CP Exam 3 Notes 2 PDF

CLINICAL PATHOLOGY I – Lecture Cestodes: The Tapeworms Kingdom: Animalia Phylum: Platyhelmiths Class: Cestode Subclass: Eucestoda=true tapeworm Order: Cyclophyllidean Subclass: Cotyloda=psuedotapeworms Order: Diphyllobothriidean I. Overview...

CLINICAL PATHOLOGY I – Lecture Cestodes: The Tapeworms Kingdom: Animalia Phylum: Platyhelmiths Class: Cestode Subclass: Eucestoda=true tapeworm Order: Cyclophyllidean Subclass: Cotyloda=psuedotapeworms Order: Diphyllobothriidean I. Overview of Cestodes Flatworms that lack a body cavity Always indirect life cycle A. Cyclophyllidean: “True” tapeworms; scolex contains suckers, and may be “armed” (contain hooklets) or “unarmed” (no hooklets); genital pores are laterally located on the proglottid; require one IH. ** =Zoonotic 1. Dipylidium caninum** 2. Taenia spp. T. pisiformis (dogs and other canids) T. hydatigena (dogs and other canids) T. ovis (dogs and other canids) T. taeniaeformis (cats and other felids) 3. Echinococcus spp.** E. granulosis (dogs and other canids) E. multilocularis (dogs, cats, wild canids and felids) B. Cotyloda :“Pseudo tapeworms”; scolex contains two bothria (slit-like organs of attachment); genital pores are centrally located on proglottid; require two IHs. ** =Zoonotic 1. Diphyllobothrium latum** 2. Spirometra spp.** II. Cestode Life Cycle and Anatomy A. Cestode Life Cycle 1. Indirect = Requires IH 2. Adults attached by scolex to mucosa of small intestine 3. Proglottids containing ova infective to IH pass in feces; ova are infective to IH upon passage. 4. Ova ingested by and mature in IH 5. IH must be eaten by DH to complete life cycle – oral transmission only B. Adult Cestode  1. In small intestine 2. Contains NO digestive organs -- absorbs food/nutrients through specialized tegument 3. Extremely variable in size: From Diphyllobothrium latum (30 ft) to Echinococcus granulosis (6 mm) C. Cestode Anatomy 1. Scolex = “Head” “Holdfast” Attaches to intestinal wall via hooks and/or suckers Located at anterior end of organism 2. Proglottids = “Segments” Flattened Absorb nutrients from bowel of DH Separate from strobila when mature and pass intermittently Hermaphroditic : Contain both male and female reproductive organs Most distal segments are more mature and gravid Very commonly seen by clients D. Ova 1. Contained within proglottids that pass with feces 2. Contain 1 stage larva (oncosphere or hexacanth embryo) infective to IH upon passage (this is st different in pseudotapeworms) 3. Ingested by IH E. Larvae st 1. 1 Stage Larva Infective immediately upon passage to IH Oncosphere is 1 stage larva which develops to 2 st nd stage larva in body cavities or tissues of IH nd 2. 2 Stage Larva Infective to DH Cysticercus or cysticercoid: Refers to 2 stage larva nd ▪ Cysticercus in mammalian IH; e.g., Taenia and Echinococcus ▪ Cysticercoid in arthropod IH; e.g., Dipylidium Clear, fluid-filled sac (containing scolex) is infective to DH  Commonly known as “bladderworm” 3. “Bladderworm” Develops in IH likely to be eaten by DH Once ingested, “bladder” digested away and scolex imbeds in mucosa of DH's small intestine III. Cyclophyllidean: “True” tapeworms A. Dipylidium caninum: The “flea tapeworm” 1. Adults in small intestine of DH mature and release gravid proglottids 2. Ovum of tapeworm ingested by larval flea (Ctenocephalides spp.) or biting louse which serve as IH 3. Cysticercoid forms in flea (or louse) 4. Dog or cat ingests flea (or louse) while grooming 5. Prepatent period = 4 weeks 6. Dx: “Cucumber seed” segments on perineal area 7. Proglottids have double pores at lateral midpoint 8. Ova frequently remain inside segments and are not easily found 9. Tx: Must tx for fleas at same time as treating for tapeworms 10. ZOONOTIC if human ingests infested flea B. Taenia spp. 1. Adult segments are rectangular and ~ size of rice 2. Proglottids have single pore at lateral