Stages of HIV Infection

Original Editor - Cindy John-Chu

Top Contributors - Cindy John-Chu, Kim Jackson and Chloe Waller  

Introduction[edit | edit source]

Human Immunodeficiency Virus (HIV) is a virus that attacks the human immune system (especially the CD4 and T cells) and when left untreated, leads to Acquired Immune Deficiency Syndrome (AIDS). Immunosuppression (the reduced ability to fight infections and other diseases) is determined by laboratory measurements of CD4+ T cells and plasma HIV viral load[1]. As of the end of 2021, it was estimated that 38.4 million people are living with HIV, with two thirds of that population in the African region[2].

Modes of Infection/ How does Infection Occur in the Body?[edit | edit source]

Infection occurs when one comes into contact with body fluids of infected persons.

Stages of HIV Infection[edit | edit source]

In low resource settings there is not always the possibility to measure immunosuppression via laboratory testing, so the World Health Organisation (WHO) developed a staging system based on a patients clinical features. There is 4 progressive stages and categorisation results from the patient displaying at least one clinical condition in the stage's criteria. The clinical phases are linked to the progression of the infection and laboratory markers.[3]

The four stages are:[4][3]

Stage One: Patients in this category are usually asymptomatic, or have swelling of lymph nodes for more than 6 months.

Stage Two: Also known as a mildly symptomatic stage. It is characterised by an unexplained weight loss of less than 10% of total body weight; recurrent respiratory infections such as: sinusitis, bronchitis, otitis media, and pharyngitis; an array of dermatological conditions including: recurrent oral ulceration, papular pruritus eruptions and fungal nail infections.

Stage Three: Also known as the moderately symptomatic stage of the infection. The following characterises this stage: weight loss of greater than 10% of the total body weight, unexplained diarrhoea occurring for more than one month, pulmonary tuberculosis; bacterial infections like: pneumonia, pyelonephritis, empyema, pyomyositis, meningitis and bacteremia; mucocutaneous conditions such as:recurrent oral candida sis, gingivitis or periodontics.

Stage Four: At this stage, a clinical diagnosis of Acquired Immune Deficiency Syndrome (AIDS) is made when the following clinical findings are made: HIV wasting syndrome, pneumocystis pneumonia, recurrent severe or radiological bacterial pneumonia, extrapulmonary tuberculosis, HIV encephalopathy, CNS toxoplasmosis, oesophageal candidiasis and Kaposi's sarcoma.

Resources[edit | edit source]

References[edit | edit source]

  1. Simon V, Ho DD, Karim QA. HIV/AIDS epidemiology, pathogenesis, prevention, and treatment. The Lancet. 2006 Aug 5;368(9534):489-504.
  2. World Health Organisation. HIV/AIDS. Available from: (Last accessed 06/12/2022).
  3. 3.0 3.1 Weiner JL, Kovarik CL. The WHO Clinical Staging System for HIV/AIDS. Virtual Mentor 2010; 12 (3): 202-206
  4. World Health Organisation. Consolidated Guidelines on the Use of Antiretroviral Drugs for Treating and Preventing HIV Infection: Recommendations for a Public Health Approach. [Internet] 2nd edition. Geneva; 2016. Available from: (Last accessed 06/12/2022)