A method for sheep scab control by applying selective treatment based on flock serology

Area of Science:

• Veterinary Parasitology
• Sheep Health Management
• Acaricide Resistance

Background:

• Sheep scab, caused by Psoroptes ovis, is a significant disease impacting sheep health and productivity.
• Current control relies on acaricidal dips or avermectins, with state-regulated treatment protocols in Switzerland.
• Untreated sheep act as reservoirs, posing a risk for re-infestation of treated flocks.

Purpose of the Study:

• To evaluate the efficacy of a targeted serological testing and treatment strategy for sheep scab control.
• To assess the reduction in mite prevalence and reliance on broad-spectrum parasiticides.
• To investigate the potential for reducing avermectin use and mitigating resistance development.

Main Methods:

• Serological testing of sheep flocks in the Canton of Schwyz, Switzerland, from 2001 to 2003.
• Treatment of seropositive flocks with doramectin (an avermectin).
• Monitoring of seropositive flock and animal proportions over the study period.

Main Results:

• A significant decrease in seropositive flocks from 5.8% in 2001 to 2.2% in 2003.
• A corresponding reduction in seropositive animals from 6.3% to 2.1% over the same period.
• The majority of remaining seropositivity in 2003 was attributed to Chorioptes spp., indicating a decline in Psoroptes ovis.

Conclusions:

• Targeted chemo-metaphylaxis based on serological testing is effective in controlling sheep scab.
• This strategy can reduce the overall use of endectocides and ectocides.
• Reduced parasiticid use benefits environmental health, minimizes human exposure, and combats anthelmintic resistance.