Cerebrospinal Nematodiasis

Neural Larva Migrans

Invasion of the brain/spinal cord by nematodes

Invasion of the brain/spinal cord by helminth larvae

Parelaphostrongylus tenuis

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Neurotropic Nematode

• "meningeal worm" of white tailed deer
• cranial subdural space and venous sinuses of white-tailed deer
• eggs laid in venous circulation, embolic to lungs, develope and hatch, L1 shed in feces
• Indirect LC
• snails/slugs as IH→ingestion→L3 penetrate abomasum→enter peritoneal cavity→follow lumbar nervese to vertebral cnal→enter spinal cord→develope in cord→subadults enter spinal subdural space and mature→migrate to cranium
• Clinically silent in white tailed deer (normal host)
• In moose, elk, other cervids, sheep and goats, llamas, a variety of neurological signs due to spinal cord and brain damage
• Horse
• Aquired scoliosis in mature horses and donkeys, sudden curvature of the back. Spinal cord lesions causees loss of sensation on one side
• Dx- white tailed deer L1 shed in feces, S-shaped tail with dorsal spine
• Tx- Fenbendazole, diethylcarbamazine, ivermectin (every 3 wks for prevention)

Angiostrongylus cantonensis

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Neurotropic Nematode

• "rat lungworm"
• South Pacific islands, southeast Asia
• Fatal eosinophilic meningoencephalitis
• in humans, subhuman primates and dogs
• Rats
• adults in pulmonary arteries→L1 shed in feces
• snails/slugs IH, with wide variety of PH- prawns, crabs, planarians, frogs, giant African snails
• Indirect LC
• ingestion→olbigatory migration to brain→CNS developmnet for 2 wks→then via subarchnioid space and venous system→enter pulmonary arteries
• Human infection
• infection from eating raw improperly cooked snails, slugs, prawns, crabs, ect.
• migration not complete, remains in CNS
• Tx- dogs with MBZ, levamisole had high mortality post Tx

Strongylus vulgaris

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Accidental Parasite of CNS

• large strongyle of horses, cause verminous arteritis
• can cause CNS damage in horse
• normal migration
• migration to proximal cranial mesenteric artery, also can migrate to aorta, heart, carotids
• larva in anterior vessels gain access to brain, migrate in neuropil
• cause large migration tracks in CNS
• CNS signs
• paresis, sensory deficits, ataxia, signs may change with migration

Halicephalobus gingivalis

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Accidental Nematode of CNS

• free-living nematodes in soil, manure, other organic matter
• CNS disease in horses
• Pathology
• enters through oral cavity, nasal passage, wounds→penetration of head tissues> associated with maxillary granulomas, nassal masses, dissemination to brain, kidneys, ect
• Invastion of CNS causes focal to generalized encephalitis, clinical CNS disease
• Adults extremely small with rhabditiform esophagus

• most important accidental parasites of the nervous system
• typically occurs in normal and atypical PH
• following pulmonary migration> reenter venous system in lungs, through heart, distributed systemically, including CNS
• Causes
• visceral, ocular, neural larva migrans, w/disease varying with pathogenic characteristics of specis

Baylisascaris procyonis

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most pathogenic and most often incriminated in fatal or severe CNS disease

• associated with NLM, VLM, OLM in many animal species including man
• fatal CNS disease in >125 species of mammals and birds in N. America
• Sourses of Infection
• cages, areas, enclosures which previously held raccoons
• areas contaminated with raccone feces
• dirty straw or hay , contaminated feed
• very pathogenic to humans

Thelazia spp.

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Nematode of Eye

• "eyeworms" of mammals and birds
• Adults
• cuticle w/ prominent transverse striations
• found in conjunctival sac, under nictitating membrane, in lacrimal gland and duct, nictitating membrane gland, and nasolacrimal duct
• Indirect LC
• ovoviviparous females deposite thin-shelled eggs with L1 in ocular secretions> ingested by muscid fly IH> develope to L3> larva leave fly and reenter eye
• Clinical signs
• usually subclinical with mild signs, corneal irritation, conjunctivitis, lacrimation, photophobia, heavy infections w/ seromucoid exudate, corneal opacity, ulceration
• predisposes eye to other infections (pink eye)
• Dx- clinical signs, worms on cornea or periorbital hair
• Tx- control, topical anesthesia and removal by irrigation, control flies

Onchocerca sp.

