H.I.V./ AIDS is caused by the H.I.V. virus, the human immunodeficiency virus, an R.N.A. virus that replicates by reverse transcription. H.I.V. causes AIDS (acquired immunodeficiency syndrome). In low-income countries, H.I.V. AIDS is still among the top 10 causes of death. In 2020 approximately 38 million people were living with H.I.V. worldwide (two-thirds in the African region). In 2020 there were around 700 thousand deaths from H.I.V. AIDS worldwide, with about one point five million newly diagnosed cases of H.I.V.. There is a high prevalence of H.I.V. in Africa. There are multiple countries in Africa with a 20 to 30% prevalence of H.I.V..
In the United States, over one million individuals live with H.I.V.. In the United States in 2019, men who have sex with men accounted for 66% of new H.I.V. infections. Racial groups and high-risk populations have a much higher H.I.V./ AIDS burden in the United States than the general population, particularly among African-American/black populations, men who have sex with men, and individuals that use intravenous drugs. There has been an increased prevalence of H.I.V. in the United States due to the effective treatment of H.I.V., significantly prolonging life. The number of deaths from H.I.V./ AIDS in the United States has been trending down, which started with the availability of antiretroviral therapy. Vertical transmission rates have also decreased. Vertical transmission is the passing of H.I.V. from the mother to the newborn upon birth.
The H.I.V. AIDS epidemic started around 1981, around the time of the historical publication of five cases of pneumocystis pneumonia among homosexual men in Los Angeles, published in the C.D.C. M.M.W.R.. Traditional high-risk populations for H.I.V. AIDS are men who have sex with men, hemophilia patients receiving transfusion (this is no longer a significant risk in the U.S. due to screening of blood donors for H.I.V., previously transfusion clotting factors were from pooled donors), and intravenous drug use. There is still a stigma of H.I.V. AIDS, which worsens health disparities and decreases the diagnosis rate among those infected with H.I.V.. H.I.V. has a very long incubation period - a long time from initial H.I.V. infection until diagnosed with H.I.V. or AIDS if the diagnosis is prompted by an AIDS-defining illness. Highly active antiretroviral therapy became available in the mid-1990s. H.I.V. one is the predominant H.I.V. infection that causes AIDS. The first case of H.I.V. one is thought to be a patient from Zaire, Africa, in 1959, now the Democratic Republic of Congo in Central Africa. The origin of the H.I.V. virus is believed to come from zoonotic infection originating in nonhuman primates, possibly from hunters collecting bushmeat in Central Africa. In the early 80s, H.I.V. one was isolated, and HIV-two was isolated in 1985. H.I.V. two is less common than H.I.V. one and less problematic. However, H.I.V. two can still cause AIDS. H.I.V. transmission is by blood (mainly blood transfusions (some countries still do not screen blood donors for H.I.V.), the sharing of I.V. drug needles, or from a needle stick in the hospital setting) or sexual contact. Vertical transmission from mother to newborn upon birth is also a mode of H.I.V. transmission. H.I.V. infects CD4 positive cells, macrophages, and dendritic cells. Dendritic cells are antigen-presenting cells in the skin, linings of the nose, lungs, intestines, and stomach. As well as T cells positive for CD4. Without treatment, H.I.V. AIDS is eventually fatal in almost all cases. Untreated, H.I.V. has a very high case-fatality rate. With effective treatment, the case-fatality rate for H.I.V. is low. In 2017 the cause-specific mortality rate was five per one thousand persons diagnosed with H.I.V..
Initial signs and symptoms of H.I.V. infection are non-specific, flu-like symptoms, headache, sore throat, and fever. Many people are asymptomatic upon initial infection with H.I.V. As the immune system weakens with the progression to AIDS, many signs and symptoms may be seen, weight loss, fever, lymphadenopathy, and a variety of other AIDS-defining illnesses. As defined by the C.D.C., there are many AIDS-defining illnesses. Some of the AIDS-defining illnesses are:
AIDS is diagnosed by the presence of an opportunistic/ AIDS-defining illness or a CD4 count less than 200. Surveillance of H.I.V./ AIDS is done in the United States. The National H.I.V. Behavioral Surveillance System works to monitor three high-risk groups, men who have sex with men, IV drug users, and high-risk heterosexual males and females. H.I.V. infection is reported as an H.I.V. diagnosis and not an incidence due to the often-long lag time in diagnosis from time of infection. All people should be screened for H.I.V. during pregnancy and treated if found to be H.I.V. positive. C-sections and avoiding breastfeeding are helpful to reduce vertical transmission to newborns. Strategies for reducing H.I.V. transmission are elective circumcision of males, pre-exposure prophylaxis for high-risk populations, consistent condom use, and needle exchange programs. There are over 20 licensed drugs in the United States to treat H.I.V.. H.I.V. treatment does not cure but puts the H.I.V. virus into latency. If treatment is stopped, the H.I.V. virus will reactivate. Lifelong treatment to suppress viral replication is recommended. Basically, an H.I.V. diagnosis equals lifelong treatment to prevent transmission and reduce morbidity and mortality. There is no waiting period to start H.I.V. treatment if someone is found to be H.I.V. positive. The typical starting medications for H.I.V. are an integrase inhibitor plus two nucleoside/nucleotide reverse transcriptase inhibitors. Prophylactic antibiotics are recommended if the CD4 count is less than 200. The usual prophylactic antibiotic is T.M.P.-S.M.X. to prevent pneumocystis pneumonia.
Pregnant persons should be screened with each pregnancy. Screening is recommended by the United States Preventive Services Task Force for all adolescents and adults 15 to 65 years of age at least once as part of usual clinical care and more frequently for high-risk individuals depending on their level of risk (Grade A recommendation). The C.D.C. recommends that high-risk individuals be screened at least yearly. There is a waiting period following initial H.I.V. infection until a positive screening assay can be obtained. There is typically a high viral load/ high viremia during this window period. Depending on the assay used, the window period can be as short as two weeks. Nucleic acid tests have the shortest window period. There are also combination tests that detect the p twenty-four antigen and antibodies to H.I.V., as well as antibody tests. Antibody tests have the longest window period. The first screening antibody tests had a window period of around three months. There is also an eclipse period, which is the time around initial H.I.V. infection when there is no diagnostic test that can diagnosis H.I.V.. Children under 18 months cannot be tested with typical serological screening tests. They need to be diagnosed with virological testing. To increase the number of H.I.V. screening tests administered, the Opt-Out approach for H.I.V. screening was developed. The patient is notified that an H.I.V. test was ordered and will be administered during the visit unless the patient does not desire one to be performed. The patient has the choice to opt-out of H.I.V. testing if they want to. There is no vaccine for H.I.V.
References:
Jones J, Kelley C, Sullivan PS, Curran JW. The Epidemiology and Prevention of HIV and AIDS. In: Boulton ML, Wallace RB. eds. Maxcy-Rosenau-Last Public Health & Preventive Medicine, 16e. McGraw Hill; 2022. Accessed January 04, 2022.