When MS-DOS closes the file, the virus reverses these actions, reinfecting the file. By following a few guidelines, the risk of contracting a virus can be minimized and chances of full recovery increased. First and most important is the purchase of a virus scanning program. These can be purchased at any store that sells software or computers. These programs are designed to help guard against viruses and remove and clean up after any virus infection.
Most current programs do an excellent job of finding viruses.
This is important as well. Viruses change often, and companies should have a good method for updating the software such as downloading from the web or frequent disk mailings. These should be included in the cost of the program or be available at a very modest cost. In addition to any automated settings in a program, several other good habits are important. Scan all floppies that you receive from someone else, purchase, or use in any other computer.