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Nematode of the Eye

Integumentary Nematode

• found in ligamentum nuchae of horses
• "sweet itch", "Queensland itch" - Onchocerca cervicalis
• Culicoides vector, microfilariae have been implicated as contributing to "periodic ophthalmia", "recurrent uveitis"
• recurrent inflammation of one or both eyes
• Tx- conjunctival biopsy/wet mount for microfilariae
• ivermectin, moxidectin, may see belly edema w/in 24 hours due to reactions to dying larvae
• decrease ocular inflammation with steroids, then treat with ivermectin

Toxocara canis. T. cati

Baylisascaris procyonis

Baylisascaris primary cause of "large nematode variant" of diffuse unilateral subacute neuroretinitis (DUSN) in man

Toxocara recognized cause of "small nematode varient" of DUSN

Miscellaneous Nematodes

Intraocular Filarial Worms

Dirofilaria immitis- dogs

Setaria equina- horses

must be removed by surgical removal

Granular nodules on conjunctiva, especially at medial canthus, conjunctivitis, blepharitis, corneal irritation/keratitis

Pearsonema

(formerly Capillaria)

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Urogenital Nemotode

• Urinary bladder of carnivors
• Pearsonema plica- dogs, wolves, fox, mustelids, procyonids
• Pearsonema feliscati- cats
• Adults
• embedded in irinary bladder mucosa, eggs shed in urine, develope L1
• Indirect LC
• earthworm PH> in which eggs hatch> ingestion of earthworm> L1s penetrate intestine> enter bladder
• eggs- elongated barrel-shaped, colorless to light yellowish, w/ flattened bipolar plugs, rough, netlike surface
• Clinical
• not usually clinical, heavy infection can allow formation of bacterial cystitis
• Tx- ivermectin, fenbendazole, levamisole

Dioctophyme renale

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Urogenital Nematode

• "giant kidney worm" of carnivores- MINK
• Info
• largest nematode of domestic animals
• red color, transverse striations, 6 oral papillae, bell shaped bursa in males, found in kidney or body cavity
• Indirect LC
• eggs shed in urine>develop L1>consumed by aquatic oligochaetes IH> develop to infective L3>various fish, frogs are PH> ingestionof IH or PH> penetrate stomach wall or duodenum> enter peritoneum or kidney
• usually only affect right kidney
• Renal Infection
• hemorrhage, proliferative hyperplasia, eventual complete destruction of kidney, occasional ureter destruction
• Peritoneal infection
• peritonitis, hemorrhage adhesions, traumatic damage to liver, egg deposition in body cavity
• Egg
• barrel-shaped, yellow-brown color, thick, heavily pitted shell, indistinct polar plugs
• Tx- prevention, surgical removal, prevent ingestion of raw fish

Genital System

Transplacental transmission

Genital System

Transmammary transmission of nematode larvae (3)

Ancylostoma caninum

Toxocara canis

Strongyloides westeri

Trichinella spp

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Musculoskeletal Nematode

• "trichina worm" of man and animals- trichinellosis
• Trichinella spiralis- swine, rats, temperate, cosmopolitan
• Indirect LC
• transmission via carnivorism
• encysted L1 larvae in muscle> ingested> rapidly form adults in small intestine> female discharges prelarvae which enter lymphatics, vasculature> encyst in skeletal muscle> grow and become encysted L1
• Redifferentiation of myofiber
• larva orchestrates differentiation of myofiber into a "nurse cell", which serves its needs for nutrition
• Day 0-1:  initial growth phase of larva in myofiber
• Day 1-3:  lag phase, initial myofiber alterations
• Day 3-19:  exponential growth and major myofiber alterations
• Day 20+:  maturation, chemical and structural stability of NC
• Alterations yield increased absorptive capacity for nutrients for larvae
• Sylvatic cycle- predation and scavenging by wild carnivores and omnivores, may cross over into domestic cycle
• Domestic cycle- swine and rats primarily; and dogs, cats; maintained in swine herds by cannibalism and rat-rat, pig-rat cycle
• Information/ Facts
• Human infection primarily from ingestion of wild meat, especially bears, walrus, and from pork products
• T. spiralis has high infectivity for both swine and rats, and no resistance to freezing
• T. nativa has high resistance to freezing
• T. britovi and T. nelsoni have low infectivity and low resitance to freezing

