Mumps Outbreaks on University Campuses -- Illinois, Wisconsin, South Dakota

A total of 480 cases of mumps (epidemic parotitis) were reported among students attending 16 universities and colleges in three states where active surveillance was undertaken during the 1986-87 academic year. This report summarizes the investigations of these outbreaks. Illinois

One hundred and eighty-three cases of clinically diagnosed mumps* were reported from 10 colleges and universities in Illinois during the 1986-87 school year. Detailed investigations, including interviews with patients, were conducted for three of these outbreaks, which totaled 123 cases. Four cases were serologically confirmed at the state laboratory by a fourfold or greater rise in hemagglutination inhibition antibody titer of sera taken during the acute and convalescent stages of illness.

Western Illinois University, Macomb: From September 17, 1986, to February 25, 1987, 37 cases of parotitis were identified at Western Illinois University (WIU), which has a full-time undergraduate student enrollment of 8,912 (Figure 1). The attack rate among males (5.9/1,000) was 2.7 times higher than the attack rate among females (2.2/1,000) (95 confidence interval (CI) = 1.3, 5.5). In addition, the attack rate among students living in on-campus residence halls ( 6.5/1,000) was 8 times the attack rate among those in other forms of housing (0.8/1,000) (CI = 3.0, 21.6). Of the 36 patients for whom school class was known, attack rates were inversely related to the class level. These rates were 7.0/1,000 for freshmen, 4.2/1,000 for sophomores, 1.6/1,000 for juniors, and 1.5/1,000 for seniors (chi-square for trend, p less than0.001). A similar trend was observed for the subset of students living in dormitory housing (p less than0.03).

Bradley University, Peoria: From January 22 to May 3, 1987, 55 cases of mumps were reported from Bradley University, which has a full-time undergraduate student enrollment of 3,328 (Figure 1). Interview data were available on 45 students. The attack rate among males (17.6/1,000) was not significantly different from the attack rate among females (15.1/1,000). The attack rate for dormitory residents was 18.8/1,000; for fraternity and sorority residents, it was 12.8/1,000; and for residents of other off-campus housing, it was 14.8/1,000. As at WIU, underclasspersons were the most likely to be affected, with rates of 18.5/1,000 for freshmen and 25.0/1,000 for sophomores, compared with rates of 10.0/1,000 for juniors and 9.3/1,000 for seniors (p less than0.006).

Millikin University, Decatur: From February 18 to May 15, 1987, 31 cases were reported from Millikin University, which has a full-time undergraduate student enrollment of 1,377 (Figure 1). Interview data were available for 20 ill students. The attack rates among males (20.6/1,000) and females (24.1/1,000) were not significantly different. In-state residents, who comprised 92 of the enrollment, had an attack rate of 11.0/1,000. The attack rate among out-of-state residents was 54.5/1,000 (relative risk = 4.9; CI = 2.1, 11.6). Residence-specific attack rates were 21.8/1,000 for dorm itory residents, 11.2/1,000 for fraternity and sorority residents, and 5.3/1,000 for residents of other off-campus housing (p = 0.06). Freshmen had the highest risk of mumps, with an attack rate of 39.0/1,000, compared with 11.3/1,000 for sophomores and 5.8/1,000 for juniors (p =0.001). No cases were reported among seniors.

In the three Illinois university outbreaks, students missed an average of 6.5 days of classes. The 102 ill students who were interviewed at least 2 weeks after onset of parotitis averaged 2.3 health-care visits each. This included visits to emergency rooms and private physicians, but not hospitalizations. Six students were hospitalized for a total of 32 days, an average of 5 days each. Seventeen percent of the 102 patients reported severe headache, often associated with other meningeal signs and symptoms. Nineteen percent (12) of the 64 male patients reported orchitis, as evidenced by testicular pain and swelling. Three of these patients required hospitalization.

