Earliest sensation lost in leprosy is
The earliest manifestation of leprosy is the involvement of the cutaneous nerve, resulting in a loss of thermal sensation as the initial deficit and then evolving to involve other modalities like pain and touch. Sensory modalities subserved by larger fibers are lost in more advanced stages of the disease. Ref Harrison20th edition pg 1335
Thermal
Tactile
Pain
Vibration
Bacterial infections