Acquired immunodeficiency syndrome (AIDS) is a sexually transmitted disease (STD) caused by the human immunodeficiency virus (HIV). HIV primarily damages CD4⁺ cells, such as T lymphocytes and monocyte-macrophages, leading to progressive immune deficiency. This results in severe opportunistic infections and rare malignancies, ultimately causing death. AIDS is among the leading fatal infectious diseases in humans.

Associated Factors for Disease Onset

HIV is a retrovirus with RNA as its genetic material, classified into two types: HIV-1 and HIV-2. HIV-1 is the predominant subtype responsible for the global AIDS epidemic, while HIV-2 is mainly localized to West Africa. HIV most commonly enters the host through the mucosa of the anus or genitals. Populations at higher risk for HIV infection include those engaging in unprotected sexual behavior, individuals who inject drugs, recipients of contaminated blood products, and persons exposed to needlestick injuries.

Modes of Transmission

HIV can be present in the blood, semen, vaginal secretions, pleural fluid, peritoneal fluid, breast milk, and cerebrospinal fluid of infected individuals. Both AIDS patients and asymptomatic HIV carriers are infectious. The primary route of transmission is sexual contact, followed by bloodborne transmission and mother-to-child transmission. Pregnant individuals infected with HIV may transmit the virus to the fetus via the placenta or infect the newborn during vaginal delivery. Among cases of mother-to-child transmission, approximately 20% occur before 36 weeks of gestation, 50% occur within the few days leading up to delivery, 30% take place during labor, and postnatal transmission may occur through breastfeeding.

Effects on Mothers and Newborns

Immunosuppression during pregnancy can influence the course of HIV infection, accelerating the progression from the asymptomatic stage to AIDS and exacerbating the severity of AIDS and related syndromes. HIV can lead to adverse pregnancy outcomes, including miscarriage, preterm birth, stillbirth, low birth weight, and neonatal HIV infection. Without antiretroviral therapy (ART), the mother-to-child transmission rate of HIV is approximately 30%. This rate can be reduced to less than 2% with ART, obstetric interventions such as elective cesarean delivery at 38 weeks of gestation, and the avoidance of breastfeeding.

Clinical Manifestations

The progression from HIV infection to AIDS can be divided into three stages: acute HIV infection, asymptomatic HIV infection, and AIDS.

Acute HIV Infection

This stage typically occurs 1–2 weeks after exposure to HIV. Extensive viral replication and a sharp decline in CD4⁺ T lymphocytes occur, leading to HIV viremia and acute immune damage in some cases. The most common clinical manifestation is fever, which can be accompanied by fatigue, night sweats, sore throat, nausea, vomiting, diarrhea, rash, joint pain, lymphadenopathy, and neurological symptoms. Most patients experience mild symptoms that resolve spontaneously within 1–3 weeks.

Asymptomatic HIV Infection

This stage follows primary infection or the resolution of acute symptoms and can last from a few months to two decades, with an average duration of 8–10 years. Patients typically exhibit no clinical symptoms, although some may experience persistent lymphadenopathy for prolonged periods.

AIDS

Patients in this stage may present with fever, diarrhea, weight loss, generalized superficial lymphadenopathy, and various opportunistic infections (e.g., oral candidiasis, pneumocystis pneumonia, cytomegalovirus infection, herpesvirus infection, toxoplasmosis, cryptococcal meningitis, or active pulmonary tuberculosis) and malignancies (e.g., Kaposi's sarcoma and lymphoma). Neurological symptoms occur in approximately half of the patients.

Diagnosis and Differential Diagnosis

Diagnosis is made based on medical history, clinical manifestations, and laboratory tests. HIV screening is recommended for pregnant individuals during their first prenatal visit. Those with high-risk factors for HIV infection undergo a second screening before 36 weeks of gestation. Laboratory evaluations include the following:

Antibody Screening Tests

These include immunoagglutination tests, immunochromatography assays (ICA), immunofiltration assays (IFA), enzyme-linked immunosorbent assays (ELISA), chemiluminescent immunoassays (CLIA), and antigen-antibody combination assays.

Supplementary Tests

These include confirmatory antibody tests and nucleic acid tests. Confirmatory antibody tests include immunoblot assays, line immunoassays, immunochromatography assays, immunofiltration assays, and alternative tests under specific conditions. Nucleic acid tests include qualitative and quantitative HIV RNA testing.

Viral Load Testing

Viral load measurements provide data to determine the initiation of antiviral therapy, assess treatment efficacy, predict disease progression, and guide adjustments in treatment regimens. Viral load can also serve as a diagnostic indicator of HIV infection.

CD4⁺ T Lymphocyte Count

Flow cytometry is used to measure the number of CD4⁺ T lymphocytes.

Drug Resistance Testing

This provides information for selecting and adjusting antiretroviral therapy regimens.

