In: Focus on Multiple Sclerosis Research ISBN 1-59033-985-1 Editor: Frank Columbus, p. 163-195 © 2004 Nova Biomedical Books. Chapter 10 A META-ANALYSIS OF HUMAN HERPES VIRUS 6 AND CHLAMYDOPHILA PNEUNONIAE IN MULTIPLE SCLEROSIS J. Gutiérrez, M. García, F. Fernández School of Medicine, Granada, Spain; M. Guerrero, University Hospital, Granada O. Fernández, V.E. Fernández, G. Luque University Hospital; Málaga J. D. de Luna University of Granada ABSTRACT Background: An increasing number of studies have related two infectious agents, human herpes virus type 6 (HHV-6) and Chlamydophila pneumoniae, with multiple sclerosis (MS). The situation, however, remains unclear. Aim: To undertake a meta-analysis of studies published until year 2002. Methods: A search across electronic databases using key words relating relapsing remitting MS and infectious agents supposedly involved. Strict selection criteria were applied. Results: Sixteen articles fulfilled the methodological selection criteria. Statistical analysis showed that HHV-6 was related with MS by detection of DNA in serum and antibodies in serum and cerebro-spinal fluid, but not with DNA in cerebrospinal fluid or white cells. C. pneumoniae was related with MS by detection of DNA and antibodies and recovery of bacteria in cerebrospinal fluid, but not with antibodies in serum. Conclusion: No study was found with a sufficient number of patients and samples, prospective, and comparative versus healthy controls and patients with other neurological diseases, which employed a combination of several microbiological techniques in the same subjects and samples, and then correlated the results with disease activity.