An Infectious Diseases specialist is an Internal Medicine, or for children - a Pediatric, medical doctor with additional qualifications enabling specialization in the evaluation and management of infectious diseases of all types. This specialist commonly is consulted to assist in the treatment of infections with complicated courses such as AIDS, underlying diseases that predispose to unusual or severe infections, unclear diagnoses, and fevers of unknown origin. Infectious disease specialists may also have expertise in preventive medicine and travel medicine.