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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*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>
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*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>
  
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===Types:===
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===Transmission:===
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*Roundworm (Ascaris lumbricoides, Toxocara canis)
 
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*Whipworm (Trichuris trichiura)
 
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*Hookworm (Necator americanus, Ancylostoma duodenale)
 
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*Tapeworm (Diphyllobothrium latum, Echinococcus granulosus)
 
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*Cysticercosis (Taenia solium, Taenia saginata)
 
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*Lymphatic filariasis (aka Elephantiasis; Wuchereria bancrofti, Brugia malayi, and Brugia timori)
 
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*Dracunculiasis (aka Guinea Worm disease; Dracunculus medinensis)
 
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*[[Onchocerciasis]] (aka River Blindness; Onchocerca volvulus)
 
−
 
 
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===Transmission:===  
 
 
*No direct person-to-person transmission  
 
*No direct person-to-person transmission  
  
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*Fecal-oral transmission (ingestion of eggs in contaminated soil / vegetables / water)
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*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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**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)
 
**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)
  
−
==History==
+
==Clinical Features==
 +
===History===
 
*Parasitic infections can be in the differential diagnosis for nearly every sign/symptom (GI, dermatologic, neurologic, pulmonary, ophthalmologic, hematologic)
 
*Parasitic infections can be in the differential diagnosis for nearly every sign/symptom (GI, dermatologic, neurologic, pulmonary, ophthalmologic, hematologic)
  
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**symptom chronology
 
**symptom chronology
  
 +
==Types==
 +
{{Helminth Types}}
  
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==Clinical Features==
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==Evaluation==
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===Soil-transmitted helminths (Ascaris roundworm, whipworm, hookworm)===
 
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*Morbidity is related to number of worms harbored in intestines
 
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*Light infections often asymptomatic
 
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*Heavier infections with variety of manifestations including GI symptoms (abdominal pain, diarrhea, blood in stool, rectal prolapse), malaise, weakness, impaired cognitive / physical development, malnutrition
 
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*Hookworm and whipworm infestations also cause iron-deficiency anemia
 
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**Adult worms attach to intestinal wall to feed, causing ongoing luminal blood loss
 
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*Löffler’s syndrome
 
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**Result of Ascaris or hookworm larval transit through the lungs
 
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**Characterized by persistent non-productive cough, chest pain, wheezing, rales, pulmonary infiltrates on CXR and marked eosinophilia
 
−
 
 
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===[[Toxocara canis]]===
 
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*Visceral toxocariasis (visceral larva migrans)
 
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**Larvae travel through liver / lungs / CNS causing fever, cough, enlarged liver, pneumonia
 
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*Ocular toxocariasis (ocular larva migrans)
 
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**Larvae travel to the eye causing inflammation and scarring of retina, usually only one eye, irreversible vision loss
 
−
 
 
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===[[Tapeworm]]===
 
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*Taenia (intestinal)
 
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**Ingestion of eggs results in intestinal infection
 
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**Usually asymptomatic, but heavier infections may result in GI upset, anemia, anorexia, diarrhea
 
−
 
 
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*[[Diphyllobothrium]]
 
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**Usually asymptomatic, may have GI symptoms
 
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**Rarely, migrating proglottids can cause cholangitis, cholecystitis, or intestinal obstruction
 
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**Competes for absorption of vitamin B12, causes pernicious anemia
 
−
 
 
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===[[Echinococcosis]]===
 
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*Larvae travel from small intestine via bloodstream to multiple sites
 
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*Liver is target organ in ⅔ of cases
 
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*Less than 10% of patients have brain involvement (seizures, focal neurologic signs)
 
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*Pulmonary involvement also possible (cough, expectoration of sand-like material, hemoptysis, chest pain, anaphylactoid reaction from leaking cyst, mass effect from expanding cyst)
 
−
 
 
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===[[Cysticercosis]] (Taenia larval cysts)===
 
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*Adult worm matures in intestine, may end up anywhere in body (CNS, muscle, soft tissue, eye, heart, liver)
 
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*Cluster of larvae in the brain forms expanding cyst
 
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*Neurologic symptoms including seizures, AMS, focal neurologic deficit, or hydrocephalus
 
−
 
 
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===[[Lymphatic filiariasis]]===
 
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*Larvae migrate to lymphatic vessels and mature into adults
 
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*Massive peripheral edema with thickening of overlying skin particularly in lower extremities and genitalia 
 
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*Recurrent cellulitis is common
 
−
 
 
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===[[Dracunculiasis]]===
 
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*Adult worm migrates through subcutaneous tissues of the leg and erodes through skin
 
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*Rash, intense pruritus, nausea, vomiting, dyspnea, and diarrhea prior to eruption
 
−
 
 
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==Diagnosis==
 
 
===General===
 
===General===
 
*Stool studies (ova and parasites)
 
*Stool studies (ova and parasites)
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*CBC to identify peripheral eosinophilia or anemia (not sensitive or specific)
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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)
 