Trichinella spp (part 2)

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zoonosis, treatment, prevention

• zoonosis
• has decreased from regulations on garbage feeding to swine, swine husbandry practices, public education, trichina-free pork programs
• No federal meat inspectin for trichinosis in US
• heavy infection may cause clinical disease in man and animals
• Intestinal infection- enteritis w/ nausea, vomiting, fever, GI pain, diarrhea
• Muscle invasion- interstitial myositis which subsides with nurse cell formation
• Tx- steroids, anthelmintics (mebendazole, albendazole), supportive treatment
• Prevention/ Control
• decrease uncooked garbage feeding to swine, avoid meat scraps, animal carcasses
• cooking, freezing pork, avoid wild meats
• T. nativa- freeze resistant
• microwaving tends to be unreliable (cold spots)
• gamma irradiation of pork products

Larva Migrans in Musculoskeletal System

3 nematodes

• Ancylostoma caninum
• somatic migration and arrested development in muscles of definitive and paratenic host species
• initial myofiber invasion by larva
• Baylisascaris spp., Toxocara spp.
• migration of larvae into somatic musculature of IH and PH
• formation of larva granulomas

Ischemic myopathy

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• Dirofilariasis- Dirofilaria immitis
• occasionally develops in peripheral arteries of dogs, especially posterior aorta, external iliac, femoral arteries serving real leg
• causes extensive ischemic necrosis
• Yellow-brown mottling of real leg muscles with scattered ecchymotic hemorrhages in fascia, clumps of heartworms in arteries and small branches in leg musculature

• Spirocerca lupi
• HPO- long bones, periosteal proliferation, long-standing or severe infections with masses in the thorax
• either large Spirocerca nodules or worm-induced fibrosarcomas and osteosarcomas of the esophagus, aorta

Dracunculus spp.

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Integumenary Nematode

• "guinea worms" of animals and man, SQ
• Dracunculus insignis- raccon, mustelids, wild canids, dogs, N. America
• Adults
• In SQ tissues, without well-developed mouth or lips; vulva, anus atrophic; prominent perioral papillae
• adults present in subQ of thorax, abdomen, inguinal regin, legs of animals
• Indirect LC
• copepod IH, frogs PH> femal induces blister and ulcer under the skin> contact with water> female protrudes and ruptures uterus> discharges L1 larva into water> eaten by copepod IH> ingestion of IH> young worms migrate/develop in connective tissues, subcutis, males die after fertilization
• D. medinensis- the "guinea worm", probable precursor of staff of Aesculapisus, god of medicine
• Female worms
• Hypersensitivity sevelops to worms (from secretions, uterine discharges)> localized or systemic reaction if worm broken during removal
• Dx- clinical signs
• L1 larva, long filiform tail (about 1/3 length), rhabditiform esophagus, transversely striated cuticle
• Tx- careful extraction or surgical removal, don't break the worm

Rhabditis strongyloides

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Integumentary Nematode

• free-living nematode, larvae a facultative cause of rhabditic dermatitis in animals
• Adults
• prominent rhabditiform esophagus
• lives in moist soil, manure, decaying straw bedding, other organic material
• Direct LC
• with eggs, larva, adults
• animal infected through association with damp bedding
• Causes
• superficial skin infestation with slight invasion, primarily in dogs, cattle
• Erythermatous dermatitis with depilation, pustule formation, thickening of skin, exudation with encrustation
• Dx- larvae (sometimes adults) in skin scrapings, will reproduce on nutrient agar
• Tx- topical astringents, anthelmintics/insecticides
• sanitation, clean, dry bedding important for control