midpoint 3. Ova are passed in proglottids 4. Ova are emptied from proglottid as it moves about on fecal mass C. Taenia pisiformis 1. Adults in small intestine of dog (DH) mature and release gravid proglottids 2. Proglottids release eggs eaten by grazing rabbit (IH)  3. Cysticercus (“bladderworm”) develops in rabbit’s tissues 4. Dog eats raw or undercooked rabbit and becomes infested 5. Prepatent period = 8 weeks D. Taenia hydatigena and Taenia ovis 1. Infective ova pass in feces of canine DH 2. Ova ingested by appropriate IH T. hydatigena: Sheep T. ovis: Sheep 3. DH consumes raw tissue of infested IH 4. Life cycle completed in DH 5. Prepatent period ~ 8 weeks E. Taenia taeniaeformis 1. Similar to T. pisiformis, etc. except involves cats (DH) and mice (IH) 2. VERY common in cats allowed to hunt 3. Recurrent infestations are typical 4. Prepatent period = 4 to 6 weeks F. Echinococcus spp. (ZOONOTIC and REPORTABLE) 1. Adults are tiny, 1.2 - 7 mm in length Composed of scolex and three proglottids Proglottids: #1 immature, #2 mature, and #3 is gravid 2. 1 st nd stage larva develops into hydatid cyst (2 stage larva) in IH's bocy. [Hydatid cyst is analogous to“bladderworm”] G. Echinococcus granulosis 1. Adults in small intestine of dog (and other wild canids); do not cause significant disease in DH 2. Proglottid passed and oncosphere ingested by IH a. Typically sheep or other ruminants; sometimes swine, horses, and even kangaroosAnd sometimes by people. 3. ZOONOTIC 4. Prepatent period = 4 to 8 weeks 5. Larvae form hydatid cysts in various tissues of IH ▪ Liver  ▪ Lungs ▪ Kidneys ▪ Spleen ▪ Bone ▪ Brain 6. Disease is “hydatidosis” 7. In people, cysts can be very large (grapefruit-sized) and cause terrible disease due to space- occupying properties 8. Life cycle complete when IH is consumed by DH; i.e., sheep eaten by dog H. Echinococcus multilocularis 1. Adults in small intestine of dogs, foxes, coyotes, wolves, and cats; do not cause significant disease in DH 2. Life cycle same as E. granulosis except IHs are mice and occasionally people 3. ZOONOTIC 4. Prepatent period = 4 to 8 weeks 5. “Alveolar hydatidosis” 6. Larvae produce alveolar hydatid cysts that continuously grow and infiltrate tissues of the liver, lung, brain, kidney, spleen, bone and other organs (like malignant neoplasm) 7. Alveolar hydatid infestations typically prove fatal in few years I. Echinococcus spp. other information 1. Diagnosis Cannot differentiate ova from Taenia spp. -- must identify adult worms May collect adults via purgative 2. Wildlife & Echinococcus spp. Sylvatic cycles exist with moose/wolves/sled dogs/people Dogs infested by scavenging wild game, shed infective oncospheres in their feces People infested via poor hygiene after handling dog feces – WASH YOUR HANDS 3. Public Health Concerns of Echinococcus spp. Humans can serve as IH Hydatid cysts are space-occupying lesions which can be fatal to people Do not feed raw meat to pets Do not let cats or dogs hunt IV. Cotyloda “Pseudotapeworms” A. Diphyllobothrium latum**  1. Zoonotic potential 2. Requires two IHs st 1 is copepod (small crustaceans found in saltwater and freshwater) nd 2 is fish 3. DH (dogs, cats and humans) infested via raw fish 4. Prepatent period ~ 6 weeks 5. Dx Identification of characteristic operculated egg Identification of proglottid via medial pore B. Spirometra spp.