HIV is a retrovirus that specifically targets CD4+ T lymphocytes and other cells of the immune system, replicating within and ultimately destroying these critical defenders against infection. The virus progressively weakens immune competence, creating vulnerability to opportunistic pathogens and malignancies. Acquired Immunodeficiency Syndrome (AIDS) represents the most advanced stage of HIV infection, characterized by severe immunodeficiency typically manifesting as either a CD4 cell count below 200 cells per microliter or the occurrence of AIDS-defining clinical conditions. The disease spectrum ranges from initial acute retroviral syndrome through prolonged clinical latency to end-stage immunodeficiency in the absence of effective treatment.
Disease Profile
HIV/AIDS
艾滋病
Human Immunodeficiency Virus (HIV) infection represents a retroviral attack on the immune system that, without intervention, progresses through defined stages to Acquired Immunodeficiency Syndrome (AIDS). The disease remains a global public health challenge despite advances in testing, prevention through pre-exposure prophylaxis, and treatment with antiretroviral therapy that can suppress viral replication to undetectable levels, effectively eliminating transmission risk. Surveillance emphasizes early diagnosis through rapid testing and CD4 count monitoring to guide clinical management and prevent disease progression.
HIV infection classically progresses through three stages: an acute retroviral syndrome characterized by influenza-like illness with fever, lymphadenopathy, rash, and mucocutaneous lesions occurring two to four weeks post-exposure; a clinical latency phase that may remain asymptomatic for years while gradually depleting CD4 cells; and AIDS, marked by severe immunodeficiency and opportunistic infections including pneumocystis pneumonia, esophageal candidiasis, tuberculosis, and certain malignancies. Without treatment, approximately half of infected individuals develop AIDS within a decade. The normal CD4 count range spans 500 to 1500 cells per microliter, with counts below 200 indicating advanced disease requiring intensive monitoring and preventive interventions.
HIV/AIDS constitutes a global pandemic affecting populations across all geographic regions, with transmission dynamics influenced by behavioral, social, and structural factors. The disease burden concentrates disproportionately among key populations engaging in specific risk behaviors, though the precise epidemiologic distribution varies by regional context and surveillance capacity. Advanced HIV disease, defined by WHO as CD4 count below 200 cells/mm³ or WHO stage 3-4 events in adults and adolescents, or any confirmed HIV infection in children under five years, represents a critical surveillance threshold for treatment prioritization and resource allocation.
HIV is transmitted through the exchange of specific body fluids from infected individuals, including blood, semen, vaginal secretions, and breast milk. Transmission occurs via sexual contact, significant exposure to infected blood or tissues, and vertical transmission from mother to child during pregnancy, delivery, or breastfeeding. The virus does not spread through casual contact such as kissing, hugging, sharing food or water, or exposure to saliva, tears, or urine in the absence of blood contamination. Individuals with sustained undetectable viral loads on antiretroviral therapy effectively cannot transmit HIV sexually, a principle communicated as Undetectable = Untransmittable.
Source-backed detail on specific high-risk groups is not yet available in the provided material, though WHO references behaviors and conditions that elevate HIV acquisition risk and recommends targeted prevention services for populations with increased vulnerability.
HIV prevention encompasses multiple evidence-based strategies including behavioral interventions, biomedical approaches, and structural supports. Pre-exposure prophylaxis (PrEP) provides antiretroviral medication to HIV-negative individuals at elevated acquisition risk, representing an additional prevention option recommended by WHO. Post-exposure prophylaxis and maternal antiretroviral therapy prevent vertical transmission. Consistent condom use, sterile injection practices, and harm reduction services address transmission routes. Critically, antiretroviral treatment of infected individuals achieving undetectable viral loads prevents sexual transmission, linking treatment access directly to prevention outcomes.
HIV surveillance operates through a framework emphasizing the 5Cs: consent, confidentiality, counselling, correct results, and connection to treatment and prevention services. Diagnosis employs rapid diagnostic tests detecting HIV antibodies, with confirmatory testing required for positive results. Clinical monitoring relies on CD4 cell counts to assess immune status and disease progression risk, alongside viral load measurements to evaluate treatment efficacy. Testing services should facilitate same-day results and immediate linkage to care, with treatment initiation recommended upon diagnosis regardless of clinical stage. Population-level surveillance tracks incidence, prevalence, and treatment coverage to guide resource allocation and program evaluation.
- B20-B24
- 1C62
Figure 1 | Full historical trajectories across all reporting countries.
Figure 2 | Year-over-year monthly comparison for seasonality and structural shifts.
Dataset Archive
Supplementary Data | Multi-country disease dataset
Machine-readable multi-country disease dataset (JSON/CSV) with source metadata.
Source Register
Official sources and update cadences used to construct the downloadable dataset.
China
Monthly notifiable infectious disease reports published by China CDC.
Official sourceChina
Official China public health bulletin and query portal.
Official sourceChina
Biomedical literature discovery feed used as supplementary context.
Official sourceJapan
Japan weekly infectious disease surveillance via NIID/JIHS.
Official source