective third stage larvae or develop into non-parasitic, free living adults that produce more infective larvae. Then infective third stage larvae infect final host via cutaneous migration, Penetrate skin, to bloodstream, to lungs. Cough and swallow reflec- to the small intestine. Then continues development in wall of small intestine. Larvae then develop into adults, release ova which hatches in host animal

Prepatent pd: 2 weeks

Modes of Transmission: Cutaneous Migration & Transmammary

Clinical Signs: Chronic diarrhea, pruitis (especially feet)

Diagnosis: Fecal exams, ELSA testing for antibody response

Treatment: Improve Sanitation, Ivermectin, treat every 2 weeks for multiple treatments due to autoinfection larvae

Describe Strongyloides Sterocalis Autoinfection

L1 larvae develop into L2 then L3 infectious larvae within the gut of the host

Penetrate the intestinal wall, goes to the bloodstream, goes to the lungs, etc.

Describe Thelazia Californiensis

Worm Type: Eye worm

Lifecycle type: Indirect

Final hosts: Cats, dogs, sheep, cattle, humans

Intermediate Host: Various species of flies

Located: Conjunctival sac or tear duct

Lifecycle: Adult worms lay eggs in tear ducts/tears, eggs picked up by flies; develop into larvae within the flies, Larvae move to mouthparts of fly so they can exit to new host, develop to adulthood in the eye of the new host

Prepatent pd: 3-11 weeks

Modes of Transmission: Vector-borne

Clinical Signs: Conjunctivitis, eye irritation, Excessive tearing

Diagnosis: Finding adult worms in conjunctival sac, finding embryonated ova or first stage larvae in tears

Treatment: Removal, ivermectin and other drugs

Zoonotic potential: can infect humans

Describe Spirocerca Lupi

Worm Type: Esophageal worm

Lifecycle type: Indirect

Final hosts: Dogs, wild canines (mainly foxes)

Intermediate Host: Dung beetle

Located: Esophagus

Lifecycle: Final host ingests intermediate host, larvae released in stomach, Larvae migrate to aorta (develops in wall), then esophagus, Final hosts body tries to fight off larvae, cancerous nodules can form (fibrosarcoma) Adult worm develops, ova pass through feces, Intermediate host ingests ova; hatch

Prepatent pd: 3-6 months

Modes of Transmission: Paratenic host

Diagnosis: Can be challenging (Lay eggs sporadically so its difficult to see on floatations

Treatment: Dewormers (specialized types, normal ones won’t work), Surgical removal of large nodules (complex), Neoplastic form requires chemotherapy

Describe Dipylidium caninum

Worm Type: Tapeworm

Final hosts: Dogs, Cats, occasionally humans

Intermediate Host: Flea larvae and biting lice

Located: Small intestine

Size: 1-2 feet long (adults)

Lifecycle: The flea larvae and biting lice ingest the eggs discharges by shedding proglottids, eggs then hatch and develop into the cysticercoid within flea larvae or louse, flea/louse is ingested by the dog/cat, larvae evaginates in the intestine, attach too the wall and matures into adults

Describe Dirofilaria Immitis

Worm Type: Heartworm

Lifecycle type: Indirect

Final hosts: Dogs, rarely cats

Intermediate Host: Mosquito

Located: Pulmonary Artery and right side of the heart

Size: Long, round and thin

Lifecycle: Mosquito takes bloodmeal, ingests L1 microfilariae which develops into L2 then L3 within the mosquito, then they migrate to mosquitos salivary glands. Development and migration takes 10-14 days upwards of 30. Mosquito then bites uninfected host and L3 microfilaria is deposited into the wound. Inside the new host, the L3 develop to L4 (3-4 days) L4 migrate through the bloodstream to thoracic cavity; develop into L5 on the way (50-70 days). L5 reach pulmonary artery about 70 days post infection. Mature into adults, which in turn produce more microfilariae

Prepatent pd: 6-7 months (only after this time will the animal test positive for microfilariae)

Modes of Transmission: Vector-borne, Pre-natal transmission of microfilariae can occur - bitch ahs adult heart worms, microfilariae cross the placenta to puppies, puppies are born with L1 microfilariae, they do not develop into adults - no intermediate hosts. they can be considered a source of transmission if bitten by mosquito, but if not, the microfilariae will die off.

Clinical Signs: Early on can be asymptomatic, Chronic signs can be tires easily, hear murmur, right sided heart enlargement/ failure

Diagnosis: Variety of tests, Antigen testing common- identifies antigens from female worms in blood, supportive tests - CBC, biochemistry profiles, urinalysis, EKG, chest radiographs

Classifications:
Class 1 - Usually asymptomatic
Class 2 - minimal clinical signs
Class 3 - Animal has signs of heat failure
Class 4 - Caval syndrome; adult worms migrate back into vena cava/right atrium; surgery to remove, sudden shock like collapse, difficulty breathing, pale due to hemolysis

Prevention: Kill microfilariae- Microfilaricides, effective against L1-L4, examples: Ivermectin, Selemectin, Recommended year round

Treatment: L5 to adults - Adulticides, Caparsolate (outdated), Melarsomine (immiticide)

For Cats: Not commonly a final host, only 1-2 adults, microfilaria not produced, clinical signs: vomiting, cough, seizures, fluid accumulation in abdomen, sudden death. Diagnosis: Antigen testing, not always accurate because of low worm burden. Treatment is hard cause cats are sensitive

Zoonotic potential: termed “Dirofilariasis”, often don’t survive passage through tissues, if they do they don’t reach sexual maturation = no microfilariae, L5 can be found in lungs, inflammatory reactions (granulomas) often asymptomatic; but can see coughing, chest pain, fever, pleural effusion