Sexually transmitted infections (STIs) represent a global problem that has an impact on the reproductive and sexual health worldwide. The most common causative agents of the STIs are Chlamydia trachomatis, Neisseria (N.) gonorrhoea, Treponema pallidum and Trichomonas vaginalis. The World Health Organization estimated that these four main curable STIs cause approximately 498.9 million new cases worldwide in 2008. STIs can lead to serious consequences including health complications, chronic disease and high morbidity. Moreover, the economic costs associated with treatment of these diseases are immense. Furthermore, the resistance to antibiotics, in particular in N. gonorrhoea, has emerged in recent years. For these reasons, STIs represent a serious current public health problem. This book discusses several STI's including gonorrhoea, hepatitis C, and hepatitis B.