48- Nematode control in farm situations. Evolution of control, and the challenge of resistance. A practitioner¹s view

MEJIA, M; LICOFF, N; LAZARO, L; LACAU-MENGIDO, I

Calgary, Canada

Congreso; 22nd WAAVP conference; 2009

World Association for the Advancement of Veterinary Parasitology

Parasite control has evolved over the last 25 years in Argentina. In the 80s, productivity promoted nematode control and many systems were developed: Tactic systems based on fixed treatments, Systematic (falsely called “0” risk) models proposed to cut the cycle, and Integrated control as the most rational. Ivermectin appeared with a great impact in production by the “apparent” control of worms. In the 90s, epidemiological-based models proposed the “Strategic” system based in the effect of some few strategic treatments on larval availability and the consequent infection. Then, a pronounced decrease in drug prices also took place, and it became easier and cheaper to deworm with long acting drugs, than to sample, pay for assessment, or think: every-30-days deworming was established. In this decade resistance appeared and control systems proposed by scientists which were more rational, with rotation of drugs and less use of them, and an epidemiological base for the control were promoted. But farmers continue to deworm without assessment, and long acting products are invading the market. Resistance is not known, nor believed to exist in many cases.We will discuss the real problems a vet has when he/she has to deal with parasites, resistance, farmers, publicity, drug quality, and production system variability. We will show many examples of everyday problematic decisions, and try to give a “practical” view on EPG interpretation in relation with resistance; on reduction tests in farm situations, and the “real”? significance of those results. We will also analyze the evolution of resistance in some farms and the concept of practical reversion.