Parasites of Dogs and Cats: Cestodes

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Cestodes of Dogs and Cats (Exam I)

Characteristics of Cyclophyllidea

-1 intermediate host
- Organs of attachment are scolex and suckers
-Eggs is an oncosphere, nonciliated

Characteristics of Pseudophyllidea

-2 intermediate hosts (1st is a crustacean)
-Organs of attachment are scolex and bothria
-Egg is an oncosphere with cilia for motility

Dipylidium caninum:
Taxonomy

-Order: Cyclophyllidea
-Family: Dilepididae
-Genus species: Diphylidium caninum
-Common Name: Common tapeworm, Cucumber tapeworm, Double pored dog tapeworm, flea tapeworm

Dipylidium caninum:
Hosts

-Final host: Dogs, cats, canids, felids, occasionally humans
-Intermediate hosts: flea and louse
-Zoonosis

Dipylidium caninum:
Identification

-Max length of 50 cm (shorter than Taenia)
-Proglottid easily recognized: elongated like large rice grain when dry and cucumber seeds when fresh
-Each proglottid has 2 sets of reproductive organs with bilateral genital pores
-Single segments pass
-Egg packets: contain 10-20 eggs (each 35-40um)

Dipylidium caninum:
Life Cycle

-Indirect
--Newly passed segments are active and can crawl around perianal region
-Oncospheres contained in egg packets are expelled by an active segment or released by active disintegration
-Ingested by IH (only larval stage of fleas, any stage of louse) and travels to abdominal cavity where it develops into cysticercoids
-Final host ingests IH containing cysticercoids

Dipylidium caninum:
PPP

-21 days
-Development in louse is 30 days
-Development in the flea takes several months

Dipylidium caninum:
Sites of Infection

-Adult in small intestine
-Larvae (cysticercoid) in the flea and louse in abdominal cavity

Dipylidium caninum:
Pathogenesis and Lesions

Adults are non-pathogenic, may cause discomfort

Dipylidium caninum:
Clinical Signs

-Excessive grooming of the perineum
-Scooting or rub anus along the floor

Dipylidium caninum:
Diagnosis

-Presence of segment on the coat around perineum
-Dry rice grain in dog bedding
-Segments are elongated and the double gential organs are visible with a hands lens
-Scotch tape test

Dipylidium caninum:
Treatment and Prevention

-Cestocide
-Flea control is important, treat environment with insecticide

Echinococcus granulosus:
Taxonomy

-Order: Cyclophyllidea
-Family: Taeniidae
-Genus species: Echinococcus granulosus
-Common Name: Hydatid tapeworm

Echinococcus granulosus:
Hosts

-Final host: dogs and canids
-Intermediate hosts: herbivores (wild and domestic)
-Zoonosis: humans

Echinoccus granulosus:
Adult Identification

-6mm with 3-4 segments
-Scolex with 4 suckers and 2 rows of hooks
-Small, so difficult to see in open intestine

Echinoccus granulosus:
Hydatid Cyst Identification

-In IH contains brood capsule and scolices
-Fluid filled cyst
-Usually 5-10cm, but up to 50cm in diameter
-Endogenous budding of multiple brood capsules, each containing many scolices
-When capsule ruptures it released "hydatid sand" in the hydatid fluid

Echinoccus granulosus:
Egg Identification

-25-40um
-Brown color
-Radial striations
-6 embryonic hooks (hexacanth)
-Indistinguishable from Taenia spp.