Cutaneous Habronemiasis

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• granulomatous dermatitis of horses caused by larve of equine stomach worms
• Draschia, Habronema spp.
• LC
• Infected house/stable fly IH feeds at wounds, mucosal membranes, irritated areas> L3 larvae exit stomach worm> enter dermal tissues> provoke intense granulomatous inflammatory reaction
• causes variable-sized, non-healing, ulcerated granulomas which can progress to quite large areas
• frequently involves face, abdomen, legs, prepuce/penis, conjunctiva
• Dx- characteristic lesion, associated with fly season, skin scrapings
• Tx- ivermectin, fly control, surgical excision or tissue

Miscellaneous Subcutaneous filarioids

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Dipetalonema reconditum- dogs; fleas, lice

Dirofilaria tenuis-raccon

Cercopithifilaria grassi- dogs

Onchocerca volvulus- man

Splendidofilaria fallisensis-ducks

Nematode Larval Skin Penetration

penetration dermatitis

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• Hookworm dermatitis
• Ancylostoma caninum, A. braziliense, Uncinaria stenocephala, Bunostomum spp
• especially pododermatitis of dogs due to A. caninum
• Strongyloides spp
• S. stercoralis, S. ransomi
• cutaneous larval migrans (CLM)
• in man due to Ancylostoma spp., Bunostomum spp., Strongyloides spp., gnathostomes, ect.

Paragonimus kellicotti

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Trematode of Respiratory System

• "lung fluke" of dogs, cats, wild canids, mustelids, raccons, N. America
• Large, reddish-brown, globular flukes
• spinous tegument, acetabulum just anterior to midbody, occuring in pairs in cysts in the lungs
• Indirect LC
• aquatic snails as 1st IH> cercariae leave snails> penetrate and encyst in crayfish (2nd IH)> metacercariae develop> crayfish ingested> metacercariae exit and penetrate intestine> migrate 2 wks in peritoneal cavity> penetrate diaphragm> enter lungs> encyst in lungs
• seasonal life cycle- most cercariae enter the encyst in crayfish in the summer and fall
• Prepatent period
• early migratory damage to liver, diaphragm, lungs from young flukes> eosinophilic peritonitis, hepatitis, pleuritis, myositis, can go to CNS
• weight loss, anorexia, lethargy cronic cough
• Dx- eggs in feces, sputum, transtracheal wash (eggs heavy, need SG right)
• eggs- broadly ovoid, golden brown, operculated; operculum flattened with prominent shoulders; abopercular eggshell thickened; unembryonated
• radiograph will see air-containing cysts in lung field
• Tx- Fenbendazole, albendazole, praziquantel, prevent eating of crayfish

Schistosomes

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Blood Flukes

Heterobilharzia americana- raccoons, dogs, bobcats, ect.

• Located in mesenteric veins (most species), some in urinary plexus veins, nasal veins, dorsal aorta
• Adults
• small elongate flukes, separate sexes, male with gynecophoric canal to hold female
• Indirect LC
• eggs shed in veins> work their way through intestinal or urinary bladder mucosa (aid of enzymes, spines> voided in feces or urine> miracidium hatches> penetrates aquatic snail> goes through 2 sporocyst generations> forked-tail cercariae shed in large numbers> penetrate skin> enter circulation> migrate through lungs> enter liver, portal veins, then mesenteric veins
• young migratory flukes called schistosomule
• Disease States
• produced by egg deposition in organs and tissues
• Acute- heavy infections, massive egg deposition in intestinal wall, diarrhea and anorexia
• Chronic- more common problem, from chronic inflammatory reaction to egg passage through intestine/bladder wall, and eggs trapped in other organs
• Immunopathologic reaction
• Hoeppli phenomenon- Ag/Ab reaction to miracidial seretions through egg, resulting in egg granuloma formation in liver, intestinal wall, lungs
• granulomas around eggs coalesce into pseudotubercles
• Concomitant immunity, Antigenic masking- adults long lived, incorporate host antigens onto surface to mask themselves, protect themselves but stimulate immunity against new incoming cercariae

Schistosomes (part 2)

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diagnosis, treatment, control and unique locations

