gastroenteritis%20-%20parasitic
GASTROENTERITIS - PARASITIC
Frequently, patients with gastrointestinal parasitic infections do not have any signs and symptoms that are specific for parasitic infections (eg fever, malaise, fatigue, sweating, wt loss, anorexia, edema, pruritus).
Some patients may be asymptomatic.
Gastrointestinal symptoms, if present, include diarrhea, abdominal pain, dysentery, flatulence, jaundice, rectal prolapse, dyspepsia, malabsorption, vomiting and biliary colic. 

Pharmacotherapy

Drugs for Treatment of Amoebiasis

Tissue Amoebicides

  • Eg Metronidazole, Tinidazole
  • These agents are effective in treating invasive amoebiasis but are less effective in treating organisms in the bowel lumen

Luminal Amoebicides

  • Eg Diloxanide furoate, Iodoquinol, Paromomycin
  • These agents are effective in treating organisms in the bowel lumen
    • May be used in patients w/ asymptomatic E histolytica infection
  • Recommended for asymptomatic cyst passers
    • To avoid the risk of developing invasive disease
    • To prevent secondary spread
  • When asymptomatic cyst carriage persists after treatment for amoebic dysentery or liver abscess, further treatment w/ a luminal amoebicide is mandatory, otherwise relapse is frequent
  • Paromomycin
    • Temporarily eliminates diarrhea in human immunodeficiency virus (HIV) patients who have cryptosporidiosis
    • May also be used in treatment of cryptosporidiosis & giardiasis

Other Antiprotozoal Drugs

  • Eg Furazolidone, Nitazoxanide, Quinacrine

Furazolidone

  • Used for the treatment of giardiasis
  • Furazolidone is as effective as Metronidazole in the treatment of giardiasis

Nitazoxanide

  • Treatment of choice for giardiasis & cryptosporidium
  • Alternative therapy against F hepatica

Anthelminthics

Albendazole

  • Has an exceptionally broad-spectrum of antiparasitic activity
  • Widely used for intestinal nematode infections
    • Also effective against certain hookworms & roundworms
  • Improved gastrointestinal tract absorption w/ intake of fatty meal

Bithionol

  • Alternative agent for F hepatica when Triclabendazole is unavailable or contraindicated
  • Release of worm antigens may cause reactions (eg urticaria, photosensitivity reactions & gastrointestinal symptoms)

Ivermectin

  • First line therapy against S stercoralis, except in patients w/ Loa loa infection, &/or <15 kg body weight

Mebendazole

  • Widely used for treatment of intestinal nematodes
  • Poorly absorbed from the GI tract, resulting in a low frequency of side effects

Metrifonate

  • Has comparable efficacy w/ Praziquantel in the treatment of S haematobium
  • Action: An organophosphate that is transformed in humans to dichlorvos
    • Potent inhibitor of acetylcholinesterase

Pyrantel pamoate

  • Used for the treatment of intestinal nematodes

Praziquantel

  • Drug of choice for liver flukes (eg Opisthorchis viverrini, Clonorchis sinensis), intestinal flukes, & adult & larval form of cestodes
  • Highly effective against all Schistosoma sp that infect humans
  • Combination therapy w/ Albendazole or Mebendazole is used for schistosomiasis & soil-transmitted helminthiasis
  • Drug resistance is a possibility, especially in countries practicing mass chemotherapy as a control measure
  • Release of worm antigens may elicit responses in the patient (eg nausea & vomiting, abdominal pain, dizziness, headache, lassitude); use w/ caution in patients w/ history of epilepsy

Thiabendazole

  • Active against many intestinal adult nematodes & larval forms in tissues
  • High frequency of untoward effects & the availability of alternative agents have limited its usefulness

Triclabendazole

  • Treatment of choice for patients w/ F hepatica infection
  • Not routinely recommended for children ≤4 years of age

Non-Pharmacological Therapy

Rehydration & Nutrition

Adequate Hydration & Nutrition

  • Patients w/ parasitic infections frequently suffer from malabsorption, vomiting & diarrhea, resulting in malnutrition
  • Ensure that patient’s nutritional & hydration status are maintained at acceptable levels

Replacement of Fluid & Electrolyte Losses

  • Vomiting & diarrhea result in fluid & electrolyte losses, mainly sodium & potassium

Blood Transfusion & Treatment w/ FeSO4

  • These measures may be necessary in hookworm infections which may cause severe anemia
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