METHODS: IMD cases reported to the Chicago Department of Public Health (CDPH) and DuPage County Health Department were investigated to obtain risk factor information and to identify close contacts for antimicrobial prophylaxis. Case isolates were characterized by serogroup, pulsed-field gel electrophoresis (PFGE), and multi-locus sequence type (MLST) at the Centers for Disease Control and Prevention Meningitis Laboratory. Cases were cross-referenced in HIV and sexually transmitted infection (STI) surveillance databases. A vaccination campaign was launched targeting MSM in Chicago. Federally funded meningococcal conjugate vaccine (MCV4) was distributed to health care partners with large MSM and HIV-infected patient populations and to pharmacies to minimize cost barriers to vaccination. Recipients reported number of doses administered weekly to CDPH.
RESULTS: Seven cases of IMD including one fatality were reported during May–June, 2015. All case isolates were serogroup C and indistinguishable by PFGE and MLST. Case characteristics included median age of 39 years (range, 25–54 years), African American race (6), HIV co-infection (5) with median CD4 count of 116 (range, 67-369), history of or newly diagnosed syphilis (4), and history of gonorrhea (1). Risk factors also included anonymous sex (5), use of “hook-up” apps to identify sexual partners (7), and exchange of sex for money or drugs (1). By December 7, CDPH distributed 16, 655 MCV4 doses to 79 partner sites. Of 12,483 doses administered, 831 were second doses for HIV-positive individuals. CDPH directly administered 3,530 doses at pop-up vaccination clinics coordinated with public events. Outreach targeting at-risk groups through digital apps and other social media was performed, and >60 community-based organizations were engaged to promote prevention messages through social networks.
CONCLUSIONS: Outbreak case characteristics suggest a core group of MSM at heightened risk for IMD and linked through social networks. African American MSM and MSM living with HIV were disproportionately affected. Behaviors that increase risk for transmission of meningococcal disease need to be defined and effectiveness of vaccination among HIV-infected individuals assessed. Participation of community healthcare providers and community-based organizations amplified the reach of the vaccination campaign substantially. Further evaluation of the effectiveness of social networking technologies for targeting high-risk populations is planned.