ACQUIRED IMMUNODEFICIENCY SYNDROME (AIDS) :-
- AIDS was first reported in 1981 in USA. Here syndrome means group of symptoms.
AIDS Disease
(1) the causative agent is HUMAN IMMUNODEFICIENCY VIRUS (HIV).
(2) HIV belongs to a group of viruses called retrovirus. It has RNA is ssRNA which forms DNA via reverse transcription process using enzyme reverse transcriptase.
(3) HIV is transmitted by
(a) sexual contact with infected person.
(b) Transfusion of contaminated blood and blood products.
(c) sharing infected needles.
(d) infected mother to unborn child through placenta.
(4) people who are susceptible to infection are:
(a) Drug addicts, who take intravenous drug injections.
(b) individuals who are involved with multiple sexual partners.
(c) individuals who require repeated blood Transfusion.
(d) children born to HIV positive mother.
(5) MODES OF HIV INFECTION :-
(a) virus enters the macrophages, after entering into the body of a person.
(b) RNA gets replicated to form viral DNA by enzyme reverse transcriptase. This process is known as REVERSE TRANSCRIPTION.
(c) viral DNA gets incorporated into the host cell DNA and directs the infected cells to produce virus particles.
(d) these virus particles enter into helper T-lymphocytes (TH cells) in the blood, where they continue to replicate and produce viral progenies. Due to this, Th cells are destroyed.
(e) The number of helper T-lymphocytes progressively decreases in the body of the infected person.
(f) As the number of helper T-lymphocytes decreases, the immunity also decreases,. As a result, person cannot produce any immune response even against common bacteria like mycobacterium, parasite like Toxoplasma, viruses and fungi.
(g) MACROPHAGES continue to produce virus particles throughout the process and thus, act as HIV factory.
(h) ELISA (Enzyme Linked Immuno sorbent Assay)
(i) Treatment with anti-retoviral drugs is only partially effective. They can only prolong the life of patient but cannot prevent death.
PREVENTION OF AIDS:
- certain preventive measures that can prevent HIV infections are
(1) National AIDS Control Organisation (NACO) setup in 1991 and other NGOs educate people about AIDS.
(2) Role of WHO in preventing HIV infection
* Ensure use of disposable syringes and needles.
* Ensures that blood banks are safe from HIV.
* Free distribution of condoms.
* prevention of drug abuse.
* Discouraging unsafe sex and encouraging regular check up for HIV in susceptible populations.
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