A cold and fever will not necessarily cause an enlarged spleen. Firstly, a cold and fever can cause a variety of symptoms such as runny nose and weakness, but not necessarily an enlarged spleen. On the other hand, there are many factors that can cause an enlarged spleen, including infectious and non-infectious factors, and infectious diseases that cause a cold and fever are only some of them and may not be the main cause. If there is both a fever and an enlarged spleen, you should be examined as soon as possible to confirm the presence of an infection.