Parasitology Part 2

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akl273
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194938
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Parasitology Part 2
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2013-01-25 09:11:09
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parasitology
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Fasciola hepatia onward
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    • Fasciola hepatica 
    • Liver fluke
    • zoonosis (cattle/sheep)
  1. What are the definitive hosts of Fasciola hepatica?
    • definitive: 
    • humans, sheep, cattle

    eggs released into water
  2. How is Fasciola hepatica transmitted?
    • eggs released into water
    • --> snail (produces cercari)

    cercari or metacercari sit on watercress for ingestion
  3. How do Fasciola hepatica cause pathology?
    • flukes ingested --> mesenteric veins
    • --> liver
    • migrate through liver and leave tracks

    • adult flukes: 
    • produce eggs in bile ducts
  4. What are the clinical manifestations of Fasciola hepatica infection?
    • young flukes:
    • severe headache
    • backache
    • chills and fever

    • adult flukes:
    • portal vessel atrophy
    • hemorrhage 
    • advanced: liver cirrhosis, diarrhea, anemia
  5. How is Fasciola hepatica infection diagnosed?
    eggs in feces
  6. How is Fasciola hepatica treated and controlled?
    • Triclabendazole
    • **only one not treated with Praziquantel

    • fence off snail habitats
    • kill snails
    • Clonorchis inensis
    • in Southeast Asia
    • zoonotic (reptiles, birds, mammals)
    • causes infection of bile ducts
  7. How is Clonorchis inensis transmitted?
    • dogs, humans produce eggs
    • --> snails
    • --> cercariae --> metacercariae
    • metacercariae ingested by fish
    • --> raw fish eaten by human
  8. What are the clinical manifestations of Clonorchis inensis?
    • 2* to bile duct irritation
    • - Cholangiocarcinoma
  9. How do you diagnose Clonorchis inensis and how is it treated?
    • Diagnose via eggs
    • Treat: Praziquantel
  10. How is Clonorchis inensis controlled?
    • water decontamination
    • cook fish properly
    • prevent discarding of fish carcasses
    • Paragonimus westermani
    • "lung fluke"
    • global distribution
    • definitive hosts: dogs, cats, humans
  11. How is Paragonimus westermani transmitted?
    • eggs released by humans, dogs, cats
    • --> snail --> cercariae
    • metacercariae --> crabs/shrimp

    people ingest crab/shrimp
  12. What are the clinical symptoms of Paragonimus westermani?
    • adults migrate to lungs
    • - cough
    • - blood/eggs in sputum
    • --> diagnosis via eggs
  13. How is Paragonimus westermani treated/controlled?
    Praziquantel

    • control by decreasing snail habitats
    • cook shrimp/crab
  14. What are the characteristics of cestodes?
    • aka tapeworms
    • scolex used for attachments
    • hermaphrodites
    • segments = proglottids
    • Taenia saginata
    • - no hooks on scolex
    • - over 13 branches on proglottid
    • Taenia solium
    • - hook!
    • - less than 13 branches on proglottid
    • Taenia solium **infective
    • Taenia saginata
    • Echinococcus spp. egg

    • contains oncosphere
    • inside proglottid
    • Taenia saginata
    • cysticerci (larvae)
    • grow in muscle (cow)
  15. How is Taenia saginata transmitted?
    • eggs in humans
    • ingested by cows
    • cysticerci (larvae) grow in muscle
    • -->  meat ingested
    • Taenia saginata adult form
    • --> only in humans
    • causes slight abdominal discomfort
  16. How is Taenia saginata treated and controlled?
    • Treat:
    • Niclosamide
    • Praziquantel

    • Control:
    • education, sanitation, cooking/freezing
    • Cysticercus:
    • Taenia saginata/solium
    • **infective

    found in meat (beef)
  17. What is the difference between transmission of Taenia saginata and Taenia solium?
    Taenia solium eggs are infective

    cysticerci in both are infective
  18. How is Taenia solium transmitted?
    • eggs in humans (*infective!)
    • ingested by pigs
    • cysticerci (larvae) grow in muscle
    • --> meat ingested
  19. What are the clinical manifestations of Taenia solium?
    • when eggs ingested (from humans):
    • cysticercosis in humans
    • - in muscle/skin
    • - in eyes (ocular)
    • - in brain (neuro) --> headache, seizure, hallucinations
    • --> death

