Difference between revisions of "Helminth infections"

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==Background==
 
==Background==
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*Approximately 2 billion people infected worldwide
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*Many are WHO-designated Neglected Tropical Diseases<ref>The 17 Neglected Tropical Diseases." World Health Organization.  http://www.who.int/neglected_diseases/diseases/en/.  Web. 11 Aug. 2014.</ref>
 +
*At-risk populations include impoverished, children, immigrants, tourists, HIV/AIDS patients, refugees <ref name="CDC">"Parasites." Centers for Disease Control and Prevention.  http://www.cdc.gov/parasites/.  Web. 11 Aug. 2014.</ref>
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*Most common in subtropical and tropical areas, moist climates, poor sanitation and hygiene <ref name="rosens">"Chapter 133 - Parasitic Infections." Rosen's Emergency Medicine: Concepts and Clinical Practice. Ed. John A. Marx, Robert S. Hockberger, and Ron M. Walls. Philadelphia, PA: Mosby Elsevier, 2014. 1768-784.</ref>
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 +
===Transmission:===
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*No direct person-to-person transmission
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 +
*Fecal-oral transmission (ingestion of eggs in contaminated soil / vegetables / water)<ref name="rosens"></ref>
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**Ascaris and whipworm from human feces
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**Toxocara from dog / cat feces
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**Echinococcus from sheep / cattle feces
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**Taenia eggs from human feces
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 +
*Cutaneous transmission
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**Hookworm eggs hatch in the soil, mature larvae penetrate skin
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**Lymphatic filariasis transmitted via bite from infected mosquito (Anopheles, Aedes, and Culex)
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**[[Onchocerciasis]] transmitted via bite from blackflies (Simulium species)
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 +
*Food or waterborne transmission
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**Taenia also transmitted by ingestion of larval cysts in undercooked pork or beef
 +
**Diphyllobothrium tapeworm transmitted by contaminated freshwater fish
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**Dracunculiasis transmitted by ingestion of infected Cyclops water fleas in contaminated water (adult worm erodes through skin of leg, releases larvae in water when host wades in pond / open well, infecting the water fleas)
  
 
==Clinical Features==
 
==Clinical Features==
 +
===History===
 +
*Parasitic infections can be in the differential diagnosis for nearly every sign/symptom (GI, dermatologic, neurologic, pulmonary, ophthalmologic, hematologic)
  
==Differential Diagnosis==
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*Obtain a travel history in every patient
 +
**countries of travel
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**duration of stay
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**activities while traveling (adventure travel, tourism, working, swimming) 
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**living arrangements – city / village / hotel / tent
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**drinking water source
 +
**symptom chronology
  
==Workup==
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==Types==
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{{Helminth Types}}
 +
 
 +
==Evaluation==
 +
===General===
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*Stool studies (ova and parasites)
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*CBC to identify peripheral [[eosinophilia]] or anemia (not sensitive or specific)
 +
*Peripheral blood smear to identify microfilariae (e.g. lymphatic filariasis)
 +
 
 +
===Disease/Symptom Specific===
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*Pulmonary symptoms: CXR and sputum smear (e.g. Löffler’s syndrome)
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*CNS symptoms
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**Neuroimaging (CT with contrast or MR brain) may reveal ring-enhancing lesions, calcifications, or focal enhancing lesions in neurocysticercosis<ref>Del Brutto OH, Rajshekhar V, White A, et al.  “Proposed diagnostic criteria for neurocysticercosis.”  Neurology, 2001; 57:177-183.</ref><ref>Del Brutto OH.  “Diagnostic criteria for neurocysticercosis, revisited.”  Pathogens and Global Health, 2012; 106(5):299-304.</ref>
 +
**CSF serologies/ELISA for echinococcus, cysticercosis
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*Ultrasound or CT can localize cyst of echinococcus
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*ELISA or biopsy of affected tissue to diagnosis toxocariasis, cysticercosis
 +
*Identification of adult worm or microscopic larvae in cutaneous ulcer fluid can confirm dracunculiasis
  
 
==Management==
 
==Management==
 
==Disposition==
 
  
 
