The transmission of meningococcal infection: a mathematical study

The most common type of bacterial meningitis in the developed countries is caused by Neisseria meningitidis bacteria, which cause meningococcal meningitis. Case fatality rate can be between 3% and 10% in developed countries and as high as 20% in African countries. During epidemics in sub- Saharan countries, the so-called meningitis belt, the case fatality rate can peak to 70% or higher. Some people who have bacterial meningitis experience some form of after effects: epilepsy, damaged eyesight, hearing loss, brain damage. There is no immunity after infection. Approximately on average 10% of the population at any time carry the germs for days, weeks, or months. Carriers can infect other individuals by close contacts, even though they do not become ill themselves. An age-structured mathematical model is formulated that enables the understanding of the dynamics of the infection transmission. The model is used to study the conditions for the stability of the disease-free steady state (which imply extinction of the disease) and the existence of an endemic state (which leads to persistence of the disease in the population). The results of the model are applied to identify the contribution of the carriers to the transmission of the disease. Final epidemiological conclusions are given.  2003 Elsevier Inc. All rights reserved