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47 Cards in this Set
- Front
- Back
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The Subkingdom Metazoa contains which 2 phyla?
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1) Phylum Nematoda = roundworms
2) Phylum Platyhelminthes = flatworms = tapeworms |
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Characteristics of Subkingdom Metazoa
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1) All eukaryotic
2) All multicellular, often forming tissues and sometimes organs. |
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Morphology of phylum nematoda
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cylindrical
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Phylum Nematoda characteristics
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1) cylindrical
2) covered w/tough, non-cellular cuticle 3) body cavity contains layers of muscle, longitudinal nerve trunks, digestive, excretory, & reproductive systems 4) separate sexes 5) female produces eggs (hatch outside body or develop into larva w/in body) 6) worm loan & repeated infections contribute to severity of disease |
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Top 3 nematodes in USA
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1) Enterobius vermicularis
2) Ascaris lumbricoides 3) Trichuris trichuria |
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What is the most common nematode in the US?
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Enterobius vermicularis
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AKA for Enterobius vermicularis
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pinworm
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Common life cycle for phylum nematoda
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egg---->larva----->adult
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Female adult of Enterobius vermicularis
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-10 mm
-cream-colored worm w/sharply pointed tail (name pinworm comes from shape of the tail) |
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Male adult of Enterobius vermicularis
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-seldom seen
-3mm |
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Eggs of Enterobius vermicularis
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- microscopic (25 to 50 micrometers)
-flattened on I side -resistant to drying & remain viable for long periods of time |
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How many cases of E. vermicularis
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200 million cases/year worldwide
30 to 40 million cases/yr in the USA |
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Infections w/E. vermicularis are more common in ??
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children
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Larva cycle of E. vermicularis
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-egg--->larva--->adult in 2 wks
-eggs ingested, hatch in upper intestines, larva migrate to cecum, mature into adults & mate -female migrates outside anus & lays 1000s of eggs -female dies |
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Transmission of E. vermicularis
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fecal-oral
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Describe E. vermicularis transmission.
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-anal itching - scratching - eggs to fingers - mouth
-eggs survive environment, contaminate bed linen, shake linens, airborne, inhaled and swallowed |
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Disease caused by E. vermicularis.
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Enterobiasis
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Pathogenicity of E. vermicularis.
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adults produce no intestinal pathogenicity
adults don't cause protective immunity to develop |
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Symptoms of Enterobiasis
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1) pruritis & itching (most severe at night)
2) vaginitis, granulomatous endometritis, salpingitis due to migrating worms 3) does NOT cause appendicitis 4) pyschic effect when we find pinworms |
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Lab Diagnosis of E. vermicularis
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-lab feces is NOT feces
-scotch tape test *eggs are diagnostic |
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Treatment of enterobiasis
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-drugs are available (treat the entire family)
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Prevention of enterobiasis
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-good hygiene (reinfection common)
-NO VACCINE |
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Female morphology of Ascaris lumbricoides.
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-22-35cm long (males are smaller)
-live about 6-10 months |
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Egg morphology of Ascaris lumbricoides
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-35x55 micrometers (microscopic)
-elliptic, w/rough, mamillated, albuminous couting -highly resistant to drying -survive 6 years |
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Life cycle of Ascaris lumbricoides.
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-host ingests eggs
-eggs develop into larva -eggs penetrate intestine -migrate (liver-lung) & breakout in alveolar spaces -humans cough & swallow eggs -egg matures to adult in upper intestines -adults produce eggs (shed in feces) |
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Infectious stage of Ascaris lumbricoides.
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Eggs
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Epidemiology of Ascaris lumbricoides.
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- >1 Billion worldwide population
- 4 million in US - 25,000 tons of eggs passed yearly - more common in warm climates & poor sanitation - human feces in soil (outhouses, etc.) |
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Migration of larva of Ascaris lumbricoides thru lungs causes...
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Type I hypersensitivity (allergic rxn)
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Ascaris lumbricoides causes what in the intestines?
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Bolus (obstruction of bowel)
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Mortality rate of Ascaris lumbricoides
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3% in usa
8,000-10,000 deaths worldwide |
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Symptoms with Ascaris lumbricoides
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- pulmonary type I hypersensitivity (fever, cough, wheezing, shortness or breath)
-common pulmonary features *worm load small (adults asymptomatic) *adult worm migration due to stress -inflammatin & obstruction of appendix, bile duct, pancreatic duct -adult causes bolus -heavy worm loads - abdominal pain malabsorption of nutrients |
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Lab DX of Ascaris lumbricoides
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- specimen = species
- O & P Test - Diagnostic stage = egg and worm - high eosinophil count in WBC w/ microscopic exam |
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Treatment of Ascaris lumbricoides
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drugs
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prevention of Ascaris lumbricoides
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proper disposal of human feces
handwashing NO vaccine |
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Disease caused by Trichuris trichuria?
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1) Trichuriasis
2) Hookworm disease |
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Morphology of T. trichuria
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-male 30-45mm w/ characteristic coiled end (whip shaped)
-female 35-50mm -eggs lemon shaped w/ translucent polar |
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What are diagnostic with T. trichuria?
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Eggs
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What's the 3rd most common nematode in the USA?
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-Trichuris trichuria
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Common patients with T. trichuria
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children
adults |
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Transmission of T. trichuria
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feca-oral
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Pathogenicity of T. trichuriasis
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heavy infections; prolapse (inversion) of rectum
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Treatment of T. trichuriase
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drugs for 3 days
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Prevention of T. trichuriase
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handwashing
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Disease caused by Strongyloides stercoralis
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strongyloidiasis
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AKA for S. stercoralis
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thread worm
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Morphology of S. stercoralis
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-adult worm 2mm in length (smallest of intestinal nematodes)
-Rhabditiform larvae 16x200 micrometers |
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3 life cycles of S. stercoralis
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1) Direct
2) Indirect - only parasite that goes thru this life cycle 3) autoinfection |
