The mumps outbreak surfaced in Iowa is spreading, infecting other U.S. states. Iowa's Department of Public Health recorded at least 605 cases of mumps, most of them among university students, between December 2005 and April 13 of this year. The normal number of cases found in the state yearly is 5. Authorities are investigating dozens of cases of infection in Illinois, Kansas, Minnesota, Missouri, Nebraska and Wisconsin. The infection is present especially among people aged between 18 and 25 years, on college campuses, where the living conditions make an ideal breeding ground for the virus. While the source of the outbreak remains unknown, health officials are worried that the very contagious virus may have been spread by 2 mumps-infected patients traveling on commercial flights. The US Centers for Disease Control and Prevention are now trying to notify passengers who flew between March 26 and April 2 of the possible risk. Mumps is a viral disease with symptoms similar to flu and is recognizable by the swelling of glands at the base of the jaw. Mumps can cause sometimes complications like inflammation of the ovaries or breasts in women and the testicles in men, in rare cases even leading to meningitis, miscarriage, sterility or deafness. The disease can be transmitted through coughing, sneezing or sharing cups and eating utensils. Scientists have identified the mumps strain as genotype G, the same genotype circulating in the United Kingdom. The outbreak in the U.K. started in 2004 and involved over 70,000 cases.