The human immunodeficiency virus (HIV) attacks the immune system, weakening the body’s surveillance and defense systems against infections and some cancers. As the virus destroys and impairs immune cell function, the infected person’s immune system gradually becomes defective. Immune function is usually measured by CD4 cell counts. The immune deficiency causes the body to become increasingly vulnerable to a large number of infections and diseases that the body could have fought off if the immune system had been intact.
Acquired immunodeficiency syndrome (AIDS) is the most advanced stage of HIV infection and can develop between 2 and 15 years after infection, depending on the individual infected. AIDS is defined as the presence of certain cancers, infections or other serious clinical manifestations.
Signs and symptoms
Symptoms of HIV infection depend on the stage of infection. People with HIV tend to be most infectious in the first few months, but many do not become aware of the status of their infection until later in life. During the first few weeks of initial infection, people may have no symptoms or may experience flu-like illness symptoms such as fever, headache, rash or sore throat.
As the infection gradually weakens the body’s immune system, other signs and symptoms, such as swollen lymph nodes, weight loss, fever, diarrhea and cough, may develop. If left untreated, serious diseases such as tuberculosis, cryptococcal meningitis and cancers such as lymphoma and Kaposi’s sarcoma may also occur.
Transmission
HIV can be transmitted by exchange of many body fluids such as blood, breast milk, semen, and vaginal secretions with an infected person. General daily contact such as kissing, hugging, shaking hands or using each other’s personal belongings, sharing meals or drinking water will not cause a person to acquire infection.
Risk factors
Some of the high-risk behaviors and situations in which individuals can become infected with HIV are
Having unprotected anal or cunnilingus intercourse.
Having been infected with another sexually transmitted disease, such as syphilis, herpes, chlamydia, gonorrhea, and bacterial vaginitis
Sharing HIV-contaminated needles, syringes and other injection equipment and drug injection solutions when injecting medications
Receiving unsafe injections, blood transfusions, and inadequately sterilized medical procedures for cutting or puncturing.
Inadvertent needle-stick injuries by health personnel, etc.
Diagnosis
HIV testing indicates infection status by checking for the presence of HIV antibodies and HIVp24 antigen in the blood. To fight foreign pathogens, the body’s immune system produces antibodies. Most people develop antibodies within 28 days of HIV infection and there is usually a 3 to 6 week “window period” during which the body is still producing HIV antibodies, but these antibodies are not yet detectable.
This initial period of infection is the most infectious, but HIV can be transmitted during all periods of infection. If there is a possibility that someone has recently been exposed to HIV, a retest should be performed in 6 weeks to confirm the test results. This allows sufficient time for the infected person to develop antibodies.
Testing and counseling
HIV testing should be voluntary. People have the right to refuse testing, and this should be recognized. Mandatory or coerced testing by health care providers, administration, or partners or family members is unacceptable because it tramples on good public health practices and violates human rights.
Some countries have adopted or are considering self-testing as an additional option. HIV self-testing is a procedure in which people collect specimens privately when they want to know their HIV status, perform the test and interpret the results. HIV self-testing is not a definitive diagnosis; it is an HIV screening test.
All testing and counseling services must include the five C’s recommended by WHO: informed consent, confidentiality, counseling, correct test results and linkage to care, treatment and other services.
Prevention
People can reduce their risk of HIV infection by limiting their exposure to risk factors. The main measures commonly used in combination to prevent HIV infection are
1. use of male and female condoms
Consistent and correct use of male or female condoms during vaginal or anal penetration can prevent sexually transmitted infections, including the transmission of HIV. Evidence shows that male latex condoms offer more than 85% protection against HIV and other sexually transmitted infections.
2. HIV and STI testing and counseling
It is strongly recommended that all people exposed to any risk factor be tested for HIV and other sexually transmitted infections so that they can know their infection status and access necessary prevention and treatment services without delay. WHO also recommends testing of partners or couples.
Tuberculosis is the most common infection among people living with HIV and is associated with approximately 25 percent of HIV-related deaths if not detected or treated. Early detection of TB and timely anti-TB and antiretroviral treatment can prevent these deaths. Simultaneous screening for HIV and TB is strongly recommended for all HIV-infected individuals.
3. Voluntary medical male circumcision
Voluntary male circumcision, when provided in a safe manner by trained health care workers, can reduce the risk of men acquiring HIV infection through heterosexual sex by approximately 60%. This is a key intervention in the context of a generalized epidemic where HIV prevalence is high and male circumcision rates are low.
