Difference between revisions of "Helminth infections"

(Cysticercosis (Taenia larval cysts))
(Reefernces added)
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==Background==
 
==Background==
*Approximately 2 billion people infected worldwide  
+
*Approximately 2 billion people infected worldwide
*Many are WHO-designated Neglected Tropical Diseases
+
*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  
+
*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  
+
*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:===  
 
===Transmission:===  
 
*No direct person-to-person transmission  
 
*No direct person-to-person transmission  
  
*Fecal-oral transmission (ingestion of eggs in contaminated soil / vegetables / water)
+
*Fecal-oral transmission (ingestion of eggs in contaminated soil / vegetables / water)<ref name="rosens"></ref>
 
**Ascaris and whipworm from human feces
 
**Ascaris and whipworm from human feces
 
**Toxocara from dog / cat feces
 
**Toxocara from dog / cat feces
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*Morbidity is related to number of worms harbored in intestines
 
*Morbidity is related to number of worms harbored in intestines
 
*Light infections often asymptomatic
 
*Light infections often asymptomatic
*Heavier infections with variety of manifestations including GI symptoms (abdominal pain, diarrhea, blood in stool, rectal prolapse), malaise, weakness, impaired cognitive / physical development, malnutrition
+
*Heavier infections with variety of manifestations including GI symptoms (abdominal pain, diarrhea, blood in stool, rectal prolapse), malaise, weakness, impaired cognitive / physical development, malnutrition<ref>Wilcox S, Thomas S, Brown D, Nadel E.  “Gastrointestinal Parasite.”  The Journal of Emergency Medicine, 2007; 33(3):277-280</ref></ref>
 
*Hookworm and whipworm infestations also cause iron-deficiency anemia
 
*Hookworm and whipworm infestations also cause iron-deficiency anemia
 
**Adult worms attach to intestinal wall to feed, causing ongoing luminal blood loss
 
**Adult worms attach to intestinal wall to feed, causing ongoing luminal blood loss
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===[[Tapeworm]]===
 
===[[Tapeworm]]===
*Taenia (intestinal)
+
*Taenia (intestinal)<ref name="CDC"></ref>
 
**Ingestion of eggs results in intestinal infection
 
**Ingestion of eggs results in intestinal infection
 
**Usually asymptomatic, but heavier infections may result in GI upset, anemia, anorexia, diarrhea
 
**Usually asymptomatic, but heavier infections may result in GI upset, anemia, anorexia, diarrhea
  
 
*[[Diphyllobothrium]]  
 
*[[Diphyllobothrium]]  
**Usually asymptomatic, may have GI symptoms
+
**Usually asymptomatic, may have GI symptoms<ref name="CDC"></ref>
 
**Rarely, migrating proglottids can cause cholangitis, cholecystitis, or intestinal obstruction
 
**Rarely, migrating proglottids can cause cholangitis, cholecystitis, or intestinal obstruction
 
**Competes for absorption of vitamin B12, causes pernicious anemia
 
**Competes for absorption of vitamin B12, causes pernicious anemia
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*Pulmonary symptoms: CXR and sputum smear (e.g. Löffler’s syndrome)
 
*Pulmonary symptoms: CXR and sputum smear (e.g. Löffler’s syndrome)
 
*CNS symptoms  
 
*CNS symptoms  
**Neuroimaging (CT with contrast or MR brain) may reveal ring-enhancing lesions, calcifications, or focal enhancing lesions in neurocysticercosis
+
**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
 
**CSF serologies/ELISA for echinococcus, cysticercosis
 
*Ultrasound or CT can localize cyst of echinococcus
 
*Ultrasound or CT can localize cyst of echinococcus
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*[[Whipworm]] (Trichuris): albendazole 400 mg x 1 dose
 
*[[Whipworm]] (Trichuris): albendazole 400 mg x 1 dose
**Historically treated with albendazole or mebendazole, but monotherapy has low efficacy against Trichuris especially in heavy infections; higher cure rate achieved with oxantel pamoate-albendazole combination compared to any monotherapy in recent RCT (Speich, et al. NEJM 2014; 370:610-620)
+
**Historically treated with albendazole or mebendazole, but monotherapy has low efficacy against Trichuris especially in heavy infections; higher cure rate achieved with oxantel pamoate-albendazole combination compared to any monotherapy in recent RCT <ref>Speich B, Ame S, et al. "Oxantel Pamoate–Albendazole for Trichuris Trichiura Infection." New England Journal of Medicine, 2014; 370: 610-620.</ref>
  
 
*[[Hookworm]]: albendazole 400 mg x 1 dose (high efficacy) OR mebendazole 500 mg x 1 dose (low to moderate efficacy)
 
*[[Hookworm]]: albendazole 400 mg x 1 dose (high efficacy) OR mebendazole 500 mg x 1 dose (low to moderate efficacy)
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==Sources==
 
==Sources==
# "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.
 