• Dx- history, clinical signs, finding eggs in feces or urine
• fecal, use 0.85% saline (not water), prevent eggs from hatching
• eggs- large, non-operculated, contain a fully formed miracidium, and most have a lateral or terminal spine or small hook
• Tx- Fenbendazole, Praziquantel (better for infection)
• control molluscicidal treatment of waterways, treat infected
• Unique Locations
• Schistosoma nasalis- nasal mucosal veins in cattle, buffalo, horse
• Dendritobilharzia spp.- dorsal aorta of ducks
• duck normal host
• in atypical host, eggs can move to aberrant location with development in carotid arteries or CNS
• causing granulomatous encephalitis with CNS disease

Schistosome dermatitis

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cercarial dermatitis, swimmer's itch, clam-diggers itch

• caused by penetration of human skin by cercariae of avian or mammalian schistosomesc
• causes
• pruritic urticarial sheals then macules, papules and pustules
• acute inflammatory reaction to cercariae, very irritating
• Species incriminated
• Avian schistosomes
• Heterobilharzia americana- raccoons, dogs, and other carnivores

Avian Schistosomes

(six)

"BATDOG"

• Trichobilharzia spp.- ducks, geese
• Gigantobilharzia spp.- gulls, shore birds
• Bilharziella spp.- ducks, herons
• Dendritobilharzia spp.- ducks, swans, geese
• Austrobilharzia spp.- shore birds
• Ornithobilharzia

Alaria spp.

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Trematodes of Digestive System

• small intestine of dog, fox, coyote, cat, mink, raccoon
• Alaria americana, A. marcianae, A. mustelae
• flattened or spoon-shaped forebody w/ suckers; cylindrical hindbody
• Indirect LC
• undeveloped egg develops miracidium> penetrates aquatic snail> cercariae penetrae tadpoles (2nd IH)> becomes mesocercariae> survive metamorphosis to frog> various PH ingest frog> ingestion by carnivore> penetrate intestine> migrate in peritoneal cavity> penetrate diaphragm> enter lungs> tracheal migration to intestine
• transient diplostomulum type metacercariae in lungs
• somatic migration w/ transmammary transmission of A. marcianae in lactating cats
• Most common GI fluke of US
• zoonotic to man through frogs legs, snake
• Pulmonary damage- catarrhal enteritis w/ heavy infections in carnivores
• Dx- eggs in feces, large broadly oval or ellipsoidal, yellow-brown, indistinct operculum, undeveloped, with prominent zygote and numerous yolk cells
• Tx- Praziquantel, prevent ingestion of IH or PH

Nanophyetus salmincola

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Trematodes of the Digestive System

• "salmon poisoning fluke" of carnivores- wild canids, dogs, raccoons
• Indirect Life Cycle
• eggs embryonate slowly (3+ mo)> aquatic snails> cercariae produced> 2nd IH various fish (salmonids, cyprinids)> pacific giant salamanders> metacercariae in muscles, kidneys (can live for years)> ingested deep penetration in small intestine
• Primarily Pacific NW
• dogs infected by eating fish
• on increase of zoonotic infection
• Fluke transmits two rickettsial diseases in animals
• Neorickettsia helminthoeca- "salmon poisoning" of canids, cats not susceptible
• primarily in lymphoid tissues; electrolyte imbalances, vomiting, hemorrhagic enteritis w/ bloody diarrhea, mortality 50-90%
• Neorickettsia elokominica- "Elokomin fluke fever" of canids, bears, raccoons, ferrets
• broader host range, longer incubation, fever persists longer, lower mortality (<10%), less severe, generalized lymphandenopathy and weight loss
• Dx- history, clinical signs important
• eggs- broadly ovoid, light yellow-brown, indistinct operculum, small blunt point or thickened abopercular area of shell, undeveloped
• Rickettsiae in lymph node aspirates
• Tx- more important for rickettsiae, tetracyclines, doxycycline, sulfonamides, penicillini
• treat flukes, Praziquantel
• prevent ingestion of uncooked fish by dogs, freeze fish
• induce vomiting within 3 hours of fish ingestion

Eurytrema sp

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Pancreatic and Liver Flukes of Carnivores

• Eurytrema procyonis
• Pancreatic ducts, occassionally bile ducts of raccoons, cats, foxes, small lanceolate fluke
• Indirect Life Cycle
• embryonated eggs shed> 1st IH terrestrial snail> 2nd IH grasshopper or other arthropod
• Location
• midwest, northeast, southern US
• Heavy infections- thick, cord-like pancreatic ducts, periductal fibrosis, pancreatic atrophy and fibrosis, decreased exocrine function, weight loss, vomiting
• Dx- eggs in feces, oval, yellow-brown
• Tx- Fenbendazole, Praziquantel

Platynosomum sp.

