Nematodes activity against

Ivermectin is active against two significant phyla of animal parasite the Nemathehninthes or nematodes (roundworms) and the Arthropoda (insects, ticks, and mites). Ivermectin is inactive against platyhehninthes (flukes and tapeworms). 

Ivermectin has an extremely broad spectmm of antinematodal activity in a variety of domestic animals. Indeed, among the many nematodes against which it has been tested, none has been found that is not affected by ivermectin during at least one stage of the life cycle. In all but a few instances the dmg is highly active against both immature and mature worms (19). 

Ivermectin is used in cattle, sheep and horses at 0.2 mg/kg swine at 0.3 mg/kg dogs at 0.006 mg/kg and man at 0.05 —0.2 mg/kg. It is effective against parasitic nematodes, gmbs, Hce, mites, ticks, and bots. Ivermectin is not active against tapeworms, flatworms, bacteria, or fungi. 

Siddiqui lA, D Haas, S Heb (2005) Extracellular protease of Pseudomonas fluorescens CHAO, a biocontrol factor with activity against the root-knot nematode Meloidogyne incognita. Appl Environ Microbiol 71 5646-5649. 

Glazer I, Novan A. Activity and persistence of entomoparasitic nematodes tested against Heliothis armigera. J Econ Entom. 1990 83 1795-1800. 

Tests using helminth infections in a variety of laboratory animals soon revealed that the avermectins had activity against a variety of nematodes but lacked activity toward cestodes and trema-todes. During the course of testing in a number of other assays, they were found active against the flour beetle, Tribolium confusum (14). This activity against arthropods was confirmed in mice infected with larvae of the bot fly, Cuterebra fontinella. 

This dual activity against both nematode and arthropod parasites of animals was an unexpected bonus from a screen for anthelmintic agents. The reason for this broad activity lies in their mode of action. They act by interfering with y-aminobutyric acid (GABA) mediated neurotransmission. When treated with avermectin, the nematode Ascaris suum becomes paralyzed although it retains normal muscle tone (17). Picrotoxin, an antagonist of GABA, can reverse the effect of avermectin on neurotransmission vitro. 

The avermectins were initially detected in a program in which thousands of microbial fermentation products were tested in mice for activity against the nematode, Nematospiroides dubius. 

The initial objective of the search was an anthelmintic with properties radically different from those of known anthelmintics. What was found was an anthelmintic whose properties were indeed markedly different — not only in terms of chemical structure and efficacy against helminths, but also in the extension of the potential utility of the class to the control of arthropod parasites of animals. Further, the compounds turned out to have striking activity against a variety of free-living and plant-parasitic nematodes and arthropods — and so it has come about that a new livestock anthelmintic has become an agenda item in this symposium on agricultural pesticides. 

The Japanese people live in a delicate micr0eCOsystem that can be easily polluted by industrial chemical accidents and the use of persistent agricultural chemicals. An intensive scientific effort has led to the isolation and identification of biodegradable natural products for potential use in agriculture. These include microbial metabolites that have activity against plants, microorganisms, nematodes, and insects. 

Several benzimidazoles are in use for the treatment of helminthic infections. Three of these, mebendazole, thiabendazole and albendazole, are described in this section. They have a broad range of activity against many nematode and cestode parasites, including cutaneous larva migrans, trichinosis, disseminated strongyloidiasis, and visceral larva migrans. A fourth, triclabendazole, is considered as the drug of choice for Easciola hepatica therapy. 

Albendazole has a broad spectrum of activity against intestinal nematodes and cestodes, as well as the fiver flukes Opisthorchis sinensis, Opisthorchis viverrini, and Clonorchis sinensis It also has been used successfully against Giardia lambfia. Albendazole is an effective treatment of hydatid cyst disease (echinococcosis), especially... 

Metrifonate (9.121), an organophosphate compound, is a low-cost antihelminthic used to treat Schistosoma hematobium infections. The drug appears to alter cholinesterase activity in the nematode, temporarily paralysing the adult worm and causing the worm to die. Because of its activity against the cholinesterase enzyme, this drug has also been evaluated as a treatment for Alzheimer s disease. 

Levamisole possesses a broad spectrum of activity against lung and gut nematodes, but it has no activity against cestodes, trematodes, and arthropods. It is commonly used in swine, nonlactating dairy cattle, beef cattle, sheep, goats, and poultry in die forms of pour-on, bolus, drench, feed additive, or injectable... 

Oxyclozanide possesses activity against only adult flukes, but at elevated dosage levels some activity against the later parenchyma stages (flukes of more than 4 weeks of age), may be obtained. In sheep and cattle, recommended oral dosages are 10-15 mg/kg bw. It is frequently combined with levamisole or oxibc-ndazole for combined treatment of gastrointestinal nematodes and liver fluke infections. 

Macrocyclic lactones are active against a variety of nematodes but lack activity toward cestodes and trematodes. They are also active against a wide variety of insects and other arthropods, including mites, ticks, and lice. Since these compounds encompass activity against both endo- and ectoparasites, they are also called ectendocides. 

Abamectin is a specific mixture of two components avermectin Bi and avermectin Bib. Both of these components possess a double bond between C22 and C23 and differ by a methylene group in the side-chain substituents on C25. The mixture containing not less than 80% avermectin Bu and not more than 20% avermectin B is known as abamectin. Abamectin has a broad spectrum of activity against nematodes, but is primarily used in agriculture as an acaricide and insecticide (46). 

Ivermectin (IVER) is a drug with a broad spectrum of activity against gastrointestinal nematodes and lung parasites in food-producing animals. In the EU, the maximum residue levels set for IVER in the liver of sheep, pigs, and cattle are 15,15, and 100 tg/kg, respectively (217). The use of automated SPE equipment was described for IVER HPLC analysis in animal liver samples. This automated system, ASPEC, was used for the SPE purification step in order to provide more efficient and faster sample preparation. Some tests were performed to obtain recovery and repeatability data. The mean recovery for spiked samples was more than 90% in the concentration range of 7.5-30 tg/kg. 

The end of patent cover for most of the modern anthelmintics means that market prices have fallen and therefore funds are lower for investment in research into animal health by pharmaceutical companies. As it is the animal health market that drives any search for anti-parasitic drugs by the pharmaceutical companies, few companies are now looking for modern anti-nematodal drugs and the market size for drugs that kill trematodes and cestodes are such that a search for new drugs cannot be financially justified. Unless a novel anthelmintic that kills nematodes happens to have activity against trematodes or cestodes, it is unlikely that new drugs will become available... 

Many plant constituents and metabolites have been investigated for activity against plant-parasitic nematodes. The conditions under which compounds are effective against nematodes vary with the compounds (Ferris and Zheng, 1999 Zasada and Ferris, 2004). These active compounds, or precursors of active compounds, can often be applied to soil as organic amendments, or refined and developed as biopesticide compounds. 

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