4. Use of antiretroviral drugs for prevention
4.1 Antiretroviral drugs as prevention
A 2011 trial has demonstrated that when HIV-positive individuals are adherent to effective antiretroviral medication, the risk of passing the virus to their uninfected sexual partners is reduced by 96%. For couples in which one partner is HIV-positive and the other is negative, WHO recommends that the HIV-positive partner be provided with antiretroviral drugs regardless of the CD4 cell count.
4.2 Pre-exposure prophylaxis for HIV-negative partners
HIV pre-exposure prophylaxis (PEP) is the daily administration of antiretroviral drugs to HIV-uninfected individuals to prevent HIV infection. Studies have shown the effectiveness of pre-exposure prophylaxis in reducing HIV transmission among serodiscordant heterosexual couples (where one partner is infected and the other is not), men who have sex with men, transgender women, high-risk heterosexual couples, and people who inject drugs. WHO encourages countries to undertake projects to gain experience in the safe and effective implementation of pre-exposure prophylaxis.
In July 2014, WHO released the “Comprehensive Guidance on HIV Prevention, Diagnosis, Treatment and Care for Key Populations”, which recommends pre-exposure prophylaxis as an additional option for HIV prevention in the comprehensive HIV prevention series for men who have sex with men.
4.3 HIV post-exposure prophylaxis
Post-exposure prophylaxis refers to the use of antiretroviral drugs to prevent infection within 72 hours of exposure to HIV. Post-exposure prophylaxis includes counseling, emergency care and HIV testing, and administration of a 28-day regimen of antiretroviral drugs and follow-up care.
In a new supplement published in December 2014, WHO recommends that post-exposure prophylaxis be used for occupational and non-occupational exposures as well as for adults and children. This new recommendation proposes a simpler treatment regimen using antiretroviral drugs already in use in treatment. Implementation of the new guidelines will make it easier to prescribe, facilitate adherence to treatment, and increase completion rates for post-exposure prophylaxis to prevent HIV infection among health workers or people who are accidentally exposed to HIV, such as unprotected sexually exposed persons or those who have been sexually harassed.
5. Harm reduction for people who inject drugs
People who inject drugs can take precautions to prevent HIV infection by using sterile injection equipment, including needles and syringes, for each injection. A comprehensive package of HIV prevention and treatment measures includes
Needle and syringe planning.
Opioid substitution therapy and other evidence-based drug dependence treatment approaches for opioid-dependent users.
HIV testing and counseling.
HIV treatment and care.
Access to condoms.
Management of sexually transmitted infections, tuberculosis, and viral hepatitis.
6. Elimination of mother-to-child transmission of HIV
Transmission of HIV from an HIV-positive mother to her baby during pregnancy, delivery or breastfeeding is called vertical transmission or mother-to-child transmission. Without any intervention during these stages, the rate of HIV transmission from mother to child ranges from 15% to 45%. Mother-to-child transmission can be almost completely prevented if antiretroviral drugs are provided to the mother and infant throughout the period when infection can occur.
WHO recommends a PMTCT option that includes providing antiretroviral drugs to mothers and infants during pregnancy, delivery and the postpartum period and providing lifelong treatment to HIV-positive pregnant women, regardless of their CD4 count status.
In 2014, an estimated 73% [68%-79%] of the 1.5 million [1.3-1.6 million] pregnant women living with HIV globally received effective antiretroviral drugs to avoid transmission of the virus to their children.
Treatment
HIV can be suppressed with combination antiretroviral therapy consisting of three or more antiretroviral drugs. Although antiretroviral therapy cannot cure HIV infection, it can control viral replication in the body and boost the body’s immune system, restoring its ability to fight infection. With antiretroviral therapy, people living with HIV can lead healthy and productive lives.
By the end of 2014, about 14.9 million people living with HIV were receiving antiretroviral treatment worldwide. About 823,000 of them were children.
In 2014, there was a significant increase in the number of people on ART globally, with an increase of 1.9 million people in a single year.
The World Health Organization recommendation is that the timing of initial antiretroviral therapy is when the CD4 cell count of an HIV-infected person falls to or less than 500 cells/mL. However, it is recommended that antiretroviral therapy be recommended for all serologically discordant couples with HIV, pregnant and lactating women with HIV, patients with tuberculosis in combination with AIDS, HIV-infected patients with hepatitis B infection in combination with severe chronic liver disease, and all children under 5 years of age with HIV, regardless of CD4 cell count results.