Chemotherapy of Nematode Infections of Veterinary Importance, with Special Reference to Drug Resistance

Abstract

Publisher Summary The historical succession of one drug class after another has resulted in part from sequential improvement in drug characteristics (spectrum, safety, convenience), but also in part from the emergence of drug resistance. The phenomenon of resistance, so characteristic of the treatment of infectious diseases in general, is a prominent feature of the new era in antinematodal therapy. Anthelmintic use may vary to some extent in various parts of the world, but it rests largely on a common set of chemical compounds. An aspect of the older drugs is the development of new delivery technology. Administration of the injectable product gives high efficacy against many nematode and arthropod parasites, and these are disucssed in the chapter. The drug is active against gastrointestinal and pulmonary nematodes, against immature as well as mature worms, and against inhibited fourth-stage larvae. The susceptible arthropods include ticks, lice, mites, and grubs. Drug resistance is a heritable reduction in the sensitivity of a parasite population to the action of a drug, the reduction being expressed as a decrease in the frequency of individual parasites affected by exposure to the drug. Drug resistance generally results from decreased drug uptake, increased metabolism of the drug, or changes at the drug-receptor site.