Echinococcus granulosus:
Life Cycle

-Indirect
-Adults shed 1 gravid segments with eggs in the feces, which are viable on the ground for 2 years
-Eggs ingested by IH, hatches into hexacanth larvae
-Larvae penetrates the intestines and migrate to the liver and lungs
-Hydatid develops (infective stage), it is slow growing and matures in 6-12 months
-FH ingests IH, the scolices evaginate and attach to the mucosa of the small intestine and mature

Echinococcus granulosus:
PPP

45-60 days

Echinococcus granulosus:
Sites of Infection

-Adults in small intestine
-In IH and humans, the unilocular hydtaid cysts are in the liver, lungs and other organs

Echinococcus granulosus:
Pathogenesis and Lesions

-Adults are non-pathogenic in the final host
-In IH the hydatid develops in a pulmonary or hepatic site, which often causes pathogenesis

Echinococcus granulosus:
Clinical Signs

-No signs in final host
-Humans: if 1 or both lungs are affected results in respiratory symptoms, if several hydatids are present in liver results in abdominal distention

Echinococcus granulosus:
Diagnosis

-Eggs in feces using fecal flotation
-Eggs are indistinguishable from Taenia spp.
-Scotch tape test

Echinococcus granulosus:
Treatment and Prevention

-Anthelmintic treatment for dogs
-Removal of stray dogs
-Prohibition against feeding uncooked offal to dogs or other canids

Echinococcus multilocularis:
Taxonomy

-Order: Cyclophyllidea
-Family: Taeniidae
-Genus species: Echinococcus multilocularis
-Common Name: Alveolar Hydatid Cyst

Echinococcus multilocularis:
Hosts

-Final hosts: Dogs, wild canids, cats and coyotes
-Intermediate hosts: Cattle, equids, swine and rodents
-Zoonosis: humans

Echinococcus multilocularis:
Adult Identification

-6mm long with 4-5 segments
-Small, so difficult to see in small intestine
-Scolex with 4 suckers and 2 rows of hooks
-Similar to E. granulosus

Echinococcus multilocularis:
Alveolar Hydatid Cysts Identification

-Occur in the liver and other organs of IH
-Not confined to a capsule and has exogenous budding, which infiltrates the surrounding tissue
-Diffuse growth with compartments filled with gelatinous matrix and many brood capsules
-As hydatid grows the centre dies and is filled with necrotic tissue

Echinococcus multilocularis:
Egg Identification

-25-40um brown color
-Radial striations in the shell
-Hexacanth
-Indistinguishable from Taenia spp.
-Not easily seen on fecal flotation, because they leave host in segments

Echinococcus multilocularis:
Life Cycle

-Indirect
-Gravid segments are shed, disintegrate into liberate eggs whicha re passed in feces
-IH ingests eggs, hatches and larva penetrates intestine and migrates to the liver and less commonly the lungs and brain
-Larva develops into alveolar hydatid cyst (infective stage), it is slow growing invasive and extends locally and capable of systemic metastases to various organs
-Many compartments contain gelatinous matrix into which scolices bud off
-FH ingests IH, the scolices evaginate and attach to the mucosa of the small insteine amd mature

Echinococcus multilocularis:
PPP

28 days

Echinococcus multilocularis:
Sites of Infection

-Adults in small intestine
-Multilocular hydatid cysts in liver, with metastases to other organs

Echinococcus multilocularis:
Pathogenesis and Lesions

-Final host: non-pathogenic
-IH: develops an alveolar or multilocular cyst in liver, which grows large and becomes space occupying lesion causing pressure necrosis of surrounding tissue

Echinococcus multilocularis:
Clinical Signs

-Rare in final host despite large numbers of adults
-Invasive growth of hydatid cyst in humans can be fatal

Echinococcus multilocularis:
Diagnosis

-Eggs in fecal flotation
-Eggs indistinguishable from Taenia spp.
-Scotch tape test

Echinococcus multilocularis:
Treatment and Prevention

-Anthelmintic
-Removal of stray dogs
-Prohibition against feeding uncooked offal

Taenia crassiceps:
Taxonomy

-Order: Cyclophyllidea
-Family: Taeniidae
-Genus species: Taenia crassiceps

Taenia crassiceps:
Hosts

-Final Host: Foxes and dogs
-Intermediate Hosts: Small rodents
-Zoonosis: Humans

Taenia crassiceps:
Adult Identification

-Up to 2m long
-Scolex and 4 suckers
-Segments are rectangular with unilateral genital pores irregularly alternating from one side to the other

