Cause

Evidence is overwhelming that Human Immunodeficiency virus (HIV) causes Acquired Immunodeficiency Syndrome (AIDS). HIV infects a number of cell types important to activating and sustaining an effective immune response. Chief among these cells are CD4 T-helper cells. "CD4 T cells play a central role in immune protection. They do so through their capacity to help B cells make antibodies, to induce macrophages to develop enhanced microbicidal activity, to recruit neutrophils, eosinophils, and basophils to sites of infection and inflammation, and, through their production of cytokines and chemokines, to orchestrate the full panoply of immune responses."• HIV replication destroys CD4 T-helper cells. Loss of CD4 T-helper cells reduces the body's ability to fight off infection by organisms which are ordinarily kept in check by a healthy immune system.

Scope

The CDC states:

• At the end of 2012, approximately 1.2 million persons aged 13 and older were living with HIV infection in the United States
• About, 156,300 (12.8%) Americans are unaware of their infection.
• The CDC estimates the incidence of HIV has remained stable at about 50,000 new HIV infections per year. Some groups are affected more than others. Men who have sex with men (MSM) continue to bear the greatest burden of HIV infection. Among races/ethnicities, African Americans continue to be disproportionately affected.

Instant Feedback:

Risk Factors

• Transfusion of blood products before 1986
• Unprotected sex with an infected partner
• Sharing infected needles or syringes
• Mother to child exposure during birth or breastfeeding
• Transfusion of blood products after 1986 - very rare
• Transplant of infected tissue - very rare
• Occupational exposure - very rare

Diagnosis

During the initial phase of HIV infection, viral replication increases dramatically, then declines to a steady state during the chronic asymptomatic phase of HIV illness. Many individuals have only minor symptoms initially. Others develop a flu-like illness within a month or two after exposure to the virus. Early HIV symptoms may be mistaken for another type of viral infection:

• Fever
• Headache
• Fatigue
• Enlarged lymph nodes in the neck and groin

HIV infection can be verified by a number of tests.

• Enzyme immunoassay detects HIV antibodies in blood, urine or oral fluid. Rapid tests can return results within 30 minutes.
• RNA tests detect HIV RNA. They can detect early HIV RNA before sufficient antibodies are produced for immunoassay.

A diagnosis of AIDS requires: HIV confirmation plus CD4 T cell count < 200 cells per cubic millimeter (200/mL) of blood or HIV confirmation plus an AIDS defining condition.

Symptoms of opportunistic infections common in people with AIDS may include:

• Fever
• Coughing and shortness of breath
• Difficulty or painful swallowing
• Neurological symptoms
  • Headaches
  • Neuropathy
  • Confusion
  • Memory loss
  • Vision loss
  • Loss of coordination
  • Coma

• Severe and persistent diarrhea
• Nausea, abdominal cramps, and vomiting
• Weight loss and extreme fatigue

Instant Feedback:
AIDS is diagnosed when an HIV (+) person has a CD4 T cell count of less than or equal to 200/mL or if they develop an AIDS defining illness.