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Pancreatic and Liver Flukes of Carnivores

• "lizard poisoning fluke" of cats
• Adults
• small flukes in bile ducts, gall bladder, ocassionally pancreatic ducts of cats
• Indirect Life Cycle
• embryonated eggs shed> 1st IH terrestrial snail> 2nd IH various lizards and toads (metacercariae)> ingestion of lizards> migration to lizards
• Location
• southern US, caribbean, Hawaii
• Mild infection- ild anorexia, lethargy, decreased condition
• Heavy infection- "lizard poisoning", anorexia, persistent vomiting, diarrhea, icterus, death
• Dx- eggs in feces, gross lesions, clinical signs
• eggs oval, light brown, embryonated
• Tx- Praziquantel, Nitroscanate, Albendazole- surgical removal
• prevent lizard ingestion by cats

Dicrocoelium sp.

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GI and Liver Flukes of Ruminants

• Dicrocoelium dendriticum
• "lancet fluke" of sheep, goats, deer, cattle, rabbits, woodchucks, man (located in bile ducts)
• Adults
• small, lancet shaped, translucent, eggs fairly resistant
• Indirect Life Cycle
• embryonated eggs shed> 1st IH terrestrial snail> sheds cercariae in mucus slime balls (200-400 cercariae)> eatten by various ants 2nd IH> metacercariae in abdomen, occasionally head> infected ants (CNS) exhibit negative geotropism> attach to herbage> infected ants eaten w/ forage> flukes move to bile ducts
• adults life for about 6+ years
• Pathologic changes are slow and progressive
• distended bile ducts, progressive marked cirrhosis and scarring of liver
• few clinical signs, important in older sheep with heavy infections
• manifests as production problem in ewe flock
• produces poor doing sheep, liver condemnation at slaughter
• Dx- eggs in feces, lesions in adult at necropsy
• eggs, small, brown, thick-shelled, lopsided, indistinct operculum, embryonated
• Tx- Albendazole, Fenbendazole Praziquantel, prevention/control via anthelmintics, pasture management, eggs survive for months in pasture

Fasciola hepatica

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GI and Liver Flukes of Ruminants

• Fasciola hepatica- small ruminants, cattle, wild ruminants, rabbits, rodents, man
• F. gigantica- small ruminants, cattle buffalo
• "common liver flukes" of ruminants in bile ducts
• Adults
• large, thin, leaf-like w/ prominent anterior cone and shoulders, highly branched internal organs
• Indirect Life Cycle
• underdeveloped eggs shed> aquatic snails 1st IH> cercariae encyst as metacercariae on water plants, moist vegetation> ingestion> maritas penetrate to abdominal cavity> penetration of liver capsule> migration to liver parenchyma> enter bile ducts and mature
• Location
• poorly drained, wet pastures, marshy areas, ponds, streams, drainage ditches
• snail ecology important
• high biotics, aestivation during hot, dry periods, overwintering
• metacercarial survival, very resistant to drying
• Clinical Syndroms based on intensity- chronic infections more common than acute "liver rot"
• Dx- eggs in feces, signs, lesions/worms at necropsy
• eggs large, broadly ovoid, golden brown, indistinct operculum, unembryonated
• egg passage variable, negative during acute fascioliasis
• Tx- Albendazole: sheep, Clorsulon: cattle , snail control, pasture management

Fascioloides magna

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GI and Liver Flukes of Ruminants