    **tapeworm
     when cysticerci ingested
    • muscular cysticercosis
    • 2* to Taenia solium
    • neurocysticercosis
    • 2* to Taenia solium

    treat with albendazole/corticosteroids
  20. How is Taenia solium treated?
    • neurocysticercosis:
    • albendazole
    • corticosteroids
    • (but relapse 2* to cyst calcification)

    • adult worms:
    • Niclosamide
    • pumpkin seeds (relax worm)
  21. How is Taenia solium controlled?
    • sanitation
    • treatment (niclosamide)
    • cooking/freezing pork
    • inspection
    • Dipylidium caninum
    • common in dogs/cats
    • sometimes in children

    cysticercoid stage (in fleas)
  22. How is Dipyildium caninum transmitted?
    • egg packets (feces) eaten by fleas
    • cysticercoid in fleas eaten by dogs

    predilection site small intestines
  23. How is Dipylidium caninum diagnosed? What are the clinical symptoms?
    • proglottids (segments) in feces
    • egg packets in feces

    usually asymptomatic
  24. How is Dipylidium caninum treated?
    • Niclosamide
    • Praziquantel
    • Diphyllobothrium latum
    • "broad tapeworm"
    • eggs detected in feces

    hosts: fish-eating animals
  25. How is Diphyllobothrium latum transmitted?
    • eggs (feces) -->
    • freshwater fleas -->
    • freshwater fish -->
    • vertebrates
  26. What is the treatment for Diphyllobothrim latum?
    • praziquantel
    • niclosamide
  27. What are the clinical manifestations of Diphyllobothrium latum?
    megaloblastic anemia

    parasite outcompetes host for vit B12
    • Echinococcus granulosus 
    • - cystic hydatid disease
    • - cystic echinococcosis

    large end contains eggs and shed
  28. What are the definitive hosts of Echinococcus granulosus?
    • dogs, jackals, dingos, coyotes 
    • --> adult tapeworm in intestines

    eat hydatid cysts (protoscolicies)
  29. What are the intermediate hosts of Echinococcus granulosus?
    • humans
    • and everything else

    • eat eggs
    • produce hydatid cysts
    • hydatid cysts (liver/lung)
    • filled with protoscolicies
    • diagnostic in livestock

    • fed to dogs
    • --> adult tapeworm
  30. How does Echinococcus granulosus travel in intermediate hosts?
    • eggs ingested
    • oncosphere penetrates gut
    • --> mesenteric veins
    • --> liver (slow symptoms)
    • --> lungs (fast symptoms)
    • --> elsewhere
    • oncosphere --> metacestode
    • cysts form where stuck
    • Hydatid cysts
    • 2* to Echinococcus granulosus

    • contains protoscolicies
    • +/- laminated membranes
  31. How is Echinoccocus granulosus diagnosed in dogs?
    • autopsy
    • Arecoline purgation
    • coproantigens (dipstick)
  32. What is secondary hydatid disease?
    • 2* to Echinococcus granulosus
    • when cysts spill
    • cysts develop in abdomen
  33. How is Echinococcus granulosus diagnosed in humans?
    • ELISA
    • imaging (X-Ray, CT, MRI, ultrasound)
    • Echinococcus granulosus
    • natural progression
    • CL/CE1/CE2:
    • - active
    • - cysts/daughter cysts
    • CE3: transitional
    • - cysts begin to die
    • C4/C5: inactive
    • - cysts die 
  34. How is Echinococcus granulosus treated surgically?
    • Active phase (unilocular cyst):
    • PAIR with ultrasound guidance
    • penetrate, aspiration, injection, re-aspiration
    • (injection to kill protoscolicies)

