Opportunistic infections (OIs) are defined as infections that are more frequent or more severe because of immune-suppression in HIV infected persons, and they are the major clinical manifestation of HIV patients. The natural history of HIV disease may be indirectly affected by the occurrence of opportunistic diseases, because HIV viral load increases in patients with acute opportunistic diseases. Survival in people infected with HIV has improved because of an increasingly powerful array of antiretroviral treatments, but neurological symptoms due to co morbidity conditions still remains public health important for HIV infected individuals. The most common opportunistic diseases in HIV patients are Candida esophagitis, Pneumocystis carinii pneumonia (PCP), disseminated Mycobacterium avium complex (MAC) infection, cytomegalovirus (CMV), Cryptococcus, kaposi sarcoma, herpes zoster, and tuberculosis. (NurilignAbebeMoges, Prevalence of Opportunistic Infections and Associated Factors among HIV Positive Patients taking Anti-Retroviral Therapy in Debre Markos Referral Hospital, Northwest Ethiopia). A journal is a periodical publication intended to further progress of science, usually by reporting new research. Most journals are highly specialized, although some of the oldest journals publish articles, reviews, editorials, short communications, letters, and scientific papers across a wide range of scientific fields. Journals contain articles that peer reviewed, in an attempt to ensure that articles meet the journal's standards of quality, and scientific validity. Each such journal article becomes part of the permanent scientific record.