# "The 17 Neglected Tropical Diseases." World Health Organization.  http://www.who.int/neglected_diseases/diseases/en/.  Web. 11 Aug. 2014.
 
# "Parasites." Centers for Disease Control and Prevention.  http://www.cdc.gov/parasites/.  Web. 11 Aug. 2014.
 
# Wilcox S, Thomas S, Brown D, Nadel E.  “Gastrointestinal Parasite.”  The Journal of Emergency Medicine, 2007; 33(3):277-280
 
# Del Brutto OH, Rajshekhar V, White A, et al.  “Proposed diagnostic criteria for neurocysticercosis.”  Neurology, 2001; 57:177-183.
 
# Del Brutto OH.  “Diagnostic criteria for neurocysticercosis, revisited.”  Pathogens and Global Health, 2012; 106(5):299-304.
 
# Speich B, Ame S, et al. "Oxantel Pamoate–Albendazole for Trichuris Trichiura Infection." New England Journal of Medicine, 2014; 370: 610-620.
 
 
<references/>
 
<references/>
  
 
[[Category:ID]]
 
[[Category:ID]]

Revision as of 23:14, 6 September 2014

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)

Differential Diagnosis

Types:

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

Soil-transmitted helminths (Ascaris roundworm, whipworm, hookworm)

  • Morbidity is related to number of worms harbored in intestines
  • Light infections often asymptomatic
  • Heavier infections with variety of manifestations including GI symptoms (abdominal pain, diarrhea, blood in stool, rectal prolapse), malaise, weakness, impaired cognitive / physical development, malnutrition[4]</ref>
  • Hookworm and whipworm infestations also cause iron-deficiency anemia
    • Adult worms attach to intestinal wall to feed, causing ongoing luminal blood loss
  • Löffler’s syndrome
    • Result of Ascaris or hookworm larval transit through the lungs
    • Characterized by persistent non-productive cough, chest pain, wheezing, rales, pulmonary infiltrates on CXR and marked eosinophilia

Toxocara canis

  • Visceral toxocariasis (visceral larva migrans)
    • Larvae travel through liver / lungs / CNS causing fever, cough, enlarged liver, pneumonia
  • Ocular toxocariasis (ocular larva migrans)
    • Larvae travel to the eye causing inflammation and scarring of retina, usually only one eye, irreversible vision loss

Tapeworm

  • Taenia (intestinal)[2]
    • Ingestion of eggs results in intestinal infection
    • Usually asymptomatic, but heavier infections may result in GI upset, anemia, anorexia, diarrhea
  • Diphyllobothrium
    • Usually asymptomatic, may have GI symptoms[2]
    • Rarely, migrating proglottids can cause cholangitis, cholecystitis, or intestinal obstruction
    • Competes for absorption of vitamin B12, causes pernicious anemia

Diagnosis

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[5][6]
    • 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

Clinical Management

Soil-transmitted helminthes

  • Ascaris: albendazole 400 mg x 1 dose OR mebendazole 100 mg BID x 3 days (both high efficacy)
  • Whipworm (Trichuris): albendazole 400 mg x 1 dose
    • Historically treated with albendazole or mebendazole, but monotherapy has low efficacy against Trichuris especially in heavy infections; higher cure rate achieved with oxantel pamoate-albendazole combination compared to any monotherapy in recent RCT [7]
  • Hookworm: albendazole 400 mg x 1 dose (high efficacy) OR mebendazole 500 mg x 1 dose (low to moderate efficacy)
  • Iron supplements in anemia

See Also

External Links

Sources

  1. The 17 Neglected Tropical Diseases." World Health Organization. http://www.who.int/neglected_diseases/diseases/en/. Web. 11 Aug. 2014.
  2. 2.0 2.1 2.2 "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. Wilcox S, Thomas S, Brown D, Nadel E. “Gastrointestinal Parasite.” The Journal of Emergency Medicine, 2007; 33(3):277-280
  5. Del Brutto OH, Rajshekhar V, White A, et al. “Proposed diagnostic criteria for neurocysticercosis.” Neurology, 2001; 57:177-183.
  6. Del Brutto OH. “Diagnostic criteria for neurocysticercosis, revisited.” Pathogens and Global Health, 2012; 106(5):299-304.
  7. Speich B, Ame S, et al. "Oxantel Pamoate–Albendazole for Trichuris Trichiura Infection." New England Journal of Medicine, 2014; 370: 610-620.