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26 Cards in this Set
- Front
- Back
Case Presentation
A 3 year old child in Haiti has abdominal pain and a swollen abdomen Examination reveals distension with a mass. Intestines reveal lots of worms... |
Ascaris lumbricoides
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Ascaris lumbricoides
Infection pathway: |
Females longer than males because they harbor eggs
Feces powder gets in dirt, may get on food, or aspirated, gets into pulmonary capillaries from gut absorption or from alveoli, embolize there, crawl back to airspaces, into trachea, and then are swallowed into intestine, then they mature. |
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Ascaris: a “soil-transmitted helminth”
Occasionally seen in __________ USA Eggs hardy? Migrating larvae can cause ________ ____________ Migrating larvae can cause? Symptoms? Ascaris worms can cause _______ or __________ obstruction Treatment? |
Occasionally seen in Southeastern USA
Female worms produce large numbers of eggs that can survive in the environment. Migrating larvae can cause eosinophilic pneumonia Infections are often asymptomatic. However, Ascaris worms can cause biliary or intestinal obstruction. Easily treated with mebendazole. |
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PARASITIC HELMINTHS
__________ (e.g., Ascaris, trichinella, filaria, strongyloides, trichuris,etc.) _________ a) Trematodes (e.g., schistosomes, clonorchis, other flukes) b) Cestodes (tapeworms) |
Roundworms (nematodes)
(e.g., Ascaris, trichinella, filaria, strongyloides, trichuris,etc.) Flatworms a) Trematodes (e.g., schistosomes, clonorchis, other flukes) b) Cestodes (tapeworms) |
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Helminths: General features
Host specificity (_____ and _____ hosts) Lack of ___________ in human host Infection vs. infestation? Disease often related to _________ intensity Polyparasitism |
Host specificity (definitive and intermediate hosts)
Lack of multiplication in human host Infection vs. infestation: Many infections are asymptomatic Disease often related to infection intensity Polyparasitism - if you have one, you can have another one |
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Helminths: Pathogenesis
(4) |
Tissue invasion
Deprive host of essential nutrients Mass effect or physical obstruction Stimulate harmful immune responses - immunopathology |
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Diagnostic Options in Parasitology
Name several |
Traditional Methods
- Microscopy, Xenodiagnosis, Skin Tests Enhanced Microscopy Antigen Detection Antibody Assays DNA Detection |
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Therapy of Helminth Infections
General themes - Neurotransmission? - Motility - ? Which one is agonist for both mammalian / worm chloride channels) Which ones bind tubulin? |
Shared metabolic pathways (causes toxicity issues)
Drug delivery to site of infection General themes - Neurotransmission - Ivermectin vs. Nematodes (agonist for both mammalian / worm chloride channels) - Motility - Mebendazole / Albendazole bind Tubulin - Interaction with Host Immune System - Praziquantel in Schistosomiasis |
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“Scotch tape test” shows?
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“Scotch tape test” shows bean-shaped eggs of Enterobius vermicularis
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A 3 year old child in rural China has growth retardation and lassitude
hook worm found in stool (thin delicate shell) |
Ancylostoma duodenale egg
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Relationship between hookworm infection intensity and hemoglobin levels (old data from Dominican Republic)
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Positively correlated - more severe infection --> more severe anemia
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Hookworm: Clinical features?
- due to larval invasion - due to worms reaching small intestine - due to worms action at small intestine Treat with? all these worms are so bendy.... |
Ground itch (larval invasion)
Abdominal pain (when worms reach small intestine) Anemia Treat with mebendazole / albendazole |
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Host specificity: Cutaneous larval migrans
Can dog and cat hookworm larvae complete migration in humans? |
No,
Dog and cat hookworm larvae are unable to complete migration in humans. |
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Strongyloidiasis: Clinical summary
Epidemiology similar to _______, but higher/lower?______ infection rates. Symptoms? _____________* patients may have the hyperinfection syndrome with disseminated infection and sepsis. |
Epidemiology similar to hookworm, but lower infection rates.
