Cacao swollen shoot virus (CSSV) is a plant pathogenic virus of the family "Caulimoviridae" that primarily infects cacao trees. It decreases cacao yield within the first year of infection, and usually kills the tree within a few years. Symptoms vary by strain, but leaf discoloration, stem/root swelling, and die-back generally occur. The virus is transmitted from tree to tree by mealybug vectors. It was first discovered in Ghana in 1936, and is currently endemic in Togo, Ghana and Nigeria. Over 200 million trees have already been claimed by this disease, which has prompted Ghana to launch the most ambitious and costly eradication effort of any country in the world against a viral plant disease.