Risk factors for carriage of meningococcus in the Los Angeles County men's jail system.

Ten cases of meningococcal meningitis in the Los Angeles County men's jail system in 1986 were the first known reported cases in this population. New cases have continued into 1990. Nineteen of 21 symptomatic cases identified by serogroup from the men's jail occurring through 1988 had serogroup C. The prevalence of meningococcal carriage and potential risk factors were studied in 1988 among 150 men booked to enter the jail, 350 inmates being released, and 100 jail staff. The prevalence of meningococcal carriage among releases, bookings, and staff were 25.4%, 18.7%, and 5.0%, respectively. Among releases, imprisonment longer than a threshold of 28 days increased carriage of serogroup C 10.0 times (95% confidence interval (CI) 4.6-21.6). Among bookings, household crowding increased serogroup C carriage 8.2 times (95% CI 1.5-45.3). Direct and passive smoking at home increased carriage of any serogroup 5.2 (95% CI 1.2-47.5) and 2.5 (95% CI 1.1-5.8) times, respectively. Feasible potential interventions include banning smoking in the jail and immunization with quadrivalent meningococcal vaccine of booked men sentenced for one month or more.