HIV & AIDS in Children
HIV (Human Immunodeficiency Virus) is a unique type of virus (i.e. a retrovirus) that invades the T- helper cells (CD4 cells) in the body of the host (defense mechanism of a person).
AIDS (Acquired Immunodeficiency Syndrome) is a disease of the human immune system caused by infection with human immunodeficiency virus. In children it is acquired perinatally or by vertical -maternal-infant transmission.
HIV is the virus that causes AIDS
Introduction to HIV & AIDS in Children.
Considerable progress has been made towards eliminating human immunodeficiency virus (HIV) among children; however, the global burden of pediatric HIV and acquired immune deficiency syndrome (AIDS) remains a challenge for health care workers around the world, particularly in developing countries.
Epidemiology
Each day, some 1500 children under 15 years of age become infected with HIV, an estimated 90% of whom live in sub-Sahara-Africa. In 2005, there were 2.3 million (1.7–3.5 million) children living with HIV worldwide, most of whom acquired the virus in utero, during birth or while being breastfed, ways of contracting HIV that can be prevented.
For many children infected with HIV, the chances of survival are slim. Worldwide, AIDS now accounts for 3% of deaths in children under five years of age—and 6% of those in sub-Saharan Africa, where AIDS has become one of the major killers of young children.
One in seven people dying of HIV-related illness worldwide is a child under 15 years old. This is due largely to the failure to introduce programs for preventing mother-to-child transmission of HIV on the scale needed. Without HIV care, including antiretroviral therapy, the progression of HIV infection in children is particularly aggressive. In 2005, an estimated 380 000 (290 000–500 000) children died of HIV-related causes. It is likely that one half of them did not live past their second birthday.
Mode of Transmission
There are several potential modes of transmission of HIV to children:
- Mother to child transmission: more than 95% of HIV-infected infants in Africa acquire HIV from their mothers during pregnancy, at the time of delivery, or potentially through breast feeding. Without any intervention, between 30 to 40% of breast-feeding HIV positive women transmit HIV to their newborns.
- Sexual transmission among adolescents
- Sexual abuse of children
- Transfusion of infected blood or blood products
- Unsterile injection procedures, and scarification
Risk factors for mother to child HIV-transmission
The risk factors associated with maternal to child transmission include the following:
- Women with high viral load are more likely to transmit HIV to their newborns
- Women with severe immunosuppression (CD4 count below 200) and those with advanced disease.
- Maternal micronutrient deficiencies increase the risk of MTCT of HIV significantly
- Prolonged rupture of membranes, chorioamnionitis, and STIs
- During breastfeeding, cracked nipples and breast abscesses
- HIV-1 is more readily transmitted from an HIV-infected woman to her infant than is HIV-2.
Pathogenesis
- The human body is made out of millions of different cells. Each body cell often makes new cell parts in order to stay alive and to reproduce.
- Viruses hide their own material inside the cells of the body, and then, when the body cells try to make new parts, they accidentally make new viruses as well.
- HIV mostly enters cells of the immune system.
- Although HIV infects a variety of cells, its main target is the T4-lymphocyte (CD4): a kind of white blood cell that is responsible for warning the immune system that there are invaders (diseases) in the body.
- Once HIV binds to a cell structure, it hides its material inside the cell. This turns the cell into a sort of HIV factory.
- HIV enters the CD4 cell VIRAL GP120- (fusion and entry)
- Now, HIV enters the centre of the cell. To do this, it needs to make some important changes in the way it looks so that it will not be ‘recognized’ by the cell. HIV has a special substance to make these changes in its structure.- (reverse transcription)
- HIV is present in the centre of the cell, but in a different shape- (integration to genome).
- The centre of the cell starts to make new parts of HIV instead of making new parts for the body’s defence. (transcription and translation).
- Before leaving the cell, the new parts of HIV need to be put together, just like parts of a car need to be put together in the factory before they can leave the factory to be sold. HIV has a special substance that helps to put the different parts together to form a new HIV before it leaves the cell- budding
- HIV attacks many CD4 cells. The infected CD4 cells will first produce many new copies of the virus, and then die. The new copies of HIV will then attack other CD4 cells, which will also produce new copies of HIV and then die. This goes on and on: more and more CD4 cells are destroyed, more and more new copies of HIV are made, and new CD4 cells get infected.
Steps / Phases in HIV entry
CD4 & chemokine receptors are needed for HIV entry therefore the following are the phases
- Viral Entry: Binding of gp 120, CD4 and chemokine receptors results in changes in gp41 and fusion of the virion and cell surface membrane. Strands of viral RNA are released into the cell cytoplasm
- Reverse Transcription: In nature DNA produces RNA, but retroviruses can convert single stranded RNA into double stranded DNA using an enzyme called reverse transcriptase
- Integration: Viral DNA integrates into the host chromosome DNA to form a provirus
- Transcription: back to RNA. In activated lymphocytes, transcription of viral DNA results in production of multiple copies of viral RNA. HIV RNA has 9 genes which code for the production of structural proteins like the viral envelope and core, in addition to reverse transcriptase, integrase,
and protease - Translation: RNA to protein
- Viral protease; Viral protease cleaves [cuts] the polypeptide chain into enzyme components like integrase and reverse transcriptase which help produce new virions
- Assembly and budding: Viral RNA and proteins are packaged and released from lymphocyte surface
How HIV attacks the body.
- The CD4 (white blood cell), is a friend of the body. Problems like cough, diarrhoea try to attack the body, but the CD4 fights them to defend the body, its friend.
- Now, HIV enters and starts to attack the CD4. The CD4 notices it cannot defend itself against HIV. Soon, CD4 loses its fight against HIV. The body remains without defence.
The body is all alone, without defence, so all kinds of problems, like cough and diarrhoea take advantage and start to attack the body. In the end, the body is so weak that all diseases can attack without difficulty.
Good but description of HIV treatment regimen