Introduction

Throughout history in the Indian Ocean World (IOW) diseases have, under certain distinctive geographical and climatic conditions, emerged and spread, generating a number of impacts on varying spatial scales. The IOW, a macro-region lying between latitudes 45°S and 45°N running from Eastern Africa through the Middle East, South and Southeast Asia to East Asia, encompasses tropical, sub-tropical, and temperate zones, major oceans, gulfs and rivers, islands, lakes and deserts, and the world’s highest mountain range (Map 1.1). It thus experiences major differences in temperature and rainfall, which are further affected by other environmental factors—the most significant of which is the monsoon system of winds and currents that governs the IOW littorals and seas north of about 12°S of the equator. In the northern hemisphere summer, the southwest monsoon dominates, bringing heavy rainfall to the Asian littoral, while in winter the