Clinical manifestations are variable: many asymptomatic Some people have lower abd rash, “larva currens” Abdominal bloating, sometimes with diarrhea, weight loss Immunosuppressed* patients may have the hyperinfection syndrome with disseminated infection and sepsis. * Steroids, chemotherapy, transplant recipients, pregnancy, alcohol abuse or malnutrition, HTLV-1 |
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Strongyloidiasis: Clinical summary
Diagnosis: Stool examination does NOT show what? instead it shows? Treatment: |
Diagnosis: Stool examination (larvae, not eggs)
Treatment: Ivermectin |
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Trichinosis
Host(s)? Symptoms? Treatments/Prevention? |
Hosts: Broad host range (rodents, pigs, humans)
Symptoms: Fever, myalgia (muscle pain = light bulb), eosinophilia Albendazole (questionable), steroids to dec. inflammation Cook meat thoroughly to eliminate cysts in meat muscle |
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Trichinosis
Life Cycle Ingestion of _______ _______ (e.g. ____) --> larva released in _____ ________ --> larvae deposited in ________ --> _______ larva in ________ _________ --> Repeat |
Ingestion of undercooked meat (e.g. pork) --> larva released in small intestine --> larvae deposited in mucosa --> encysted larva in striated muscle --> Repeat
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What is Filariasis?
Target organs? Intestine involved? |
Insect-borne nematode infections
8 species infect humans Other species infect animals (heartworms) Target organs: eyes, skin, lymphatics, heart No intestine involved - mosquito bourne disease |
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Filariasis Life cycle
_________takes a blood meal (L3 larvae enter skin)--> adults go into lymphatic system --> adults produce _______________ that migrate into lymph and bood channels --> another mosquito takes a blood meal (ingests a ________) ---> __________ shed sheats, penetrate mosquito midgut and migrates to thoracic muscle, --> larvae travel to mosquito head and proboscus -->Repeat |
Mosquito takes a blood meal (L3 larvae enter skin)--> adults go into lymphatic system --> adults produce sheathed microfilariae (not eggs) that migrate into lymph and bood channels --> mosquito takes a blood meal (ingests a microfilariae) ---> microfilariae shed sheats, penetrate mosquito midgut and migrates to thoracic muscle, --> larvae travel to mosquito head and proboscus --> mosquito takes a blood meal from human and infects
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Bancroftian filariasis?
Bancroftian = Wuchereria Bancrofti |
Causes severe hydrocele and genital elephantiasis
A hydrocele denotes a pathological accumulation of serous fluid in a bodily cavity. |
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Diagnosis:
Treatment of filariasis |
Filariasis pregnancy test type thing
Albendazole Diethylcarbamazine (emphased in CMMRS) Ivermectin |
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Onchocerca. volvulus
Vector: __________ Diagnosis: ____________ Adult worms live in __________ __________ May lead to "__________ ___________"(hallmark manifestation) |
Onchocerca. volvulus
Vector: Simulium BLACK flies Diagnosis: Microfilariae in skin snips Adult worms live in subcutaneous nodules May lead to "River Blindness"(hallmark manifestation) |
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Eye Exam
Onchocerciasis: shows ? Can cause? Disease cased by? |
Eye Exam
Onchocerciasis: shows Punctate keratitis (snowflakes) or Sclerosing keratitis Can cause blindness Disease caused by inflammatory reaction to microfilariae |
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Other Onchocercal manifestations aside from visual symptoms?
Disease caused by? |
Onchocecal dermatitis
Caused by inflammatory response to microfilariae |
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Onchocerciasis Treatment
____________(Mectizan, donated by Merck) Interferes with __________ in nematodes Clears __________ from skin and eyes of oncho patients This effect is (temporary/permanent) _______; the drug _______ (does/does not) kill adult worms Safe for use in ______ ___________ ____________ Effective? |
Ivermectin (Mectizan, donated by Merck)
Interferes with neurotransmission in nematodes Clears microfilariae from skin and eyes of oncho patients This effect is temporary; the drug does not kill adult worms Safe for use in mass treatment programs Vector control and ivermectin have have largely eliminated severe disease in many areas in Africa and the Americas |
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Treatment:
__________ (8 weeks) clears Wolbachia and sterilizes O. volvulus |
Doxycycline (8 weeks) clears Wolbachia and sterilizes O. volvulus
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