This is surprising to most parents who expect infections, such as the cold and flu, to occur in the winter. Among the viruses that can commonly cause infections in the summer include enteroviruses (stomach bugs), parainfluenza (respiratory bugs) and poliovirus (polio). Although more common in winter, it is also possible to catch a rhinovirus -- the common cold -- in the summer. Adenovirus infections, which can cause a variety of symptoms, also are more common in the late winter and spring, but can occur in the early summer.