The crossword solutions for the term 'Disease Heart' are MONO, which stands for Mononucleosis. Mononucleosis is a viral infection that is caused by the Epstein-Barr virus and is commonly referred to as the 'kissing disease'. Symptoms of mononucleosis include fever, sore throat, swollen lymph nodes, and fatigue. It is usually spread through saliva, so it is important to practice good hygiene and avoid sharing drinks or utensils with someone who has the virus.