. slope a 0.00 0.20 0.40 0.60 0.80 1. 00 1. 20 -1 5 -1 0 -5 0 5 10 15 Predictor variable, x2 Response variable, Pr(presence) Positive arg. b Logistic function negative slope 0.00 0.20 0.40 0.60 0.80 1. 00 1. 20 -1 5 -1 0 -5 0 5 10 15 Predictor. special issue of Advances in Parasitology, Volume 62, ‘ Global mapping of infectious diseases: methods, examples and emerging ap- plications’’ comprises 10 reviews and a DVD of global environmental and. Rollinson ADVANCES IN PARASITOLOGY VOL 62 ISSN: 006 5-3 08X $35.00 DOI: 10 .10 16/S006 5-3 08X(05)62 01 7-9 vii Guest Editors’ Preface It has been five years since an earlier special issue of Advances in Parasitology,