Hi and thank for the question, the decrease in sensitivity could could arise form a vast majority of sources. A fungal infection left untreated could lead to a transient decrease in sensitivity. Other causes like leprosy and nerve lesions in this could really be very less probable. Visiting a dermatologist would be of much help in ascertaining the cause. A physical examination and a few exams will make things clearer and facilitate appropriate and more specific management schemes. i therefore suggest you book an appointment with your nearest dermatologist. Thanks for using health care magic and hope this helps, best regards, Luchuo, MD.