Phenotypic and Genotypic Analysis of Anthelmintic Resistance
A growing issue on a global scale is the emergence of helminth species and populations that are resistant to one or more anthelmintics. The majority of currently available anthelmintics used to control parasitic nematodes of cattle and sheep belong to only three main groups, benzimidazoles, imidazothiazoles and avermectins/milbemycins. The availability of reliable and precise techniques for its identification and monitoring is a critical component of the success of helminth control programs intended to prevent the spread of resistance in nematode populations. In vivo method like fecal egg count reduction test and in vitro methods such as egg hatch assays, larval motility test, larval development test and polymerase chain reaction (PCR) can be used for the detection of anthelmintic resistance although each has some reliability, repeatability, sensitivity, and ease of interpretation issues. The genetic basis of resistance to the majority of anthelmintics are still not well understood. Thanks to recent developments in high-throughput sequencing, it is now possible to define features such as drug resistance using genome-wide techniques. Keywords: Anthelmintics; Helminths; Resistance; Detection assays; Molecular diagnostics; Parasite control