Technical Abstract: Environmental ecosystems and climate are closely linked and they affect animal and human diseases. We describe (1) the effect of ecology on vector-borne disease, (2) the role of ecology and global climate in disease forecasting, and (3) the potential use of forecasting to reduce impact and limit spread of vector-borne disease. Temperature plays a major role in the ability of Aedes aegypti to transmit dengue virus in Southeast Asia and possibly chikungunya virus in Africa. Rainfall affects the ability of Aedes and Culex species to transmit Rift Valley fever (RVF) in sub-Saharan Africa. Modifications to environment such as the construction of a dam and development of rice irrigation projects affect the ability of Culex species to transmit RVF in Mauritania and Senegal. Links have been established between climate anomalies and infectious disease, particularly those transmitted by arthropods such as Murray Valley encephalitis, bluetongue, RVF, Ross River virus, dengue, malaria and chikungunya. The prediction of the 2006-2007 RVF in East Africa and subsequent observations of response activities can give us an insight about how disease forecasting based upon ecological conditions might help reduce the impact and spread of vector-borne diseases.