I do not know if Pierre Arents was the photographer who created these magnificent portraits of leprosy or if he only burned and printed the copper plates from the negatives. I am inclined to believe that credit for the photographs must be given not just to Arents or to Dr. Leloir who conceived the project, but also to the caretakers in the leprosariums of Norway and Italy who helped to dress and prepare their patients for the camera. This was the collective effort of empathic men and women possessing the gift to recognize and be humbled by a quiet dignity forged in monstrous suffering. 
These haunting sublime photogravures illustrated the 1886 publication Traité Pratique Et Théorique De La Lèpre, a French medical text on Leperosy. The title page of the text identifies the accompanied ‘Atlas’ containing 22 ‘planches originales en chromolithographie et en héliogravure.’ No photographer is identified.
 http://www.artandmedicine.com/biblio/authors/french/Leloir.html cited 02/21/23