An amebicide (or amoebicide) is an agent that is destructive to amoeba, especially parasitic amoeba that cause amoebiasis. [1]
E. histolytica infections occur in both the intestine and (in people with symptoms) in tissue of the intestine and/or liver. [2] As a result, both tissue and luminal drugs are needed to treat the infection, one for each location. Metronidazole is usually given first, followed by Paromomycin or Diloxanide.
E. dispar does not require treatment, but many laboratories (even in the developed world) do not have the facilities to distinguish this from E. histolytica.
Metronidazole, or a related drug such as tinidazole, secnidazole or ornidazole, is used to destroy amoebae that have invaded tissue. [2] These are rapidly absorbed into the bloodstream and transported to the site of infection. Because they are rapidly absorbed there is almost none remaining in the intestine.
For amebic dysentery a multi-prong approach must be used, starting with one of:
Doses for children are calculated by body weight and a pharmacist should be consulted for help.
Since most of the amoebae remain in the intestine when tissue invasion occurs, it is important to get rid of those also or the patient will be at risk of developing another case of invasive disease. Several drugs are available for treating intestinal infections, the most effective of which has been shown to be paromomycin (also known as Humatin); iodoquinol (also known as Yodoxin) is used in the US; and diloxanide furoate (also known as Furamide) is used in certain other countries.
In addition to the tissue amebicides above, one of the following lumenal amebicides should be prescribed as an adjunctive treatment, either concurrently or sequentially, to destroy E. histolytica in the colon:
Doses for children are calculated by body weight and a pharmacist should be consulted for help.
For amebic liver abscess:
Doses for children are calculated by body weight and a pharmacist should be consulted for help.
Propamidine isethionate has been used in the treatment of Acanthamoeba infection. [3]
The Nicobarese people have attested to the medicinal properties found in Glochidion calocarpum , a plant endemic to India, saying that its bark and seed are most effective in curing abdominal disorders associated with amoebiasis. [4]
Although Naegleria is sometimes considered amoeboid, unlike Acanthamoeba or Balamuthia it is not closely related to the Amoebozoa (it is much more closely related to Leishmania ) and agents used to treat Naegleria infections are usually addressed separately.
Entamoeba is a genus of Amoebozoa found as internal parasites or commensals of animals.
Dysentery is a type of gastroenteritis that results in bloody diarrhea. Other symptoms may include fever, abdominal pain, and a feeling of incomplete defecation. Complications may include dehydration.
Metronidazole, marketed under the brand name Flagyl among others, is an antibiotic and antiprotozoal medication. It is used either alone or with other antibiotics to treat pelvic inflammatory disease, endocarditis, and bacterial vaginosis. It is effective for dracunculiasis, giardiasis, trichomoniasis, and amebiasis. It is an option for a first episode of mild-to-moderate Clostridium difficile colitis if vancomycin or fidaxomicin is unavailable. Metronidazole is available by mouth, as a cream, and by injection into a vein.
Entamoeba histolytica is an anaerobic parasitic amoebozoan, part of the genus Entamoeba. Predominantly infecting humans and other primates causing amoebiasis, E. histolytica is estimated to infect about 35-50 million people worldwide. E. histolytica infection is estimated to kill more than 55,000 people each year. Previously, it was thought that 10% of the world population was infected, but these figures predate the recognition that at least 90% of these infections were due to a second species, E. dispar. Mammals such as dogs and cats can become infected transiently, but are not thought to contribute significantly to transmission.
Free-living amoebae in the Amoebozoa group are important causes of disease in humans and animals.
Amoebozoa is a major taxonomic group containing about 2,400 described species of amoeboid protists, often possessing blunt, fingerlike, lobose pseudopods and tubular mitochondrial cristae. In most classification schemes, Amoebozoa is ranked as a phylum within either the kingdom Protista or the kingdom Protozoa. In the classification favored by the International Society of Protistologists, it is retained as an unranked "supergroup" within Eukaryota. Molecular genetic analysis supports Amoebozoa as a monophyletic clade. Most phylogenetic trees identify it as the sister group to Opisthokonta, another major clade which contains both fungi and animals as well as some 300 species of unicellular protists. Amoebozoa and Opisthokonta are sometimes grouped together in a high-level taxon, variously named Unikonta, Amorphea or Opimoda.
Naegleriasis is an almost invariably fatal infection of the brain by the free-living unicellular eukaryote Naegleria fowleri. Symptoms are meningitis-like and include headache, fever, nausea, vomiting, a stiff neck, confusion, hallucinations and seizures. Symptoms progress rapidly over around five days, and death usually results within one to two weeks of symptoms.