** 1. Zoonotic potential 2. Requires two IHs st 1 is copepod nd 2 varies; i.e., amphibian, reptile, bird, mammal including humans nd 3. DH (dogs and cats) infested via ingestion 2 IH 4. Prepatent period 2 to 4 weeks 5. Mature proglottids separate along longitudinal axis, hence name “zipper” tapeworm 6. Dx o Large operculated ovum o Proglottids have medial pore V. Signs and symptoms, diagnosis, and treatment of Cestodes A. Clinical Sign of Cestodes 1. Owners often observe proglottids around rectum and/or on bedding 2. Signs usually minimal ▪ Occasional “scooting” ▪ Licking anal area ▪ Unthriftiness ▪ Mild diarrhea B. Ovum Identification 1. Can differentiate Dipylidium ova from Taenia/Echinococcus 2. Cannot differentiate Taenia ova from Echinococcus ova 3. Diphyllobothrium latum and Spirometra spp. easily differentiated from cyclophyllideans C. Proglottid Identification 1. May need to rehydrate to examine 2. What’s the procedure for doing this? 3. What are we looking to find? D. Cestode Tx 1. Requires very specific meds Praziquantel Epsiprantel  2. NOT Ivermectin Fenbendazole (although this drug will eliminate most species of Taenia) E. Economic Importance Cysticerci or hydatid cysts in sheep and cattle will cause lesions (often in liver – hepatic lesions), meat inspectors will condemn entire carcass F. Prevention of Cestodes in Pets 1. Eliminate fleas 2. Don’t permit pets to hunt 3. Don’t feed raw meat to pets 4. Don’t feed raw fish to pets G. Prevention of Zoonotic Cestodes in Humans 1. Don’t eat fleas 2. Don’t permit pets to hunt 3. Don’t feed raw meat to pets 4. Don’t eat raw fish 5. Wash your hands Cestode Terminology 1. Scolex: Aka “holdfast”; the attachment end of a tapeworm, considered to be the anterior end. 2. Strobila: The chain of proglottids that make up the bulk of the body of a tapeworm. 3. Proglottid: One of the segments that comprise the strobila. 4. Oncosphere: Aka “hexacanth embryo”; the first stage larva containing 6 hooklets that is infective to the IH; can be spelled “onchosphere”. 5. Hexacanth embryo: Aka “oncosphere” (see above). 6. Cysticercus: The cyst-like larval stage of cestodes that form in the tissues of the mammalian IH; this stage is infective to the DH; commonly referred to as a “bladderworm”’; plural is “cysticerci”. 7. Cysticercoid: The cyst-like larval stage of cestodes that form in an arthropod IH. 8. Hydatid cyst: The cyst-like larval stage of Echinococcus granulosis that forms in the tissues of the IH; this stage is infective to the DH. (This is analogous to the cysticercus of Taenia spp.) 9. Alveolar hydatid cyst: Cyst-like larval stage of Echinococcus multilocularis that forms in the tissues of the IH; named “alveolar” due to its form of asexual reproduction within the IH. 10. Hydatidosis: Disease caused by the presence of hydatid cysts. 11. Gravid: Pregnant; containing developing young. 12. Sylvatic: Involving animals of the forest; found in the woods. 13. Cyclophyllidean: “True” tapeworms; scolex bears suckers, and may be “armed” (contain hooklets) or “unarmed” (no hooklets); genital pores are laterally located on the proglottid; require one IH. 14. Cotyloda “Pseudo tapeworms”; scolex bears two bothria (slit-like organs of attachment); genital pores are centrally located on proglottid; require two IHs. Quick look at DH and IH 1. Dipylidium caninum** o DH includes dog, cat and human o IH is flea; occasionally dog louse 2. Taenia pisiformis o DH is dog (can be found in other canids) o IH is wild lagomorph 3. Taenia hydatigena o DH is dog (can be found in other canids) o IH is sheep 4. Taenia ovis o DH is dog (can be found in other canids) o IH is sheep 5. Taenia taeniaeformis o DH is cat (can be found in other felids) o His include mice and rats 6. Echinococcus granulosis** o DH is dog (and other wild canids) o IH are ruminants (sheep, cattle, moose, caribou and others) and humans 7. Echinococcus multilocularis**  o DH are dogs and cats o IHs are rodents and humans 8. Diphyllobothrium latum** o DH are dogs, cats, and humans o IHs Copepod Fish 9. Spirometra spp.