The human immunodeficiency virus is a retrovirus (Retroviridae family) that contains RNA and affects the immune system by attacking CD4+ T-lymphocytes, macrophages and dendritic cells. HIV attaches to the CD 4+ receptors expressed on the surface of these cells and enters their nucleus where with the help of the enzyme reverse transcriptase synthesizes DNA and replicates. Occurs viremia and the HIV spreads throughout the body.
There are two types of HIV distinguished – HIV-1 and HIV-2. HIV-1 is more common, whereas HIV-2 is mainly found in West Africa.
Prevalence of HIV
HIV is a global spread infection. According to the WHO, approximately 36,7 million people were infected at the end of 2016. Around half (16.7 million) of them were men and half (17.8 million) – women. 34.5 million were adults and 2.1 million – children younger than 15. About 30% of infected individuals are not aware of their condition.
More than 19.5 million people (53% of all, living with HIV) were receiving antiretroviral therapy as for December 2016.
According to the 2015 Global burden of Disease Study, from 2005 to 2015 the global incidence rate of HIV was about 2.6 million per year. In 2016 approximately 1.8 million of people were newly infected.
In 2016 1.0 million people died due to AIDS, 120.000 were children.
See also: Signs and symptoms of HIV
Transmission of HIV
As at 2012, in the USA and 6 dependent areas (according to CDC) diagnoses of HIV by transmission were:
- 64% – due to male-to-male sexual contact;
- 17% – heterosexual contact (females);
- 9% – heterosexual contact (males);
- 4% – injection drug use (males);
- 3% – injection drug use (females);
- 3% – male-to-male sexual contact + injection drug use;
- 1% – other (including hemophilia, blood transfusions, perinatal exposure etc.)
AIDS and opportunistic infections
AIDS (acquired immunodeficiency syndrome) is an advanced stage of HIV infection. A person experiences chronic diarrhea, night sweats, fever, persistent cough, and loses weight without any obvious reason. When the exhaustion is severe cachexia develops. This condition is know as HIV wasting syndrome.
The characteristic feature of AIDS is the development of opportunistic infections. Such infections include the following:
- Kaposi’s sarcoma
- Cytomegalovirus infection
- Herpes zoster
- Atypical pneumonia etc.
Antiretroviral therapy slows down the virus replication and postpones the development of AIDS. The treatment should be initiated as soon as possible and is required during the whole individual’s life. Once the viral load decreases the risk of transmission is reduced.
The most effective treatment is the one which includes the combination of anti-HIV drugs with which the patient hasn’t been treated in the past and that are not cross-resistant to other drugs that the patient has already received. Monotherapy is not recommended as drug resistance develops.
ART side effects
Reverse transcriptase inhibitors alter DNA polymerization reactions causing various side effects such as anemia, granulocytopenia, myopathy, lactic acidosis, hepatomegaly with steatosis, pancreatitis, peripheral neuropathy, headache, nausea, malaise etc.
HAART therapy with reverse transcriptase inhibitors is known to cause a syndrome of hyperlipidemia, glucose intolerance/insulin resistance, and fat redistribution (lipodystrophy syndrome).
The side effects of the entry inhibitors are: local injection reactions, hypersensitivity reactions, increased rate of bacterial pneumonia, hepatotoxicity, nasopharyngitis, fever, cough, rash, abdominal pain, dizziness, fever, musculoskeletal symptoms.