Control efforts at each of the universities focused on isolating ill students from the rest of the student body. This was usually accomplished by sending students to their parents' homes. Publicity about the outbreaks was disseminated through university publications and health services. Students who were uncertain of their immunity to mumps were encouraged to obtain mumps vaccine. WIU provided combined measles-mumps-rubella vaccine for a nominal fee and gave 46 doses over the course of the outbreak. Bradley University provided single antigen mumps vaccine free of charge and gave 152 doses. Millikin University directed students to the nearby county health department to receive vaccine, but none took advantage of the opportunity. By the end of the school year, however, Millikin University had established a policy requiring proof of immunity to mumps for matriculation in the fall of 1987. The Illinois legislature has recently mandated that both public and private colleges and universities require all students to present proof of protection against mumps as well as five other vaccine-preventable diseases. Proof of immunity to mumps can consist of documentation of either physician-diagnosed mumps or vaccination with live mumps vaccine at 12 months of age or older.

South Dakota

A total of 119 cases of mumps was reported from five universities and colleges in South Dakota during the 1986-87 school year. The University of South Dakota at Vermillion, which has a full-time student enrollment of 5,511, reported 94 cases. A 22-year-old Iowa woman with onset of illness on December 18, 1986, had the first reported case. The last reported case occurred on May 1, 1987, 1 week prior to the end of classes for the academic year. Although follow-up study to determine complications was not complete, epididymo-orchitis was reported for three (5) of the 56 affected males. No other complications were reported. Forty-four (47) of the 94 students lacked documentation of either prior mumps vaccination or previous mumps illness. Comparison data for students who did not become ill were not available.

Mumps was also reported from four other colleges and universities in South Dakota: South Dakota State University (SDSU) in Brookings (16 cases), Northern State College (five cases), Augustana College (three cases), and Sioux Falls College (one case). Complications were reported for two (12.5) of the 16 affected students at SDSU. One was a female student with meningoencephalitis and pancreatitis; the other, a male student with epididymo-orchitis. Neither student had a history of receiving mumps vaccine. No complications were reported from the remaining three colleges reporting mumps cases. Wisconsin

The largest outbreak occurred at Marquette University in Milwaukee, where 178 cases of mumps were reported between February 4 and May 14, 1987. The university has about 8,700 full-time undergraduate students, 50 of whom are from out-of- state. The outbreak peaked in April but continued into June. Mumps virus was isolated from 15 patients. One hundred (60) of the 168 patients for whom data on gender were available were male. The median age was 20 years. Although there was no systematic assessment of complications, physicians at the student health service were aware of at least six cases (6) of orchitis among affected males. These physicians were not aware of any students who developed meningoencephalitis or required hospitalization. The outbreak was publicized through university and local news media. Measles-mumps-rubella vaccine was offered to students through the student health service free of charge, and 239 doses were administered during the outbreak. Reported by: K Caspall, McDonough County Health Dept; C Jennings, W Moran, M Andreasen, D Yeagle, R March, Immunization Program, BJ Francis, MD, State Epidemiologist, Illinois Dept of Public Health. L Schaefer, G Rhyne, Immunization Program, KA Senger, State Epidemiologist, South Dakota State Dept of Health. H Nichamin, MD, Milwaukee City Health Dept; C Leutzinger, Immunization Program, JP Davis, MD, State Epidemiologist, Wisconsin Dept of Health & Social Svcs. Div of Field Svcs, Epidemiology Program Office; Div of Immunization, Center for Prevention Svcs, CDC.

Editorial Note

Editorial Note: In general, the epidemiologic findings reported in the Illinois investigations were in keeping with observations in similar settings where there are aggregations of children and young adults in close contact. These settings include military barracks, boarding schools, and other institutions. Males and females are generally affected with equal frequency. Since preliminary data do not suggest any difference by gender in rates of mumps vaccination, the difference in attack rates for males and females at WIU was probably due to unknown differences by gender in the likelihood of exposure to mumps virus at this university. At WIU, residence in a dormitory was found to be a risk factor, presumably because of the increased potential for exposure to mumps virus in a dormitory setting. This increased potential could be due either to more confined living conditions or simply to close contact with greater numbers of contagious persons.

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