** o DH are dogs and cats o IHs Copepod Amphibians, reptiles, birds, various mammals including humans 1 10/2/2021  CLINICAL PATHOLOGY – Lecture Large Animal Cestodes I. Equine Cestodes A. Genus and species 1. Anoplocephala perfoliata: Junction of ileum and cecum and in large intestine 2. Anoplocephala magna: Small intestine 3. Paranoplocephala mamillana: Small intestine (and sometimes the stomach) B. Life Cycle of Equine Cestodes 1. Indirect life cycle: 2. Adults live in bowel (sometimes stomach) and develop gravid proglottids that pass in manure 3. Proglottids dry out, burst open, ova are eaten by free-living, ubiquitous oribatid mites 4. IH =Oribatid mites: Free-living inhabitants of humus (organic portion of soil) 5. Life cycle completed when horse ingests mite while grazing 6. Prepatent period = 4 to 6 weeks C. Cestode Clinical Signs 1. Can be nonpathogenic; however... 2. Heavy infestations (especially w/ Anoplocephala perfoliata) can cause Poor growth / failure to thrive Diarrhea Colic Abscess / infection at site of attachment Intussusception Intestinal perforation / peritonitis 3. No age-related immunity to cestodes D. Cestode Diagnosis & Treatment 1. Diagnosis: Discharge of proglottids is sporadic  Segments rarely seen around anus or in manure Eggs difficult to find with sedimentation or flotation techniques Eggs are angular and vary in appearance 2. Treatment Praziquantel Pyrantel pamoate (at double regular dose) II. Ruminant Cestodes A. Genus and species 1. Moniezia spp. 2. Taenia spp.** 3. Echinococcus granulosis** **=NO PATENT INFESTATION – Ruminants serve as IH only. B. Moniezia spp. 1. Life cycle = Indirect 2. DH = Sheep, goats, cattle 3. IH = Oribatid mite 4. Transmission = Ingestion of IH 5. Location in DH = Small intestine 6. Prepatent period = 40 days 7. Proglottids, eggs, mites → DH 8. Generally nonpathogenic: Often subclinical Heavy infestations can cause unthriftiness and may lead to obstruction 9. Diagnosis = Proglottids or eggs in feces 10. Treatment = Fenbendazole C. Taenia spp.-Ruminants serve as the IH for all these parasites – no patent infestations of Taenia spp. in ruminants. 1. Taenia saginata  DH = Humans IH = Cattle Transmission to IH = Fecal-oral (contamination of feed or pastures with human feces) Diagnosis in IH = Cysticercus observed in carcass at slaughter Treatment of IH = Not economically justified Treatment of DH = Praziquantel or fenbendazole Importance = ZOONOTIC and economic loss 2. T. ovis, T. multiceps, and T. hydatigena DH = Dogs and other canids IH = Sheep, goats and occasionally cattle Transmission to IH = Fecal-oral (contamination of feed or pastures with dog feces) Diagnosis in IH = Cysticercus observed in carcass at slaughter Treatment of IH = Not economically justified Treatment of DH = Praziquantel or fenbendazole Prevention = Exclude dogs from pasture and do not feed raw meat Importance = Economic loss D. Echinococcus granulosis Ruminants serve as the IH only “Hydatidosis” or “hydatid cyst disease” in IH DH = Dogs and wild canids. IH = PEOPLE and ruminants (also swine, horses and even kangaroos). Transmission to IH = Fecal-oral. Diagnosis in IH = Hydatid cyst in liver, lung or brain. Treatment of IH = No drug treatment; surgical removal in humans Treatment of DH = Praziquantel.  CLINICAL PATHOLOGY I - Lecture Trematodes o Commonly called “flukes” which is an old English name for “flounder” o Life cycle = Indirect ▪ Asexual reproduction within IH ▪ Sexual reproduction within DH o Location in DH ▪ Intestines ▪ Liver and bile ducts ▪ Lungs ▪ Blood vessels ▪ Other organs Fasciola hepatica=Liver Fluke o “Fascioliosis” o Most important trematode of livestock in the world o Found primarily along Gulf coast and in the Pacific Northwest; also endemic in areas of Rocky Mountain region ▪ Thrives in mild climates with wet / marshy areas ▪ Snail is IH o DH = Ruminants (and other mammals) o Location in DH = Bile ducts of liver o Life cycle = Indirect o IH = Snail o Transmission = Ingestion of infective stage o Diagnosis = Fluke eggs in feces o Prepatent period = 10 to 12 weeks o ZOONOTIC (very rare) = Ingestion of metacercaria via consumption of raw watercress F. hepatica Life Cycle o Adult flukes in bile ducts of liver undergo sexual