Neisseria meningitidis is an important cause of bacterial sepsis and meningitis in children, with one third of cases occurring in children under two years of age. An important strategy for preventing meningococcal disease is the identification of modifiable risk factors. Fischer and associates attempted to identify risk factors associated with meningococcal disease.

The study included 129 patients infected with N. meningitidis and 274 age-matched control subjects. Patients or their guardians were interviewed about numerous environmental and activity factors. Questions in the interview referred to the month preceding the patient's illness.

Having a mother who smokes was the strongest independent risk factor for invasive meningococcal infection in children under 18 years of age. A dose-response effect was found between the number of packs the mother smoked per day and the child's risk for disease. After adjusting for all other significant exposures identified, 37 percent of all meningococcal infections in children could be attributed to maternal smoking. An increased number of smokers in the home also had a significant linear relationship with the risk of meningococcal disease.

Other factors found to be independently associated with a risk of meningococcal disease in children under age 18 included having a mother who did not graduate from high school, lacking a primary care physician and living in a household below the poverty level. These factors were not associated with a risk of meningococcal disease in adults. Among adults, the strongest independent risk factor for meningococcal disease was an underlying chronic illness.

The mechanism by which tobacco smoke increases the risk of meningococcal disease is not known. Mechanical effects on respiratory mucosa or functional effects on the immune system may be important.

The authors conclude that exposure to tobacco smoke is an independent risk factor for meningococcal disease in children. The demonstration of a dose-response relationship and the plausibility and reproducibility of these findings strengthen this association. Reductions in smoking, especially among mothers of young children, may decrease the incidence of meningococcal disease.