    • Active/Transitional (daughter cysts):
    • Albendazole

    • Inactive:
    • wait and watch
  35. How is Echinococcus granulosus treated medically?
    • for inoperable/simple cases
    • albendazole
    • --> laminated membrane peels away
  36. How is Echinococcus granulosus prevented?
    • education
    • "don't feed cysts to dogs"
    • inspection
    • de-worm dogs
    • children with hydatid cysts
    • 2* to Echinococcus granulosus
  37. What are the clinical symptoms of Echinococcus granulosus in humans?
    • abdominal distention
    • abdominal presssure
    • blindness (ocular hydatid cysts)
    • cyst rupture -> anaphylaxis
  38. What is the distribution of Echinococcus multilocularis?
    • Northern temperate climates
    • but widespread
  39. What is Echinococcus multilocularis?
    • Alveolar Hydatid Disease
    • --> multilocular cysts in liver
  40. What are the definitive hosts for Echinococcus multilocularis?
    • foxes
    • wolves
    • domestic dogs
  41. What are the intermediate hosts of Echinococcus multilocularis?
    • eggs infective to:
    • rodents
    • voles, lemmings
    • humans
    • Echinococcus multilocularis
    • in liver
    • tumor-like growth
    • angioma/hematoma appearance
    • --> death without treatment
  42. What is the treatment for Echinococcus multilocularis?
    • Albendazole (lifelong) 
    • - stops growth/spread
    • Hepatectomy
  43. What are some characteristics of nemotodes?
    • host specific
    • eggs develop larvae
    • larvae infective
    • under go hepatic-tracheal migration
  44. What are the geohelminth nematodes?
    • transmitted through soil
    • not zoonotic
    • - hookworms
    • - Ascaris lumbricoides
    • - Trichuris trichuria
    • hookworm egg
    • 30,000 produced per day
    • Ancylostoma duodenale
    • Necator americanus
  45. When do hookworms become infective?
    • L3 larval stage
    • maturation in soil
    • --> skin penetration
    • **Ancylostoma duodenale also transmitted by oral infection
  46. How are hookworms transmitted?
    • eggs in feces
    • -->--> L3 larvae in environment
    • L3 larvae penetrate skin
    • eggs shed in feces
  47. What are the clinical manifestations of hookworm?
    • skin penetration 
    • - ground itch
    • hepatic-tracheal migration:
    • - mild pneumonitis
    • - cough --> hookworms swallowed
    • small intestines
    • - anemia
    • hookworm in small intestines
    • --> macerates microvilli
    • --> pumps blood out
    • --> anemia
  48. What are the symptoms of hookworm anemia (HWA)?
    • tiredness
    • myalgia
    • pallor
    • breathlessness
    • --> leads to generational poverty
    • --> iron deficiency anemia
    • iron deficiency anemia
    • 2* hookworm
    • - hypochromatic/microcytic RBC
    • - pigmented neutrophils
    • - high platelet count
  49. How is hookworm diagnosed?
    • eggs in feces
    • fresh sample
    • (before eggs hatch into larvae)
  50. How is hookworm treated?
    • Albendazole (more effective, single dose, low side effects)
    • Mebendazole
  51. How is hookworm controlled?
    • sanitation
    • school based treatment
    • treat individuals
    • screening not really done anymore
    • Ascaris lumbricoides
    • very common!!
    • widespread (e.g. in Cuba, southeast Asia, etc.)
    • Ascaris lumbricoides egg
    • found in human feces 

    200,000 eggs produced per day
  52. When is Ascaris lumbricoides infective?
    • L2 larval stage
    • ingested from environment
  53. What are the clinical manifestations of Acaris lumbricoides?
    • Larvae:
    • Loeffler's syndrome
    • fever, cough, wheeze, eosinophilia
    • *migration can be seen in lungs

    • Adults:
    • mechanical obstruction, jaundice, appendicitis, diarrhea, asphyxia
    • colic
  54. Where do Ascaris lumbricoides adults live?
    • intestinal parasite
    • **can penetrate other tissues
  55. How is Ascaris lumbricoides diagnosed?
    eggs in stool
  56. How is Ascaris lumbricoides treated?
    • Albendazole
    • Ivermectin
    • --> large numbers of worms excreted
    • Trichuris trichiura
    • whipworm

