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. 

Gastroenteritis%20-%20parasitic Treatment

Pharmacotherapy

Drugs for Treatment of Amoebiasis

  • Treatment with a tissue-active amoebicide should always be followed by a luminal cysticidal agent
Recommended Therapy for Protozoal Parasites
Pathogen

Drug
Preferred Agents Alternative Agents
Cryptosporidium sp
Nitazoxanide -
Entamoeba histolytica (Amoebiasis)
- Asymptomatic cyst passer
Paromomycin Iodoquinol or Diloxanide furoate
E histolytica (Amoebiasis)
- Mild-moderate intestinal disease
Metronidazole or Tinidazole -
E histolytica (Amoebiasis)
- Severe intestinal disease or liver abscess
Metronidazole or Tinidazole
-
Giardia lamblia (Giardiasis)

In most immunocompetent patients, giardiasis is self-limiting and does not require treatment. In nonendemic areas, asymptomatic carriers of giardiasis are treated
Metronidazole, Nitazoxanide or Tinidazole
Furazolidone, Paromomycin or Quinacrine

Tissue Amoebicides

  • Eg Metronidazole, Ornidazole, 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 (preferred)
  • These agents are effective in treating organisms in the bowel lumen
    • May be used in patients with 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 with a luminal amoebicide is mandatory, otherwise relapse is frequent
  • Paromomycin
    • Drug of choice for asymptomatic intestinal infection with E histolytica 
    • Temporarily eliminates diarrhea in human immunodeficiency virus (HIV) patients who have cryptosporidiosis
    • May also be used in treatment of cryptosporidiosis and 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 and cryptosporidium
  • Alternative therapy against F hepatica

Anthelminthics

Recommended Therapy for Helminths
Pathogen

Drug
Preferred Agents Alternative Agents
Cestodes (Tapeworms)
Taenia saginata (beef tapeworm), Taenia solium (pork tapeworm), Taenia asiatica (Asian tapeworm)
Praziquantel Niclosamide
Diphyllobothrium caninum, Diphyllobothrium latum (fish or broad tapeworm) Praziquantel
Niclosamide
Hymenolepis nana (dwarf tapeworm) Praziquantel   Niclosamide or Nitazoxanide
Nematodes (Roundworms)
Ascaris lumbricoides (Ascariasis)
Albendazole, Ivermectin or Mebendazole
Nitazoxanide
Ancylostoma duodenale, Necator americanus (Ancylostomiasis) (Hookworms)
Albendazole, Mebendazole or Pyrantel pamoate
-
Capillaria philippinensis (Capillariasis) Mebendazole  Albendazole 
Enterobius vermicularis (Pinworm)  Pyrantel pamoate, Albendazole or Mebendazole   -
Strongyloides stercoralis (Strongyloidiasis)  Ivermectin  Albendazole or Thiabendazole 
Trichuris trichiura (Whipworm) Mebendazole  Albendazole or Ivermectin
Trematodes (Flukes)
Clonorchis sinensis (Oriental liver fluke)  Praziquantel  Albendazole 
Fasciola hepatica (Fascioliasis)  Triclabendazole  Bithionol or Nitazoxanide 
Fasciolopsis buski, Heterophyes heterophyes, Metagonimus yokogawai (Intestinal flukes)  Praziquantel  -
Opisthorchis viverrini (Southeast Asian liver fluke) Praziquantel  Albendazole
Paragonimus westermani (Lung flukes)
Praziquantel  Triclabendazole or Bithionol
Schistosoma haematobium  Praziquantel  -
Schistosoma japonicum  Praziquantel  -
Schistosoma mansoni  Praziquantel  Oxamniquine

Albendazole

  • Has an exceptionally broad-spectrum of antiparasitic activity
  • Widely used for intestinal nematode infections
    • Also effective against certain hookworms and roundworms
  • Improved gastrointestinal tract absorption with 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 and gastrointestinal symptoms)

Ivermectin

  • First-line therapy against S stercoralis, except in patients with Loa loa infection, and/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

Oxantel pamoate

  • An analogue of Pyrantel, used in combination with Albendazole or Ivermectin as an alternative treatment option for T trichiura

Pyrantel pamoate

  • Used for the treatment of intestinal nematodes

Praziquantel

  • Drug of choice for liver flukes (eg Opisthorchis viverrini, Clonorchis sinensis), intestinal flukes, and adult and larval form of cestodes
  • Highly effective against all Schistosoma sp that infect humans
  • Combination therapy with Albendazole or Mebendazole is used for schistosomiasis and 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 and vomiting, abdominal pain, dizziness, headache, lassitude); use with caution in patients with history of epilepsy

Thiabendazole

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

Triclabendazole

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

Non-Pharmacological Therapy

Rehydration and Nutrition
Adequate Hydration and Nutrition

  • Patients with parasitic infections frequently suffer from malabsorption, vomiting and diarrhea, resulting in malnutrition
  • Ensure that patient’s nutritional and hydration status are maintained at acceptable levels
Replacement of Fluid and Electrolyte Losses
  • Vomiting and diarrhea result in fluid and electrolyte losses, mainly sodium and potassium, and these patients should be assessed for signs of dehydration
  • May initiate oral rehydration therapy using oral rehydration solution (ORS) for patients with indications for fluid and electrolyte replacement
  • ORS concentration recommended by the World Health Organization (WHO): 75 mEq/L sodium, 75 mmol/L glucose with total osmolarity of 245 mOsm/L, or ½ teaspoon of salt and 6 teaspoons of sugar in 1 L of water
  • The WHO-recommended amount to be given for each fl uid loss based on weight and age are as follows:
  • Weight Age Amount (within the first 4 hours)
    <5 kg (11 lb)
    <4 months
    200-400 mL 
     5-7.9 kg (11 lb - 17 lb, 7 oz)  4-11 months 200-400 mL 
     8-10.9 kg (17 lb, 10 oz - 24 lb)  4-11 months 600-800 mL 
    11-15.9 kg (24 lb, 4 oz - 35 lb)   2-4 years  800-1200 mL
     16-29.9 kg (35 lb, 4 oz - 65 lb, 15 oz)  5-14 years  1200-2200 mL
    30 kg (66 lb, 2 oz) or more   ≥15 years  2200-4000 mL
Blood Transfusion and Treatment with Ferrous sulfate
  • These measures may be necessary in hookworm infections which may cause severe anemia
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