On the relationship between meningococcal transmission dynamics and disease: remarks on humoral immunity.

We consider a model for the transmission dynamics of Neisseria meningitidis which incorporates the humoral immunity hypothesis in an explicit way. The "humoral immunity" hypothesis states that individuals will experience significantly different risks of invasive disease depending on whether they are experiencing their first infection episode, or a subsequent one. The model is fitted to the Stonehouse-Danbury carriage data and to UK disease data. For serogroup C (B) the risk of disease during the first infection episode results to be 100 (400) times higher compared to subsequent ones. Moreover the best-fit corresponds to the situation where N. lactamica essentially always confers cross-protection.