Written by recognized authorities, this book summarizes significant advances in understanding the complexity of host genetic susceptibility. Substantial progress has been made over the last ten years in identifying why some people are particularly susceptible to specific infectious diseases. Extensive evidence has also been accumulated to reveal that host genes are important determinants of the outcome of infection for many common pathogens. Diseases covered include those of great public health inportance such as malaria and HIV, as well as those of current topical interest such as Creutzfeldt-Jakob disease.