The symptoms you describe are those of mosaic virus. There are two common types that affect tomato: tobacco mosaic virus and cucumber mosaic virus. Tobacco mosaic virus may be present in cigar, pipe, or cigarette tobacco, and smokers may carry the virus on their hands. These viruses are also present in many common weeds, and aphids can spread them from plant to plant. There is no cure for mosaic viruses. Keep aphid populations under control by spraying with insecticidal soap or other insecticide. If you are a smoker, wash your hands thoroughly after smoking and before working in the garden. Remove weeds in and around the garden. If you notice infected plants, remove and destroy them to prevent spread to healthy ones.