A differential diagnosis is required to distinguish AIDS from other conditions such as syphilis, disseminated gonorrhea, and rash-inducing infections from Epstein-Barr virus or cytomegalovirus mononucleosis.

Treatment

There is currently no cure for AIDS, and treatment mainly involves antiviral medications and general supportive and symptomatic care.

Antiretroviral Therapy (ART)

ART is recommended for individuals diagnosed with HIV as early as possible after confirmation of infection. The preferred initial treatment regimen consists of two nucleoside reverse transcriptase inhibitors (NRTIs) as a backbone combined with a third agent. The third agent may be a non-nucleoside reverse transcriptase inhibitor (NNRTI), a boosted protease inhibitor (PI), an integrase strand transfer inhibitor (INSTI), or a single tablet regimen (STR).

Immunomodulatory Therapy

Immunomodulatory agents such as alpha interferon, interleukin-2, intravenous immunoglobulin (IVIG), granulocyte-macrophage colony-stimulating factor (GM-CSF), and granulocyte colony-stimulating factor (G-CSF) may be utilized.

Supportive and Symptomatic Care

Efforts to improve nutritional support, treat opportunistic infections, and address malignancies are important components of care.

Treatment During Pregnancy

The goal of treatment for HIV-positive pregnant individuals is to prevent vertical transmission and manage maternal HIV infection. Specific treatment regimens are determined based on ART treatment history, drug resistance, gestational age, HIV RNA load, and CD4⁺ T lymphocyte count. Pregnant individuals newly diagnosed with HIV infection during pregnancy are advised to promptly initiate ART and receive counseling and evaluation for prevention of mother-to-child transmission.

Three ART regimens are commonly utilized during pregnancy:

Regimen 1: Tenofovir disoproxil fumarate (TDF) + Lamivudine (3TC) + Lopinavir/Ritonavir (LPV/r)
Regimen 2: Tenofovir disoproxil fumarate (TDF) + Lamivudine (3TC) + Efavirenz (EFV)
Regimen 3: Zidovudine (AZT) + Lamivudine (3TC) + Lopinavir/Ritonavir (LPV/r)

Pregnant individuals on ART before conception can continue their existing treatment regimen if the viral load is less than 50 copies/ml. Otherwise, adjustments to the ART regimen may be required. Late pregnancy diagnosis of HIV infection (after 28 weeks) may involve initiating a more intensive regimen, such as TDF + 3TC + Emtricitabine (FTC) + an integrase inhibitor if available. For those with prior ART use but current cessation, drug resistance testing is advised to inform restarting ART based on treatment history and resistance results.

Management During Delivery

HIV infection is not in itself an indication for cesarean delivery. Pregnant individuals who began ART during the first or second trimester, are taking ART consistently, have no clinical symptoms of AIDS, or have a viral load <1,000 copies/ml late in pregnancy or in active labor are not generally recommended for cesarean delivery. Planned cesarean delivery at 38 weeks may be advised if the viral load is >1,000 copies/ml or unknown during labor, to reduce perinatal HIV transmission. Invasive procedures during labor (e.g., episiotomy, artificial rupture of membranes, fetal scalp sampling, use of vacuum extractors or forceps) are typically avoided to minimize fetal exposure to HIV. During labor, initial intravenous administration of Zidovudine at 2 mg/kg over one hour is recommended, followed by a continuous intravenous infusion of 1 mg/(kg·h) until delivery. Post-delivery care should include guidance on safe feeding practices. For mothers with detectable viral loads, breastfeeding is not routinely recommended. If breastfeeding is chosen, ART should be continued throughout the breastfeeding period, in alignment with the pregnancy regimen, and breastfeeding should be stopped at six months. Postpartum hemorrhage may be managed using oxytocin or prostaglandins. Ergot alkaloids, which can synergistically enhance vasoconstriction when combined with reverse transcriptase inhibitors or protease inhibitors, are generally avoided.

Follow-Up and Prevention

Patients initiating ART typically undergo follow-up within 1–2 weeks to assess understanding of the treatment regimen, monitor adverse reactions, evaluate adherence, and address prevention of transmission. Once clinical stability on ART is achieved, follow-up frequency can be reduced to every 3–6 months. Drug resistance testing is performed in cases of virologic failure.

Prevention remains central to addressing AIDS:

Public education campaigns are utilized to raise awareness about the dangers of HIV/AIDS and its modes of transmission.
Illicit drug use is targeted for eradication.
High-risk populations are encouraged to undergo HIV antibody testing. HIV-positive individuals are provided with education and follow-up to prevent further transmission, and testing of their sexual partners for HIV antibodies is advised where applicable.
Screening for HIV antibodies is conducted for blood donors before donation.
Healthcare-associated HIV infections are actively prevented.
Condom use as a means of preventing HIV transmission is widely promoted.
Steps are taken to prevent HIV infection among women of reproductive age and to avoid unintended pregnancies in HIV-infected women.
Prompt treatment is provided to pregnant individuals diagnosed with HIV infection.