==See Also==
 
==See Also==
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*[[Parasitic Diseases]]
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*[[Travel Medicine]]
  
 
==External Links==
 
==External Links==
  
==Sources==
+
==References==
 
<references/>
 
<references/>
  
 
[[Category:ID]]
 
[[Category:ID]]

Latest revision as of 05:07, 5 October 2016

Background

  • Approximately 2 billion people infected worldwide
  • Many are WHO-designated Neglected Tropical Diseases[1]
  • At-risk populations include impoverished, children, immigrants, tourists, HIV/AIDS patients, refugees [2]
  • Most common in subtropical and tropical areas, moist climates, poor sanitation and hygiene [3]

Transmission:

  • No direct person-to-person transmission
  • Fecal-oral transmission (ingestion of eggs in contaminated soil / vegetables / water)[3]
    • Ascaris and whipworm from human feces
    • Toxocara from dog / cat feces
    • Echinococcus from sheep / cattle feces
    • Taenia eggs from human feces
  • Cutaneous transmission
    • Hookworm eggs hatch in the soil, mature larvae penetrate skin
    • Lymphatic filariasis transmitted via bite from infected mosquito (Anopheles, Aedes, and Culex)
    • Onchocerciasis transmitted via bite from blackflies (Simulium species)
  • Food or waterborne transmission
    • Taenia also transmitted by ingestion of larval cysts in undercooked pork or beef
    • Diphyllobothrium tapeworm transmitted by contaminated freshwater fish
    • Dracunculiasis transmitted by ingestion of infected Cyclops water fleas in contaminated water (adult worm erodes through skin of leg, releases larvae in water when host wades in pond / open well, infecting the water fleas)

Clinical Features

History

  • Parasitic infections can be in the differential diagnosis for nearly every sign/symptom (GI, dermatologic, neurologic, pulmonary, ophthalmologic, hematologic)
  • Obtain a travel history in every patient
    • countries of travel
    • duration of stay
    • activities while traveling (adventure travel, tourism, working, swimming)
    • living arrangements – city / village / hotel / tent
    • drinking water source
    • symptom chronology

Types

Helminth infections

Cestodes (Tapeworms)

Trematodes (Flukes)

Nematodes (Roundworms)

Evaluation

General

  • Stool studies (ova and parasites)
  • CBC to identify peripheral eosinophilia or anemia (not sensitive or specific)
  • Peripheral blood smear to identify microfilariae (e.g. lymphatic filariasis)

Disease/Symptom Specific

  • Pulmonary symptoms: CXR and sputum smear (e.g. Löffler’s syndrome)
  • CNS symptoms
    • Neuroimaging (CT with contrast or MR brain) may reveal ring-enhancing lesions, calcifications, or focal enhancing lesions in neurocysticercosis[4][5]
    • CSF serologies/ELISA for echinococcus, cysticercosis
  • Ultrasound or CT can localize cyst of echinococcus
  • ELISA or biopsy of affected tissue to diagnosis toxocariasis, cysticercosis
  • Identification of adult worm or microscopic larvae in cutaneous ulcer fluid can confirm dracunculiasis

Management

See Also

External Links

References

  1. The 17 Neglected Tropical Diseases." World Health Organization. http://www.who.int/neglected_diseases/diseases/en/. Web. 11 Aug. 2014.
  2. "Parasites." Centers for Disease Control and Prevention. http://www.cdc.gov/parasites/. Web. 11 Aug. 2014.
  3. 3.0 3.1 "Chapter 133 - Parasitic Infections." Rosen's Emergency Medicine: Concepts and Clinical Practice. Ed. John A. Marx, Robert S. Hockberger, and Ron M. Walls. Philadelphia, PA: Mosby Elsevier, 2014. 1768-784.
  4. Del Brutto OH, Rajshekhar V, White A, et al. “Proposed diagnostic criteria for neurocysticercosis.” Neurology, 2001; 57:177-183.
  5. Del Brutto OH. “Diagnostic criteria for neurocysticercosis, revisited.” Pathogens and Global Health, 2012; 106(5):299-304.