Sheep scab mite

Psoroptes ovis is a microscopic mite belonging to the Psoroptidae family, order Sarcoptiformes. It is important to note that this organism is not a plant pest, but a significant parasite of livestock, specifically causing a condition known as sheep scab (psoroptic mange) in sheep, cattle, and other domestic animals.

The biological cycle of the mite involves stages including egg, larva, protonymph, deutonymph, and adult. The entire life cycle occurs on the skin of the host. They feed on serous exudate produced by the host's skin in response to the mite's piercing action. Outside the host, the mites are relatively fragile and their survival depends heavily on environmental conditions like humidity and temperature.

The damage caused by these parasites is characterized by intense pruritus, inflammation, and the formation of crusts and scabs. The mites' saliva induces an allergic inflammatory response, which leads to hair or wool loss and skin thickening. In severe cases, the infected animals suffer from weight loss, reduced wool yield, and in the absence of treatment, secondary bacterial infections can be fatal.

Psoroptes ovis affects sheep, goats, and cattle primarily. The transmission occurs through direct contact with infested animals or indirectly via contaminated fencing, tools, or clothing of shepherds. High stocking densities and housing conditions during winter months significantly exacerbate the spread of the disease within the herd.

Control measures primarily involve stringent biosecurity protocols and the use of acaricidal agents. Effective management requires treating the entire flock or herd, even if only a few animals show symptoms. Systematic cleaning and disinfection of livestock housing facilities are essential to eliminate environmental sources of re-infestation. Modern veterinary treatments include injectable macrocyclic lactones and topical pour-on formulations.