Outbreaks of Group B Meningococcal Disease - Florida, 1995 and 1997

Morbidity and Mortality Weekly Report, Oct 9, 1998

Since 1992, Neisseria meningitidis serogroup B strains have caused several community- and school-based outbreaks in the United States (1). Response to such outbreaks is difficult because no serogroup B vaccine is licensed currently for use in the United States, and mass chemoprophylaxis has been evaluated only in restricted settings (2,3). This report describes the use of mass prophylaxis to control outbreaks of serogroup B meningococcal disease in Florida in two unusual settings: a hotel resort and a nursing home.

Miami-Dade County

During July-August 1995, the Miami-Dade County Health Department was notified of one probable and four laboratory-confirmed cases of serogroup B meningococcal disease among children vacationing at a local resort area. All of the cases occurred among county residents who either stayed at or visited Hotel A. One child died.

The first reported case was in a guest at Hotel A who developed a fever on July 8. On July 9, symptoms developed in a sister and brother staying at Hotel B who had visited Hotel A to play with other children. The sister died shortly after admission to a local hospital; N. meningitidis serogroup B was isolated from blood cultures. Her brother was admitted with fever, vomiting, leg pain, and a petechial rash, and gram negative diplococci were observed in the cerebrospinal fluid (CSF). However, cultures were negative for N. meningitidis.

For the investigation, a hotel-related confirmed case was defined as isolation of N. meningitidis serogroup B from the blood or CSF of a person with classic symptoms of meningitis who was staying at or visiting hotel A. A presumptive case was defined as detection of gram-negative diplococci in specimens from a normally sterile site (blood and CSF) in a person with classic symptoms who had close contact with a confirmed case-patient.

Investigators noted overcrowding at hotel A, where some rooms had as many as 12 residents. An estimated 730 persons stayed or worked at hotels A and B during the week before onset of symptoms in the first two cases (attack rate: 274 per 100,000 population). The Advisory Committee on Immunization Practices defines an outbreak of serogroup C meningococcal disease as three or more confirmed or probable cases occurring during a period of approximately 3 months in persons with a common affiliation but no close contact, resulting in a primary disease attack rate of at least 10 cases per 100,000 persons (4).

After consultation with epidemiologists at the Florida Department of Health and CDC, county health officials offered prophylaxis on site to all guests and employees at both hotels. Over a 2-day period, 480 persons (66% of the targeted group) received the recommended rifampin dosage. The hotel swimming pool, the site of organized activities for children, was closed.

Approximately 5 weeks after the first cluster of cases was identified, a case was diagnosed in a 17-year-old who provided child care at hotel A during the days before onset of symptoms. A secondary case (occurring at least 24 hours after onset in the primary case) was diagnosed in a child who had been in this 17-year-old's care and who had resided at the hotel since June. The child and her family had received prophylaxis at the time of the first meningitis cluster. The county again offered prophylaxis to all guests and employees at hotel A. No further cases were identified among visitors to the resort area.

Skilled Nursing Facility

On December 5, 1997, the Florida Department of Health was notified of a laboratory-confirmed case of N. meningitidis in a resident of a 104-bed skilled nursing facility. Within 5 days, two additional laboratory-confirmed cases were diagnosed from the facility; all three cases were serogroup B.

For the investigation, a suspected case of meningococcal disease was defined as clinical diagnosis of meningococcal disease in a nursing home resident or staff member; a case was confirmed by isolation of N. meningitidis from blood or CSF.

A nurse had been hospitalized on December 1 with confusion and fever following 2 weeks of influenza-like symptoms. His CSF contained elevated protein, decreased glucose, and a mononuclear cell count of 7500 per cc. Specimens for culture were not obtained until 3 hours after antibiotics were started and were negative for bacterial pathogens.

On December 2, a 90-year-old patient in the wing where the staff nurse was assigned was hospitalized with a fever of 104 F (40 C) and vomiting. She died the following day. Blood cultures were positive for N. meningitidis. On December 5, a 56-year-old nursing assistant who had cared for the first confirmed case-patient was hospitalized after abrupt onset of fever and stiff neck; her CSF was positive for N. meningitidis

On December 5, the Florida Department of Health recommended chemoprophylaxis for all patients and staff. However, the facility had consulted a community physician who recommended administration of prophylaxis to all persons who had visited the facility during the previous 14 days, nasopharyngeal swabs for culturing of all patients and staff, and closure of the facility to all visitors.