 In 1863 he published "Skin Diseases of Parasitic Origin", in which he was the first physician in the UK to create a thorough study of the pathology and causes of dermatophytosis (ringworm).At this time, he decided to specialise in dermatology rather than obstetrics.In 1864, Fox developed an interest in tropical dermatology with a trip to India with the Earl of Hopetoun.