Taenia crassiceps:
Larva Identification

-Cysticerci in abdominal cavity in IH
-Asexual budding results in many cysterci surrounded by a single host tissue capsule

Taenia crassiceps:
Egg Identification

-Brown color
-Radial striations
-Hexacanth
-Indistinguishable from Echinococcus spp.
-Not easily seen on fecal flotation, because they leave the host in segments

Taenia crassiceps:
Life Cycle

-Gravid segments are shed in feces, which release eggs to the environment and develop into oncospheres
-Oncosphere is ingested by IH, enters the body wall of the small intestine and migrations to the abdominal cavity
-Develops to cysticerci (infective stage), asexual budding results in many cysticerci surrounded by a single host tissue capsule
-Final host ingests IH, it is digested and develop in the small intestine to an adult

Taenia crassiceps:
PPP

6-9 weeks

Taenia crassiceps:
Sites of Infection

-Adult in small intestine
-Larvae in abdominal cavity of IH

Taenia crassiceps:
Pathogenesis and Lesions

-Infections in humans are potentially serious because of proliferative nature of cysticerci
-Can infect the eye, leading to blindness
-Immunocompromised may develop proliferative cysticercosis

Taenia crassiceps:
Clinical Signs

Asymptomatic in final host

Taenia crassiceps:
Diagnosis

-Eggs in fecal flotation
-Indistinguishable from Echinococcus spp.

Taenia crassiceps:
Treatment and Prevention

-Cesocidal drugs
-Prevention of offal from infected IH given to final host

Taenia pisisformis:
Taxonomy

-Order: Cyclophyllidea
-Family: Taeniidae
-Genus species: Taenia pisiformis

Taenia pisiformis:
Hosts

-Final Hosts: Dogs, foxes and wolves
-Intermediate Hosts: Rabbits

Taenia pisiformis:
Identification

-Adult: several meters
-Cysticerci in IH

Taenia pisiformis:
Life Cycle

-Gravid segments are shed in feces, which release eggs to the environment and develop into oncospheres
-Oncosphere is ingested by IH, enters the body wall of the small intestine and migrations to the liver and peritoneum
-Develops to cysticerci (infective stage)
-Final host ingests IH, it is digested and develop in small intestine to adult

Taenia pisiformis:
Sites of Infection

-Adults in small intestine of FH
-Cysticercus in liver and peritoneum of IH

Taenia pisiformis:
Pathogenesis and Lesions

Non-pathogenic in final host

Taenia pisiformis:
Clinical Signs

Asymptomatic

Taenia pisiformis:
Diagnosis

-Eggs in fecal flotation
-Indistinguishable from Echinococcus spp.

Taenia pisiformis:
Treatment and Prevention

-Cestocidal drugs
-Prevention of feeding infective offal to final host

Taenia taeniaeformis:
Taxonomy

-Order: Cyclophyllidea
-Family: Taeniidae
-Genus species: Taenia taeniaeformis

Taenia taeniaeformis:
Hosts

-Final Hosts: Cats
-Intermediate Hosts: Mice and rats
-Zoonosis: Rarely humans

Taenia taeniaeformis:
Identification

-Adult: up to 60cm in FH
-Strobilocercus in liver of IH
-Eggs: 25-40um

Taenia taeniaeformis:
Life Cycle

-Gravid segments are shed in feces, which release eggs to the environment and develop into oncospheres
-Oncosphere is ingested by IH, enters the body wall of the small intestine and migrations to the liver and peritoneum
-Develops to strobilocercus (infective stage)
-Final host ingests IH, it is digested and develop in
small intestine to adult

Taenia taeniaeformis:
Pathogenesis and Lesions

Non-pathogenic to final host

Taenia taeniaeformis:
Clinical Signs

Asymptomatic

Taenia taeniaeformis:
Diagnosis

-Eggs in fecal flotation
-Indistinguishable from Echinococcus spp.

