Venereology is a branch of medicine dealing with the study and treatment of sexually transmitted diseases. It includes the study of HIV infection. A medical doctor specializing in venereology is called a venereologist. In some countries the specialty is combined with dermatology. The venereal diseases include bacterial, viral, fungal, and parasitic infections. Some of the important diseases are HIV infection, syphilis, gonorrhea, candidiasis, herpes simplex, human papillomavirus infection, and genital scabies.