• "giant deer flukes", "giant liver fluke", in deer, moose, elk, cattle, bison, sheep, goats, llamas, pigs
• Adults
• large, oval thick-bodied without prominent anterior cone, except slight cone apperance in contracted young flukes
• Indirect Life Cycle
• similar to Fasciola spp.
• Normal hosts cervids, especially white tailed deer
• Different behavior and pathology in different hosts- deer and elk(normal host)
• liver migration, then matures in thin-walled fibrous systs in liver parenchyma connected with bile ducts
• Bovidae (cattle, bison) and swine
• liver migration, then encapsulation in thick-walled, closed cyst
• thick-walled, black cysts w/ flukes, black pigment and eggs, black migration tracks, hepatic necrosis, inflammation
• black pigment in omentum, low pathogenicity, liver condemnation at slaughter
• Sheep and Goats
• extensive, uninterrupted hepatic migration w/out encapsulation, usually fatal
• extensive traumatic hepatitis w/ hemorrhage, necrosis
• Dx- eggs in feces, worms in liver
• eggs, broadly ovoid, golden brown, with small abopercular projection
• domestic ruminants- history, gross lesions, flukes in liver, no eggs shed in feces
• Tx- Albendazole, don't graze domestic ruminants on deer- contaminated pastures, snail control, don't mix species

• primarily young sheep with heavy infections
• traumatic hepatitis due to migration of large numbers of immatures, often fatal
• swollen, friable liver w/ numerous hemorrhagic migration tracks
• Clinical signs
• sudden lethargy, anorexia, distended, painful abdomen, painful liver palpation, sudden death as early as 6 wks post infection

Black Disease

• seen with fascioliasis
• commonly associated w/ acute/subacute fascioliasis and other traumatic conditions- usually in sheep
• Clostridium novyi
• type B proliferation in liver, activated by fluke trauma, toxin produced
• usually seen in 1-4 year old sheep
• rapidly fatal

Chronic Fascioliasis

• sheep, cattle, higher mortality is sheep
• hepatic fibrosis and cirrhosis due to flukes in bile ducts
• hyperplastic cholangitis; with enlarged, extensive thickening and fibrosis of bile ducts, erosion of epithelium
• Cattle- thick, fibrotic bile ducts, often calcified; "pipe-stem" liver
• anemia, hypoalbuminemia, hypoproteinemia, bottle jaw
• Sheep- progessive weakness, decrease in condition, debility and emaciation due to hepatic damage
• Cattle- emaciation, loss of condition, dec milk production, less mortality, liver condemnations at slaughter

Black-spot disease of fish

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• superficial metacercarial disease on skin, fins, cornea, subQ
• "black spots" or "black grubs"= pigmented metacercarial cysts
• Adults parasites of piscivorous birds and mammals
• Uvulifer ambloplitis- intestine of kingfishers
• Crassiphiala bulboglossa- intestine of kingfishers
• Posthodiplostomum cuticula- intestine of herons and kingfishers
• Minimal pathogenicity in fish, except heavy infections in fry which can be fatal

Monogeneans

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Trematodes and Monogeneans of Fish

• ectoparasites of skin and gills of fish, known to be closely related to tapeworms
• Adults
• D-V flattened, large posterior opisthaptor w/ hooks, suckers, clamps, anchors, anterior mouth and prohaptor
• Life Cycle direct via oncomiracidium larva or viviparity
• Subclass Polyonchoinea- reduced oral sucker, lobed anterior, large opisthaptor w/ large disc, up to 16 hooklets
• Subclass Oligonchoinea- mouth surrounded by prohaptor, opisthaptor w/ suckers and clamps, +/- hooklets
• Tx- control, avoid introduction of infected fish, quarantine
• dilute formaldehyde, organophosphates in water

Taenia saginata

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Cestodes

• "beef tapeworm" of man, zoonotic from cattle
• adult
• large, unarmed scolex, life span to 25 years
• gravid proglottids, 3-10 segments shed/day
• cattle primary IH, cysticerus larvae in skeletal and cardiac muscles
• Common in beef eaters- raw or improperly cooked beef
• Bovine cysticercosis- larval infection
• Infection
• adults are well tolerated in humans, eosinophilia, IgE, rectal irritation
• well tolerated in cattle except for heavy infection
• Dx- Man: proglottids and eggs in feces, meat inspection
• Tx- sanitation, cook, freezing meat properly