    • found in human feces 
    • 20,000 eggs per day
  57. When are whipworms infective?
    • L1 larval stage
    • (ingestion)

    no hepato-tracheal migration
    • Trichuris trichiura
    • whipworm

    embeds in cecum
  58. What are the clinical symptoms of Trichuris trichiura?
    • bloody diarrhea
    • abdominal pain
    • 2* rectal prolapse
    • anemia
    • impaired growth
    • reduced cognitive function
  59. What is the treatment for Trichuris trichirua?
    • Albendazole
    • (slightly less effective for T. trichiura vs. other worms)
    • Enterobius vermicularis
    • "pinworm"

    no mortality
    • Enterobius vermicularis egg
    • (pinworm)
  60. How is Enterobius vermicularis transmitted?
    • fecal-oral ingestion
    • L3 eggs

    **NO hepatic-tracheal migration
  61. What are the clinical symptoms of Enterobius vermicularis?
    itchy anus

    • female lays eggs in perianal area at night
    • causes person to itch
    • --> eggs (L3) ingested
  62. How is Enterobius vermicularis treated?
    Albendazole

    prevent via hygiene/treatment
    • Strongyloides stercoralis
    • zoonotic

    • common in children
    • 5 produced per day
  63. What are the hosts for Strongyloides stercoralis?
    humans, dogs
    • Strongyloides stercoralis
    • L3 larvae
    • skin penetrating
  64. How is Strongyloides stercoralis transmitted?
    • skin penetration by L3 larvae
    • (5 larvae per day born)
    • larvae transmitted in feces
    • **can be free-living
    • Larva currens
    • Strongyloides stercoralis
    • --> skin penetration of L3 larvae migrating through skin to hepatic-tracheal migration

    leads to autoinfection
  65. How is Strongyloides stercoralis diagnosed?
    • direct:
    • larvae in fresh stool
    • -> only parasite with larvae in stool
    • -> use as PCR machine

    • indirect: not useful
    • ELISA
    • eosinophilia
  66. What are the acute clinical symptoms of Strongyloidses stercoralis?
    • itchiness
    • cough/wheeze
    • upper abdominal pain
    • diarrhea
    • weight loss
  67. What are the symptoms of chronic Strongyloides stercoralis?
    • intestinal symptoms
    • malabsorption (+/- 2* anemia)
    • smelly yellow stool
    • chronic diarrhea
  68. What is the treatment for Strongyloides stercoralis?
    • Thiabendazole
    • Ivermectin
    • Ancylostoma caninum
    • Ancylostoma braziliense

    • causes Cutaneous Larva Migrans (CLM)
    • Eosinophilic Enteritis (rare)
  69. What are the hosts of Ancylostoma caninum/braziliense?
    dogs, humans

    **cats also share Ancylostoma braziliense
  70. How is Ancylostoma caninum/braziliense transmitted?
    • skin penetration
    • L3 larvae

    • larvae transmitted in feces
    • *can be free-living
  71. What are the clinical manifestations of cutaneous larva migrans in humans?
    • 2* to Ancylostoma caninum/braziliense
    • cutaneous larva migrans
    • - itchiness
    • - 2* bacterial infection
    • no hepatic-tracheal migration (occurs only when parasite infects dogs)


    • Eosinophilic enteritis
    • - L4 larvae found in gut
    • - does not produce eggs
  72. How is Ancylostoma caninum/braziliense diagnosed?
    • clinical symptoms
    • - cutaneous larva migrans
    • - itchiness
    • - pain
  73. How is Ancylostoma caninum/braziliense treated?
    • Ivermectin
    • Albendazole
    • Thiabendazole (topical)
    • Infected cutaneous larva migrans 
    • 2* to Ancylostoma caninum/braziliense infection
    • Eosinophilic enteritis
    • L4 larvae
    • of Ancylostoma caninum
    • found in small intestines 
    • does not produce eggs
  74. How is toxocara canis transmitted to dogs?
    • ingestion of L2 eggs (feces/soil)
    • vertical transmission via placenta
    • L3 larvae in milk
  75. What are the predilection sites of Toxocara canis?
    • dogs: intestines (larvae to go tissues)
    • humans:
    • liver (visceral larva migrans)
    • eye (ocular larva migrans)
  76. How do people become infected with toxocara canis?
    • ingestion of L2 eggs
    • in soil
    • Toxocara canis
    • L2 egg
    • infective stage
    • maturation in environment
  77. What are the clinical symptoms of visceral larva migrans?
    • 2* to Toxocara canis
    • inflammation of internal organs
    • inflammation of CNS
    • fever
    • cough, asthma
    • abdominal pain
    • nausea

    death is rare
    • Toxocara canis with visceral larva migrans
    • occurs in liver
    • --> hepatomegaly, eosinophilia
    • L2 larvae seen
    • Ocular larva migrans
    • Toxocara canis

