Targeted selective treatment (TST): A promising approach to combat anthelmintic resistance in farm animals
R Edith, TJ Harikrishnan and M Balagangatharathilagar
Anthelmintic resistance is rising as a big threat for the control of gastrointestinal parasitism in farm animal production. Many strategies have been suggested to slow down the development of anthelmintic resistance and to maintain anthelmintic efficacy. One such strategy is Targeted Selective Therapy (TST) in which animals that require anthelmintic treatment alone is treated. Several methods have been suggested to selectively treat with anthelmintics. First method is based on parasitological indicator in which egg per gram (EPG) of faeces can be used to determine the existence and severity of helminth infection. Second method is based on pathophysiological indicators such as body weight and body condition score, anaemia, diarrhoea and plasma pepsinogen levels in animals with helminthic infection. In this method FAMACHA system is practical and proven farm method for anaemia evaluation in animals with hematophagous parasites. Dag score and diarrhoea score (DISCO) are based on the diarrhoea in helminth infected animals. Third method is based on the performance based indicators like milk production and live weight gain. Recently, five point check system in which eye, nose, jaw, back and tail are examined as evidence of parasitism and the selected animals are treated. In TST, only the needy animals alone are treated thereby reducing the cost of treatment, drug residues in milk and meat and spread of drug resistant genes.