Granulomatous amoebic encephalitis (GAE) is a rare, usually fatal, subacute-to-chronic central nervous system disease caused by certain species of free-living amoebae of the genera Acanthamoeba, Balamuthia and Sappinia pedata. The term is most commonly used with Acanthamoeba. In more modern references, the term "balamuthia amoebic encephalitis" (BAE) is commonly used when Balamuthia mandrillaris is the cause.
Antiprotozoal agents is a class of pharmaceuticals used in treatment of protozoan infection.
Miltefosine, sold under the trade name Impavido among others, is a medication mainly used to treat leishmaniasis and free-living amoeba infections such as Naegleria fowleri and Balamuthia mandrillaris. This includes the three forms of leishmaniasis: cutaneous, visceral and mucosal. It may be used with liposomal amphotericin B or paromomycin. It is taken by mouth.
Antiparasitics are a class of medications which are indicated for the treatment of parasitic diseases, such as those caused by helminths, amoeba, ectoparasites, parasitic fungi, and protozoa, among others. Antiparasitics target the parasitic agents of the infections by destroying them or inhibiting their growth; they are usually effective against a limited number of parasites within a particular class. Antiparasitics are one of the antimicrobial drugs which include antibiotics that target bacteria, and antifungals that target fungi. They may be administered orally, intravenously or topically.
The quinoline derivative diiodohydroxyquinoline (INN), or iodoquinol (USAN), can be used in the treatment of amoebiasis.
Diloxanide is a medication used to treat amoeba infections. In places where infections are not common, it is a second line treatment after paromomycin when a person has no symptoms. For people who are symptomatic, it is used after treatment with metronidazole or tinidazole. It is taken by mouth.
Amoebiasis or amoebic dysentery, is an infection caused by any of the amoebae of the Entamoeba genus. Symptoms are most common during infection by Entamoeba histolytica. Amoebiasis can be present with no, mild, or severe symptoms. Symptoms may include abdominal pain, diarrhea, or bloody diarrhea. Complications can include inflammation and ulceration of the colon with tissue death or perforation, which may result in peritonitis. People affected may develop anemia due to prolonged gastric bleeding
Sappinia diploidea is a free-living amoeba species.
A amoebic liver abscess is a type of liver abscess caused by amebiasis. It is the involvement of liver tissue by trophozoites of the organism Entamoeba histolytica and of its abscess due to necrosis.
Sappinia is a genus of heterotrophic, lobose amoebae within the family Thecamoebidae. A defining feature of Sappinia, which separates it from its sister genus Thecamoeba, is the presence of two closely apposed nuclei with a central, flattened connection. Sappinia species have two life cycle stages: a trophozoite and a cyst. Up until 2015, only two species had been discovered, Sappinia pedata and Sappinia diploidea. Sequencing of the small subunit rRNA of a particular isolate from a sycamore tree revealed a new species, Sappinia platani.Sappinia species were once thought to be coprozoic, as the first strains were isolated from animal dung. More research has shown that they are typical free-living amoebae, and can be found worldwide in soil, plant litter, and standing decaying plants, as well as freshwater ponds. In 2001, the first and only case of human pathogenesis in Sappinia was confirmed. The patient was a non-immunocompromised 38-year-old male who presented signs of amoebic encephalitis and who patient made a full recovery after treatment with several antimicrobials. The CDC initially classified the causative agent as S. diploidea based on morphological characteristics, but in 2009, Qvarnstrom et al. used molecular data to confirm that the true causative agent was S. pedata.
Dehydroemetine is a synthetically produced antiprotozoal agent similar to emetine in its anti-amoebic properties and structure, but it produces fewer side effects. In the United States, it is manufactured by Roche.
An amoeba, often called an amoeboid, is a type of cell or unicellular organism which has the ability to alter its shape, primarily by extending and retracting pseudopods. Amoebae do not form a single taxonomic group; instead, they are found in every major lineage of eukaryotic organisms. Amoeboid cells occur not only among the protozoa, but also in fungi, algae, and animals.
Naegleria fowleri, colloquially known as a "brain-eating amoeba", is a species of the genus Naegleria, belonging to the phylum Percolozoa, which is technically not classified as true amoeba, but a shapeshifting amoeboflagellate excavate. It is a free-living, bacteria-eating microorganism that can be pathogenic, causing an extremely rare sudden, severe and usually fatal brain infection called naegleriasis or primary amoebic meningoencephalitis (PAM). This microorganism is typically found in bodies of warm freshwater, such as ponds, lakes, rivers, hot springs, warm water discharge from industrial or power plants, geothermal well water, poorly maintained or minimally chlorinated swimming pools, water heaters, soil, and pipes connected to tap water. It can be seen in either an amoeboid or temporary flagellate stage.