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  • imageSingle-dose tinidazole is the preferred 5-nitroimidazole for giardiasis treatment.

  • imageHIV-infected patients with cryptosporidiosis must receive antiretroviral therapy as the mainstay of therapy in addition to antiparasitic therapy.

  • imageEntamoeba histolytica-specific immunoassays are required to diagnose amebiasis because stool sample microscopy does not distinguish between E. histolytica and the nonpathogenic E. dispar.

  • imageMetronidazole and tinidazole are tissue-acting agents against Entamoeba; whereas, paromomycin and iodoquinol are luminal amebicides.

  • imageBenznidazole is the only FDA-approved treatment for Chagas disease.

  • imageChemoprophylaxis with non-chloroquine antimalarial drugs such as atovaquone-proguanil and doxycycline retain effectiveness in areas where chloroquine-resistant P. falciparum exposure is likely.

  • imagePatients with noncalcified parenchymal neurocysticercosis should initially receive symptomatic therapy with corticosteroids and antiepileptic drugs followed by antihelminthic therapy.

  • imageFor head lice, either nonprescription 1% permethrin or pyrethrins plus piperonyl butoxide topical preparations are agents of choice unless local resistance to these agents is documented.

  • imageA single application of 5% permethrin results in cure rates in more than 90% of subjects with scabies at 14 and 28 days, but a second dose should be applied 1 week later because its ovicidal efficacy remains unclear.


Patient Care Process for Giardiasis



  • Patient characteristics: age, recent fluid intake, and description of diarrheal illness (eg, duration, stool appearance)

  • Patient medical history: immunocompromising conditions

  • Social history: alcohol use, recent travel, animal contact, and other high-risk activities (see Table e133-1)

  • Current medications: recent antibiotics, nonprescription laxatives, antidiarrheal medications

  • Objective data

    • Vital signs: temperature, blood pressure, heart rate, respiratory rate, height, weight

    • Physical exam: mucous membrane inspection, skin turgor, abdominal exam, appearance of stool

    • Labs: chemistry panel, urine output, hemoglobin, platelets

    • Diagnostic stool sample evaluation


  • Dehydration (acute), malnutrition, and vitamin deficiencies (chronic)

  • Alternative etiologies based on clinical presentation and risk factors (eg, C. difficile, Cryptosporidium)

  • Medication adherence and preference for tablets versus liquid formulation

  • Likelihood of outbreak based on probable source of Giardia infection (eg, swimming pool, well water)


  • Nonpharmacologic therapy including oral rehydration and hand hygiene

  • Drug therapy regimen including fluid therapy, electrolyte replenishment, and specific anti-infective, dose, route, frequency, and duration (see Table e133-2)

  • Monitoring parameters including efficacy (eg, diarrhea resolution, volume status, electrolyte balance, urine output, serum creatinine) and safety (eg, metallic taste, nausea)

  • Patient education (eg, risk factor avoidance, hand hygiene, purpose of treatment, drug-specific information including antidiarrheal medication avoidance)

  • Self-monitoring for resolution of diarrhea and rehydration


  • Provide patient education regarding all elements of treatment plan

  • Patient or caregiver to ensure additional sick contacts with diarrhea seek care

  • Report confirmed giardiasis case to public health officials

Follow-up: Monitor and Evaluate

  • Resolution of diarrhea within 4 to 7 days following completion of anti-infective regimen

  • Presence of adverse effects (eg, metallic taste, nausea)

  • Avoid recreational water venues for two or more weeks following symptom resolution

*Collaborate with patient, caregivers, and other healthcare professionals.


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