EE.UU – Prove efficacy of sequential treatment of Sea Lice

Merck Animal Health (known as MSD Animal Health outside the USA and Canada) presented the results of a study evaluating the benefits of treating salmon with SLICE® (emamectin benzoate) and then with hydrogen peroxide to reduce infestations

The study found that sequential treatment approach provided effective removal of existing infections of sea lice, and reduced the resettlement of a strain of sea lice resistant to emamectin benzoate, more effectively than treatment with hydrogen peroxide

“Sequential treatment with SLICE and hydrogen peroxide has been adopted by some veterinarians and producers to improve the fight against Sea Lice, particularly in populations of Sea Lice have shown resistance to treatments”, dijo Dafydd Morris, de Merck Animal Health. “We are pleased to present this important research to help growers optimize their approach to sequential treatment, and improve the effectiveness of its strategy of control and reduction of reinfection.”

In the study, Atlantic salmon of both sexes were exposed to infectious copepods resistant to emamectin benzoate population. After four weeks, the fish were randomly placed into 28 identical treatment tanks. On day 36, the fish were exposed to a second cohort of copepods, to ensure a population of Sea Lice different stages in fish.

The study showed that the efficacy against infection by sea lice was higher when hydrogen peroxide was administered 7 to 12 days after SLICE at a concentration of 1000 or 1400 ppm.

Sequential treatment with hydrogen peroxide SLICE seven days after had an efficacy of 86.1% in 1000 ppm and 1400 ppm 81.8%.

When hydrogen peroxide 12 days after the treatment was administered, the efficacy was 83% at 1000 ppm and 1400 ppm 91.2%.

The effectiveness of hydrogen peroxide in 1400 ppm without pretreatment with SLICE- was similar, 86% when administered on day 7 and 86.6% when administered on day 12.

The treatment groups receiving only SLICE experienced a limited reduction of infestation due to the resistance in the population of louse Mar.

In addition to determining the time and dosage most suitable peroxide after treatment with hydrogen SLICE, the study also sought to determine the effect of the product and residual hydrogen peroxide in reducing reinfection with a resistant strain of lice Sea.

The study found that treatment with hydrogen peroxide alone gave little or no benefit against reinfection of sea lice while sequential therapy showed similar efficacy to single treatment with SLICE, suggesting that hydrogen peroxide is ineffective residual. SLICE treatment, however, provided a 52.9% efficiency against reinfection 39 days after treatment.

SOURCE: Fis.com