Diphtheria Posted on 7th November 201524th July 2021 by ThePD (The Project Definition) Diphtheria is an acute infectious upper respiratory tract disease that causes the inflammation of the mucous membrane. Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on LinkedIn (Opens in new window) Related Posted in HSE and tagged health. ThePD (The Project Definition) ThePD has been developing the Preferred Project Definitions based on the actual project execution and operation experiences and knowledge with the Project Language, and sharing with you daily basis.