The association between central nervous system (CNS) infections and epilepsy has not received adequate attention perhaps because of a declining trend in the incidence of many CNS infectious disorders in most of North America and Western Europe. From a global perspective, however, infectious disorders continue to arouse interest. Malaria (including cerebral malaria caused by Plasmodium falciparum) affects up to 600,000 children, of whom 100,000 die every year in sub-Saharan Africa. Outbreaks of viral encephalitis continue to be reported from different regions of the world, while Japanese B encephalitis remains highly endemic in much of Asia. Likewise, Taenia solium cysticercosis is endemic in Central and South America as well as parts of South and Southeast Asia. Recently, the infestation has been documented in large populations in Africa. Hence, while some of the traditional microbial pathogens are slowly disappearing, new foci of infections due to these organisms are being uncovered and novel pathogens continue to emerge.

The causal link between many CNS infectious disorders and epilepsy is well known. For other infectious disorders, such as malaria, the link has been appreciated only very recently. For still other disorders, for example, toxocariasis, the link remains controversial. Furthermore, it is not enough to demonstrate a causal association between various CNS infections and epilepsy. The underlying structural basis, course, and prognosis of epilepsy must also be clarified. In addition, the effects of antimicrobial treatment of the infectious disorders, and the effects of antiepileptic drugs on seizure outcome in this context, also need to be considered.

In 1996, there was a meeting of a subcommission of the International League Against Epilepsy at which CNS infections as a cause of epilepsy was discussed within the framework of epilepsy in tropical regions of the world. It was clear from that meeting that a review of further developments in our efforts to understand the association between CNS infections and epilepsy was required. Hence, a meeting of several experts in the fields of infectious disorders and epilepsy was organized at Chandigarh, India, in February 2007. The meeting focused on unremitting long-term seizure activity that occurs following CNS infections; acute symptomatic seizures were not discussed. The principal aims of the meeting were to review current knowledge about, and identify unanswered questions relating to the interface between CNS infections and epilepsy. Towards this end, the following specific questions were considered:

  • 1
    What is the risk attributable to infectious disorders with regard to the occurrence of epilepsy?
  • 2
    What are the structural correlates (determined from contemporary imaging studies) of epilepsy that occur as a remote complication of CNS infections?
  • 3
    What are the course, outcome, and prognosis of epilepsy following CNS infections?
  • 4
    In the specific context of chronic CNS infections, what is the effect of treatment of infectious disorder on the course and prognosis of the epileptic (seizure) disorder?
  • 5
    What is the effect of antiepileptic drug treatment on the course and outcome of the epileptic disorder?

This Epilepsia supplement is a product of that meeting. In the opening paper of this supplement, Singh and Prabhakar present an appraisal of epidemiological, microbiological, and epileptological principles that are necessary for the understanding of the link between CNS infections and epilepsy. Next, the associations between epilepsy and several CNS infectious disorders—including bacterial meningitis (Murthy and Prabhakar), viral encephalitis (Misra, Tan, and Kalita), cerebral malaria (Ngongou and Preux), T. solium cysticercosis and other selected helminthic infestations (Garcia and Modi), and human immunodeficiency virus infection (Satishchandra and Sinha)—are discussed by leading experts. In the two concluding papers, aspects of treatment of the infectious disorders as well as the epilepsy are considered (Singh and Prabhakar, Desai), with emphasis on the inter-relationship between the two. We hope that the supplement achieves what it was intended to do—provide a roadmap for future epidemiological and clinical research in the interface between CNS infections and epilepsy.

We are grateful to several pharmaceutical companies including Novartis India, Intas Pharmaceuticals, Sun Pharmaceuticals, and Torrent Pharmaceuticals, India, for support of the meeting upon which this supplement is based, and to Sanofi Aventis, India, for partial support of the supplement.