Infectious diseases are caused when disease-causing agents invade the body tissue of an organism. These agents multiply and release toxins that cause infections within the body and the host tissues react against them. Infectious diseases are also known as transmissible or communicable diseases as they are caused by the biological pathogens which are easily transmitted to others. The infectious agents that cause these diseases include viruses, fungi, bacteria, parasites and arthropods. The most common symptoms of such diseases are fatigue, skin rashes, coughing, and fever. Some common infectious diseases are anthrax, chickenpox, chlamydia, cholera, Lyme disease, measles, etc. Medications such as antibiotics, antifungals, antivirals and antihelminthics, are used for the treatment of infectious diseases. This book consists of contributions made by international experts. It provides comprehensive insights into infectious diseases. The extensive content of this book provides the readers with a thorough understanding of the subject.