*Peripheral blood smear to identify microfilariae (e.g. lymphatic filariasis)
−
+
 
 
===Disease/Symptom Specific===
 
===Disease/Symptom Specific===
 
*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  
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**Neuroimaging (CT with contrast or MR brain) may reveal ring-enhancing lesions, calcifications, or focal enhancing lesions in neurocysticercosis
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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
 
**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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*Identification of adult worm or microscopic larvae in cutaneous ulcer fluid can confirm dracunculiasis
 
*Identification of adult worm or microscopic larvae in cutaneous ulcer fluid can confirm dracunculiasis
  
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===Proposed Diagnostic Criteria for Cysticercosis===
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==Management==
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#1 Definitive diagnosis requires 1 absolute criterion, or 2 major plus 1 minor and 1 epidemiologic criteria.
 
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#2 Probable diagnosis requires 1 major plus 2 minor criteria, or 1 major plus 1 minor plus 1 epidemiologic criteria, or 3 minor plus 1 epidemiologic criteria.
 
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*Absolute
 
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**Demonstration of parasite from biopsy
 
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**Cystic lesion with scolex on neuroimaging
 
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**Direct visualization of parasites on fundoscopic exam
 
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*Major
 
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**Lesions highly suggestive of neurocysticercosis on imaging
 
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**Positive ELISA for anticysticercal antibodies
 
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**Resolution of intracranial lesions after antihelminthic therapy
 
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**Spontaneous resolution of single enhancing lesions
 
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*Minor
 
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**Lesions compatible with neurocysticercosis on imaging
 
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**Clinical symptoms suggestive of neurocysticercosis
 
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**Positive ELISA for antibodies in CSF
 
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**Cysticercosis outside of the nervous system
 
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*Epidemiologic
 
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**Recent travel to endemic area
 
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**Residence in endemic area
 
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**Household contact with Taenia solium infection
 
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−
 
 
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==Clinical Management==
 
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===Soil-transmitted helminthes===
 
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*[[Ascaris]]: albendazole 400 mg x 1 dose OR mebendazole 100 mg BID x 3 days (both high efficacy)
 
−
 
 
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*[[Whipworm]] (Trichuris): albendazole 400 mg x 1 dose
 
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**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)
 
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*[[Hookworm]]: albendazole 400 mg x 1 dose (high efficacy) OR mebendazole 500 mg x 1 dose (low to moderate efficacy)
 
−
 
 
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*Iron supplements in anemia
 
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===Toxocariasis (visceral larva migrans)===
 
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*Diethylcarbamazine 6 mg/kg/day divided TID x 7-10 days OR mebendazole 100-200 mg BID x 5 days OR albendazole 400 mg BID  x 3-5 days
 
−
 
 
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===[[Tapeworm]]===
 
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*Diphyllobothrium
 
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**Praziquantel 5-10 mg/kg x 1 dose
 
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**Replete vitamin B12 if patient has megaloblastic anemia
 
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*[[Echinococcus]]:
 
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**Tissue stage/hydatid disease: albendazole 400 mg BID x 28 days, repeat as needed every 2 weeks x 3 cycles
 
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**Do not aspirate cysts (risk of seeding disease or anaphylactoid reaction from spillage of hydatid sand which contains antigenic proteins)
 
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**Surgical resection of cysts
 
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===[[Cysticercosis]] (Taenia)===
 
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*Neurocysticercosis
 
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**Antiepileptic therapy is first-line treatment
 
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**Treat active disease with caution. Antihelminthic therapy may cause increased inflammation, leading to further tissue damage especially with ocular or spinal involvement
 
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**Ophthalmologic exam before treatment
 
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**Steroids before antihelminthic therapy
 
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**Albendazole 400 mg BID x 8-30 days
 
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**Neurosurgery consult for symptomatic disease (acute obstructive hydrocephalus may occur)
 
−
 
 
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*Intestinal stage
 
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**Praziquantel 5-10 mg/kg x 1 dose
 
−
 
 
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===[[Lymphatic filariasis]]===
 
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*Diethylcarbamazine:
 
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**Day 1: 50 mg PO
 
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**Day 2: 50 mg TID
 
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**Day 3: 100 mg TID
 
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**Days 4-21: 6 mg/kg/day divided TID
 
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*Combined treatment with diethylcarbamazine/albendazole or ivermectin/albendazole may be more effective
 
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*Meticulous skin care to prevent superinfection/cellulitis
 
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*Surgical management of scrotal elephantiasis and chronic lymphatic obstruction
 
−
 
 
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===[[Dracunculiasis]]===
 
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*Metronidazole 750 mg TID x 5-10 days OR thiabendazole 50-75 mg/day divided BID x 3 days
 
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*Must also extract adult worm from skin
 
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*Patients with active skin lesions should stay out of potable water
 
  
 
==See Also==
 
==See Also==
Line 192: Line 62:
 
==External Links==
 
==External Links==
  
−
==Sources==
+
==References==
−
# "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]]

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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