If an animal has not had ringworm they are more likely to be susceptible to it. Animals kept in the same pen with infected individuals are more likely to catch this fungus. If your sheep is kept in dark, damp, warm, and poorly ventilated areas your animal is more likely to become infected. Sheep in contact with cattle are more likely to get this disease. Washing lambs often will remove lanolin and normal bacteria thus causing a higher chance of susceptibility.
Flies can spread ringworm.
Nicks and cuts from shearing allow skin to become infected. The University of Nebraska Cooperative Extension NF91-29 gives great advice. The doctors are in. This page gives likely forms of transmission and how to stop it from affecting you. 15.html helps us diagnose and ringworm.