Human Immunodeficiency Virus and Gastrointestinal Tract

Acquired immunodeficiency syndrome (AIDS) has been a devastating pandemic since the late 20th century, caused by the human immunodeficiency virus (HIV). HIV-1 is the most prevalent type worldwide. HIV-2 is less prevalent and less pathogenic, found principally in western Africa. Globally, HIV continues to be a major public health problem. The availability of highly active antiretroviral therapy has reduced the number of complications and their severity, while prolonging life expectancy, but it is not yet a cure. Because of the prolongation of life, many chronic complications of the disease, such as coinfection with hepatitis B/C, are increased.

The mode of infection is variable depending on the geographic area. Blood, breast milk, semen, and vaginal secretions can transmit the disease. In the United States as well as other developed nations, the most frequent mode of transmission is having unprotected anal or vaginal sex with an infected individual. According to the Centers for Disease Control and Prevention (CDC), about 67% of people diagnosed with HIV in 2014 in the United States were gay and bisexual men. Globally speaking, other more common risks include sharing contaminated needles, blood transfusions, and medical procedures involving unsterile cutting or piercing and organ transplantation in unsafe environments.

The three stages of HIV infection are as follows. The first stage, Acute HIV, develops within 2 to 4 weeks of acquiring infection. The symptoms include fever, headache, rash, fatigue, swollen lymph nodes, malaise, and ulceration in the mouth, esophagus, or genitals. In the chronic stage (asymptomatic HIV), the virus continues to multiply at low levels, but the patient is infective. Without highly active retroviral therapy (HAART), chronic HIV infection progresses to AIDS in 10 or more years. With the evolution of the disease, HIV infection reduces the number of CD4 cells in the body (normal 500 to 1600 cell/mm ³ ). When the number falls below 200 cells/mm ³ , the HIV infection has progressed to AIDS.

With the availability of HAART since 1996, the clinical spectrum has changed. HAART is composed of a combination of three to four drugs. The individual components of HAART are reverse transcriptase inhibitors, protease inhibitors, and fusion inhibitors. The components of HAART attack the viral life cycle at different points. However, the prohibitive cost of HAART has excluded a large number of patients in developing nations from the benefits. These patients still develop the classic complications of HIV disease of the pre-HAART era.

IHAART produces a logarithmic fall in the circulating HIV load with appreciable increases in CD4 lymphocyte counts. A notable reduction of many complications is associated with identification of a few new complications often related to HAART. Currently the life-span of an HIV patient is about the same as someone who does not have HIV disease. A clinician practicing in a major metropolitan city in the United States with a large number of immigrants is still likely to observe the spectrum of HIV manifestations of both the pre-HAART as well as the post-HAART era.

The terms HIV and AIDS are interchangeably used in the following discussion.