Enzyme-linked immunosorbent assay for the detection of antibodies to the sheep scab mite Psoroptes ovis.

An enzyme-linked immunosorbent assay has been shown to detect antibodies in the circulation of sheep infected with Psoroptes ovis. Strong positive reactions were obtained from 19 sheep with four-month-old infections. No cross reaction was observed with sera obtained from sheep infected with either Fasciola hepatica, Nematodirus battus, Ostertagia circumcincta or Damalinia ovis.

Flumethrin: a non-stripping pyrethroid dip for the control of sheep scab.

Flumethrin, a synthetic pyrethroid, used in the laboratory as a sheep dip (Bayticol) at a concentration of 55 ppm, eradicated sheep scab from 30 infested sheep and provided protection against infestation for at least seven weeks. Similar results with at least five weeks protection were obtained on monitor sheep dipped under field conditions with flocks of 525 and 870 sheep. The dip was prepared and replenished with 66 ppm flumethrin and the concentration did not strip.

History, biology and control of sheep scab.

Sheep scab is one of the oldest known diseases of sheep. It is caused by either of the mange mites Psoroptes ovis (Fig. 1 and cover) or Sarcoptes scabiei. P. ovis causes irritation so intense that sheep become preoccupied with scratching, cease to feed and rapidly become emaciated. It should be eradicated on welfare grounds alone (Fig. 2).

Some observations on the biology and control of the sheep scab mite Psoroptes ovis (Hering) in Britain.

Sheep scab was eradicated from Britain in 1952 but reappeared in 1973. The host specificity of the sheep scab mite is discussed; sheep are the only reservoir of the disease in Britain. Control is by single dipping in the approved acaricides, HCH, diazinon or propetamphos. Acaricides are approved only if the minimum use rate (Maintenance level) will give at least 4 weeks' protection. The method of testing is described. Traditionally, compulsory dipping has been in the winter when the disease is most active. Although the mites were originally thought to enter a latent phase during the summer, new observations indicate that there is little difference between their summer and winter behaviour. In Britain, dipping is now compulsory in both the summer and winter.

The efficacy of showers for control of ectoparasites of sheep.

Ectoparasites of sheep in Britain include the tick Ixodes ricinus, the blowfly, Lucilia sericata, the ked, Melophagus ovinus and the lice, Damalinia ovis and Linognathus ovillus. The most important ectoparasite, however, is the mite Psoroptes communis ovis which causes sheep scab. This notifiable disease was eradicated from Britain in 1952 but was reported again in 1973. The control of ectoparasites depends largely on the efficient application of insecticide to the fleece and skin. Plunge dipping in a bath is generally regarded as the most efficient method and is compulsory for the control of sheep scab but it is not always the most convenient. After the eradication of sheep scab in 1952 plunge dipping was no longer compulsory and jetting, spraying and showering techniques were then employed for the other ectoparasites.