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37 Cards in this Set
- Front
- Back
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Host which contains the larval form of the parasite?
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Intermediate host
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Host which contains the adult sexual form of the parasite?
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Definitive host
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Contain both sexes in one helminth; cestodes and trematodes (except Schistosomes)?
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Hermaphroditic
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Segments filled with eggs?
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Gravid proglottids
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Intestinal Nematodes (Roundworms):
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-Ascaris lumbricoides
-Enterobius vermicularis -Trichuris trichiura -Strongyloides stercoralis -Necator americanus -Ancylostoma duodenale |
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Ascaris lumbricoides
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large intestinal roundworm
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Enterobius vermicularis
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pinworm
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trichuris trichiura
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whipworm
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strongyloides stercoralis
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threadworm
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necator americanus
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new world hookworm
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ancylostoma duodenale
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old world hookworm
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Intestinal Nematodes (roundworms)general characteristics:
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-males smaller than females and have a curved tail
-unsegmented -complete digestive tract -worldwide distribution |
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Ascaris lumbricoides causes...
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-visceral larval migrans-migration through viscera resulting in eosinophilia
-worm ball: blockage of intestine -ascaris pheumonities: due to larvae migration in lungs |
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Ascaris lumbricoides can be diagnosed by:
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-demonstration of egg in feces (round egg containing albuminous coating)
-recovery of worm from anus, nasal passage or sputum |
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Largest nematode?
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Ascaris lumbricoides
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Second most common nematode infection in U.S.?
5-9 y/o most prevalent in U.S. |
Ascaris lumbricoides
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Eggs become embryonated within hours=high rate of autoinfection
*treat entire family of an infected individual* |
Enterobius vermicularis (pinworm)
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Diagnose Enterobius vermicularis by:
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-Scotch tape prepatation
perform after patient has been sleeping or early in the morning |
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Most common helminth parasite of human?
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Enterobius vermicularis
*frequent in children due to poor sanitation habits* |
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Diagnose Trichuris trichuria by
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characteristic egg in feces
football shaped with mucoid polar plugs |
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Clinical disease of Trichuris trichuria?
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prolapsed rectum in heavy infections
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Smallest nematode?
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Strongyloides stercoralis (threadworm)
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Type of infective larvae of Strongyloides stercoralis?
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Filariform larvae
-short buccal cavity -notch at end of tail |
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Where do Strongyloides stercoralis eggs hatch?
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Mucosa of intestine
Rarely seen in feces |
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Stages of Strongyloides stercoralis infection:
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1. cutaneous: initial skin penetration
2. pulmonary: larval migration through lungs 3. Intestinal: symptoms depend of worm load |
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Intestinal nematode with by free living and parasitic cycle?
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Strongyloides stercoralis
Autoinfection: some of the rhabditiform larvae develop into filariform larvae in he bowel and reinfect the host |
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Hyperinfection syndrome of Strongyloides stercoralis occurs with?
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-Immunocompromised (AIDS, drugs)...will exhibit eosinophilia and leukocytosis
-Organ transplantation |
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Hookworm life span?
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2-14 years
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Rarely seen in stools due to attachment to mucosa?
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Hookworm (Necator americanus & Ancylostoma duodenale)
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Differentiate Hookworm Adults?
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Necator: cutting plates
Ancylostoma: 2 pair of teeth |
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Infective stage of hookworm?
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Filariform larvae with long buccal cavity & pointed tail.
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Hookworm larvae has what type of tail?
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Pointed tail
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Strongyloides larvae has what type of tail?
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Notched tail
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Ground itch (allergic rxn) is caused by
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Hookworm (N. americanus & A. duodenale)
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Diagnose hookworm by
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-eggs in feces
-do NOT see larvae in fecus (unless specimen is left at room temp) |
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Anemia is a clinical disease of what type of intestinal nematode?
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Hookworm (N. americanus & A. duodenale)
*Each adult worm consumes 0.2mL of blood/day* |
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Clincal diseases of hookworm?
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-Pheumonitis
-Allergic rxn -Anemia -Cutaneous larvae migrans |
