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
- 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