Gastroenteritis%20-%20parasitic Treatment

Drugs for Treatment of Amoebiasis

• Treatment with a tissue-active amoebicide should always be followed by a luminal cysticidal agent

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

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

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

• 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

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