A viral disease of European rabbits (Oryctolagus) and domestic rabbits, spread mainly by biting insects (mosquitoes and rabbit fleas) and characterized by edematous swellings of the skin, particularly on the head and anogenital area. The disease is caused by infection with myxoma virus, a pox virus, which occurs naturally in certain species of the genus Sylvilagus in North, Central, and South America. In these rabbits, infection results generally in localized, nonmalignant tumors that disappear in weeks or months.