    • L2 larvae under retina
    • --> retinoblastoma-like appearance

    • eosinophilia --> fibrous granulomata
    • leads to blindness
  78. How is Toxocara canis treated?
    • Albendazole
    • corticosteroids
  79. What is covert toxocariosis?
    • due to Toxocara canis
    • chronic coughing
    • fever
    • abdominal pain
    • headache
    • behavior change
    • associated with asthma
  80. What is neurotoxocariosis?
    • due to Toxocara canis
    • seizures
    • headaches, etc.

    rare!
  81. How is Toxocara canis controlled?
    • deworm puppies
    • deworm kittens
    • Trichinella spp. 
    • zoonosis
    • humans are intermediate host
  82. What are the different types, hosts, and distribution of Trichinella spp.?
    • Trichinella spiralis:
    • pigs, rats, horses
    • Europe/Americas

    • Trichinella nelsoni:
    • hyenas, boar, warthog
    • Africa

    • Trichinella nativa:
    • polar bears, wolves
    • Arctic
  83. How is Trichinella spp. transmitted?
    ingesting raw/undercooked meat
  84. What is the life cycle of Trichinella spp.?
    • L1 larvae ingested
    • reproduce in gut
    • L1 larvae become trapped in muscle
  85. What are the clinical symptoms of Trichinella spp.?
    • Enteric phase (mild):
    • nausea, vomiting, colic, diarrhea, sweating

    • Migratory (invasive) phase:
    • immunopathy, fever, periorbital edema,
    • eosinophilia, myalgia

    • Encystment phase:
    • fever, edema, elevated IgE antibodies
    • dehydration and eosinophilia subside
  86. What is the treatment for Trichinella spp.?
    • Mebendazole
    • prolonged - against larvae
  87. How is Trichinella spp. diagnosed?
    • Direct: Muscle Biopsy
    • Post mortem exam

    Direct: ELISA 
  88. How is Trichinella spp. controlled?
    • freezing meat (except for T. nativa)
    • pig management
    • not feeding meat to horses (T. spiralis)
    • Cooking of meat
  89. What are characteristics of filaria? 
    • L1 microfilariae produced by female
    • --> ingested by vector
    • L1 --> L3 in vector
    • L3 infects human
    • **none are zoonotic!!
    • Loa Loa (filaria)
    • found in central Africa

    subcutaneous human filariasis 
    • Chrysops fly
    • bites during the daytime
    • Loa loa vector
    • picks up L1 microfilariae 
    • bites to release L3
    • Calabar swelling
    • 2* to migration of Loa loa
    • allergic reaction when adult worm damaged during migration
  90. What is the treatment for Loa loa?
    • Ivermectin
    • DEC (**prophylactic)
    • Albendazole
  91. How is Loa loa controlled?
    • light colored clothing
    • insect repellant
    • DEC prophylaxis
    • Dracunculuc medinensis (filaria)
    • found in Sudan, Ghana, Mali, Ethiopia

    • subcutaneous human filariasis
    • guinea worm
    • Cyclops water flea
    • vector for Dracunculuc medinensis (guinea worm)

    • ingests L1 larvae
    • people drink L3 with infected flea
  92. How does Dracunculuc medinensis cause pathology?
    • female migrates to extremities
    • causes painful cutaneous ulcer
    • (debilitating)

    pain relieved by water --> female protrudes uterus to release L1 larvae
  93. What is the treatment for Dracunculuc medinensis?
    • Albendazole
    • Thiabendazole
    • Moist bandage (relieves pain)

    --> relaxes worm to allow faster removal
  94. How is Dracunculuc medinensis controlled?
    • clean drinking water
    • filter/boil water
    • infected not to enter water source

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