This is a much-needed new, systematic review and study aid on microbiology, immunology, and infectious disease, including AIDS, for medical students studying for the USMLE Step 1. Its structure and content accurately reflect the USMLE's present concentration on the virulence factors of microorganisms, the diseases they cause, and the treatment of those diseases. The book first covers the essentials of microbiology and virology, including the important organisms responsible for present-day disease, and the essentials of immunology and the immune system components that protect the human host from infection. It then reviews infectious disease and the way microbiology and virology are clinically integrated, and covers the pathogenesis, diagnosis, and treatment of today's common diseases. The book also provides detailed coverage of congenital immunologic disorders plus a full chapter on AIDS. Each chapter ends with a 20-question self-assessment section followed by detailed answers with explanations.