The term 'SPREAD DISEASE TO' can be solved by the crossword solution INFECT, which is a 6-letter word. Infection is the process by which a pathogen, such as a virus, bacterium, or parasite, enters and multiplies within the body, causing disease. Infectious diseases are caused by microorganisms such as viruses, bacteria, fungi, and parasites, which can be spread from person to person through direct contact, contaminated food or water, or airborne particles.