Taenia taeniaeformis:
Treatment and Prevention

-Cestocidal drugs
-Prevention of feeding infected offal to final hosts

Diphyllobotrium latum:
Taxonomy

-Order: Pseudophyllidea
-Family: Diphyllobothriidae
-Species genus: Diphyllobotrium latum
-Common Name: Broad fish tapeworm

Diphyllobotrium latum:
Hosts

-Final Hosts: Humans and fish eating mammals (dogs, cats, pigs, seals and bears)
-Intermediate Hosts (2): First is a copecod crustacean, Second is a freshwater fish
-Paratenic Hosts: Other fish
-Zoonosis

Diphyllobotrium latum:
Identification

-Adults: 12m long in small intestine, scolex with bothria, square sgments shed in groups
-Eggs: operculate, light brown, 60um

Diphyllobotrium latum:
Life Cycle

-Eggs passed from genital pores of gravid segments (which remain in chains) in feces
-Eggs develop in water, hatch to cilited coracidium -Eggs ingested by copecod crustacean and develops to procercoid
-Freshwater fish ingest crustacean and it develops to procercoid, which migrates to the muscles and viscera
-Final host ingests freshwater fish or PH and it develop to adult

Diphyllobotrium latum:
PPP

5-6 weeks

Diphyllobotrium latum:
Sites of Infection

-Adults in small intestine
-Proceroid in copecod crustacean
-Pleroceroid in muscles and viscera of fish

Diphyllobotrium latum:
Pathogenesis and Lesions

-Adults may be very pathogenic
-In humans causes marcocytic anemia (larger RBC and increased hemoglobin) due to its uptake of vitamin B12

Diphyllobotrium latum:
Diagnosis

-Fecal sedimentation exam reveals numerous eggs
-Eggs: yellow operculate (resembles Fasciola hepatica except half the size)

Diphyllobotrium latum:
Treatment and Prevention

-Cestocidal drugs
-Where common, prevent feeding undercooked freshwater fish to final hosts

Spirometra spp:
Taxonomy

-Order: Pseudophyllidea
-Family: Diphyllobothriidae
-Species genus: Spirometra spp
-Common Name: Zipperworm

Spirometra spp:
Hosts

-Final Hosts: Bobcats, dogs, cats, lynxes and raccoons
-Intermediate Hosts: First is a crustacean, Second are water snakes, frogs, rodents, birds (any vertebrae except fish)
-Zoonosis: Sparaganosis in humans

Spirometra spp:
Identification

-Adults: 2m in length, scolex with bothria, segments shed in groups, reproductive organs in center of segments
-Plerocercoids: 4-10cm length in humans
-Eggs: Operculate eggs discharged through uterine pores, light brown color, 60um

Spirometra spp:
Life Cycle

-Eggs passed from genital pores of gravid segments (remain attached in chains) in feces
-Eggs develop in water and hatch to ciliated corcidium
-Ingested by crustacean and develops to procercoid
-Crustacean is ingested by second IH and develops to perocercoid
-Final host ingests second IH and develops to adult

Spirometra spp:
PPP

2-4 weeks

Spirometra spp:
Sites of Infection

-Adults in small intestine
-Larval stage are procercoid and plerocercoid

Spirometra spp:
Pathogenesis and Lesions

-Asymptomatic in final hosts
-Plerocercoids capable of causing human sparganosis
-Most common transfer of plerocercoids is that of the poultice of freshly caught frog or water snake applied to wounds or black eye
-Plerocercoids can also be ingested from an infected frog, snake
-Humans drink contaminated water that contains procercoids within the copecod
-In all modes the plerocercoids or procercoids migrate around the subcutaneous connective tissue

Spirometra spp:
Diagnosis

-Fecal sedimentation reveal numerous eggs
-Eggs: yellow and operculate (resembles Fasciola hepatica, but half the size)

Spirometra spp:
Treatment and Prevention

-Cestocidal drugs
-In common areas, don't feed product from IH unless thoroughly cooked

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