Helminth infections: Difference between revisions

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==Background==
==Background==
*Approximately 2 billion people infected worldwide
*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>
*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>
===Transmission:===
*No direct person-to-person transmission
*Fecal-oral transmission (ingestion of eggs in contaminated soil / vegetables / water)<ref name="rosens"></ref>
**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==
==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 Types}}


==Differential Diagnosis==
==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)


==Workup==
===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<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
*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==
==Management==
==Disposition==


==See Also==
==See Also==
*[[Parasitic Diseases]]
*[[Travel Medicine]]


==External Links==
==External Links==


==Sources==
==References==
<references/>
<references/>
[[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.
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