CHICAGO — Cases of meningococcal disease are on the rise in Chicago, with seven confirmed cases that have resulted in two deaths in about two weeks, city public health officials said. The seven cases of the dangerous illness have been reported since Jan. 15, according to a Thursday Chicago Department of Public Health news release. The disease is spread through “direct contact with saliva” and usually requires close and lengthy contact to spread, according to the health department. Though less contagious than the common cold or flu, it’s a “very serious illness” that requires treatment, according to the department. For better protection, Illinois recommends children receive a vaccination at ages 11-12 and a booster dose at 16, according to the health department.