Bovine Cysticercosis

• "measly beef", "beef measles"
• epidemiology
• human feces/sewage contamination to cattle, sewage effluents, flooding, sludge usage
• eggs survive sewage treatment and on pasture for up to 8 wks
• important cause of carcass condemnation and downgrading

Taenia solium

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Cestodes

• "pork tapeworm" and cysticercosis of man, zoonotic from swine
• Adult
• armed scolex, cysticerci in swine IH and man (both infective to humans)
• Location
• common in Latin America, Africa, India, associated with poor sanitation
• Human cysticercosis a major problem in Latin America infected by
• seen in skeletal muscle, commonly in subQ, CNS, ocular, slow development of serious CNS signs and patholgy
• human feces contamination of food/water
• hand to mouth transmission
• intestinal autoinfection
• Dx- Man: proglottids, eggs, radiology, CT, MRI, ELISA
• Meat inspection for swine
• Tx- more careful control because eggs are directally infective to humans

Taenia pisiformis

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Taeniid Tapeworm of Canids and Felids

• dogs, wild canids (very common)
• adults
• rectangular, single lateral genital atria
• Indirect Life Cycle
• IH is rabits (wld cottontail)> liver migration> cysticerci in peritoneum> mesentery, viscera
• causes hepatic migration damage, traumatic hepatitis with heavy infection, perianal irritation in dogs
• Prevent ingestion of rabbit viscera

Taenia hydatigena

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Taeniid Tapeworms of canids and felids

• dog, coyote, wolf
• Indirect LC
• IH sheep, goats, cattle, wild ruminants, pigs> liver migration of oncosphere> enter peritoneal cavity> forms large cysticercus larva in omentum> serosa of viscera
• sporatic problem in sheep and goats, farm dogs fed ovine viscera
• Adults
• non-pathogenic
• Larvae in sheep
• hemorrhagic migration tracks in liver> progress to fibrosis, can precipitate "black disease" Cl. novyi
• tramatic hepatitis in young lambs with heavy infection
• Dx- Taenia type proglottids, eggs
• Tx- dogs: don't feed sheep viscera

Taenia ovis

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Taeniid Tapeworm of Canids and feline

• dogs, wild canids
• Indirect LC
• IH sheep and goat> cysticerci in skeletal and cardiac muscles
• Important cause of carcass and meat condemnation, important in mutton and lamb
• Prevention and control are the same as T. hydatigena

Taenia multiceps

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Taeniid Tapeworms of Canids and Felids

Taenia serialis

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Tapeworm of canids and felids

• DH- fox, coyote
• IH- rabbits, hares, occasionally other spp.
• coenuris larvae are 4cm, usually subQ, intermuscular connective tissue, peritoneal cavity, proliferative, branching
• Dx, Tx- prevention and control
•  same as T. multiceps
• potential zoonosis- eggs directally infective

Taenia crassiceps

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tapeworm of canids and felids

• dogs,and wild canids
• IH rodents- subcutaneous cysticercosis
• small cysticerci can reproduce by exogenous budding
• Potential zoonosis- eggs directly infective, subQ, intraocular

Taenia taeniaeformis

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tapeworm canids and felids

• DH are cats
• IH are rodents, strobilocercus larvae encyst in liver
• strobilocercus larvae encyst in liver- evaginated scolex, pseudostrobilization
• Adult is non-pathogenic- larva can induce hepatic sarcomas
• Dx, Tx- prevention and control are the same as for other Taenia spp.

Echinococcus granulosus

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tapeworm

• "hydatid tapeworm" of dogs, foxes, coyotes, wolves, ect
• Adults are tiny
• life span 5-12 months, non-pathogenic unless severe infection, then mild enteritis
• Eggs
• typical taeniid eggs are shed in feces
• Important zoonosis: eggs are directally infective
• Indirect Life Cycle
• IH are various ungulates, man, other spp> oncosphere to lungs, liver> vesiculates, grows slowly and becomes> hydatid cyst