Mine workers served by drifts and adits are subject to occasional attacks of this disease, which is often fatal. It is caused by a micro-organism, the principal carrier of which is the sewer rat. If the skin is scratched, the germ can enter the bloodstream of the miner. 1604 Preventive measures include clearing up of all stores, food, and other waste to deprive the rats of food and of a systematic extermination by a pest control officer. Also known as Weil's disease.