A viral disease is an infectious disease caused by a virus. MEASLES is a highly contagious respiratory disease caused by a virus that can lead to serious complications such as pneumonia and encephalitis. HERPES is a viral infection caused by the HERPES simplex virus, which can cause painful blisters on the skin or mucous membranes. MUMPS is a contagious viral infection that primarily affects the salivary glands. The FLU is a contagious respiratory illness caused by influenza viruses. RABIES is a viral disease that affects the central nervous system and is usually transmitted through the bite of an infected animal. SHINGLES is a painful rash caused by the varicella-zoster virus, which is the same virus that causes chickenpox.