reproduction to produce ova o Ova travel down bile ducts to gall bladder, are discharged into intestine and then passed in feces o Ova that land in water hatch into larvae o Miracidiae swim in search of specific snail species (Lymnaea truncatula) o Miracidiae burrow into the snail’s body o Asexual reproduction occurs in the IH, producing cercariae o Cercariae exit the snail, swim to a plant, and migrate up plant to just above water level o Cercariae encyst on plants and lose their tails – are now metacercariae o Ruminant ingests metacercariae while grazing o Cyst wall is digested in DH’s small intestine, releasing the marita o Maritas penetrate wall of intestine, cross peritoneal space and enter the liver of DH o Bore around liver for several weeks, finally entering bile ducts to mature into adult flukes  o Adult flukes undergo sexual reproduction to produce ova, and life cycle is complete Three forms of infestation o Chronic ▪ Rarely fatal in cattle ▪ Commonly fatal in sheep o Acute ▪ Occurs primarily in sheep ▪ Typically fatal o “Black Disease” also called Infectious Necrotic Hepatitis ▪ Occurs primarily in sheep ▪ Usually fatal o Chronic fascioliosis = Chronic fibrotic hepatitis ▪ Anemia ▪ Unthriftiness ▪ Submandibular edema; i.e., “bottle jaw” ▪ Reduced meat and milk production o Acute fascioliosis ▪ Distended, painful abdomen ▪ Anemia ▪ Death o “Black disease” = Infectious necrotic hepatitis ▪ Etiologic agent = Clostridium novyi which is frequently present in the GI tract of herbivores ▪ These anaerobic bacteria multiply in the tracts left by migrating liver fluke larvae AND ▪ Produce a powerful necrotizing toxin which results in death of liver tissue ▪ Death is sudden with no well-defined signs, HOWEVER... ▪ Extensive hemorrhage may occur in the subcutaneous tissues, which causes the adjacent skin to turn black F. hepatica: Diagnosis, Treatment & Prevention o Diagnosis ▪ ID of eggs in feces Eggs float poorly Use sedimentation techniques or direct smear ▪ Adults and juveniles found at necropsy o Treatment = Albendazole o Prevention ▪ Snail control ▪ Fence animals away from snail infested areas Paragonimus kellicotti= North American Lung Fluke o Paragonimiasis o DH= Dogs and Cats o IH #1=Snail o IH #2=Crayfish o Prepatent period =3-5 weeks depending on the environment o Found around the Great Lakes and the Mississippi River drainage areas of North America Paragonimus kellicotti Life cycle o Adult P. kellicotti shed eggs in their feces. o The eggs hatch within a couple of weeks, and the larvae enters its first IH, which is a snail. o In the snail, the larva develops into its second stage, then leaves the snail and infects its second IH, a crayfish. o In the crayfish host, the fluke continues to develop, eventually forming a cyst within the tissues of the crayfish. o The crayfish is then eaten by a dog or cat*. o Digestive enzymes cause the cysts to break open, liberating the immature flukes. o These flukes migrate through the dog’s body, reaching the lungs in about 2 weeks. o Once in the lungs, the flukes will pair up and form cysts within the dog’s lungs. o Adult flukes begin to produce eggs within 5-7 weeks. o Fertilized eggs are released from the cysts into the bronchioles of the lungs, where they are coughed up, swallowed, and passed through the intestines into the feces, thus completing the life cycle. * paratenic host of a rodent also possible Clinical signs o Intermittent coughing or difficulty breathing o May cough up bloody mucus o Pneumonia, o Pneumothorax o Severely affected dogs may become weak and lethargic. o Subclinical with mild infections. Diagnosis  o Detecting eggs in a fecal sample (may need to send off to the lab for special testing) o Tracheal wash o Chest x-rays may help with the diagnosis Treatment o No commercial product specifically labeled for treatment o Praziquantel for 3 days o Fenbendazole for 10-14 days