2. ACQUIRED IMMUNO DEFICIENCY
SYNDROME(AIDS)
Acquired Immuno Deficiency Syndrome is an infections disease of the
immune system caused by the HIV virus and is characterized by the
decrease in the number of helper T cells which cause a severe
immunodeficient that leaves the body susceptible to a variety of
potentially fatal infections like pneumonia,TB,Candiasis etc
Causative Agent:Human Immunodeficiency Virus I(Most common)
and Huma Immunodeficiency Virus II
4. SIGNS AND SYMPTOMS
Swelling of lymph nodes
Dry cough
Pneumonia
Sire throat
Muscle and Joint pain
Headche and fever
Skin rashes
Night sweats
Nausea, Vomiting & Diarrhoea
Nail thickening and curving
Wasting Syndrome (Involuntary loss of weight)&fatigue
5. STAGES OF HIV
Acute HIV syndrome (3-12 weeks):This is the initial stage accompanied by flu like symptoms.It include:
(a) High levels of plasma viraemia due to replication of the virus.
(b) Virus specific immune response by formation of anti HIV antibodies after 3-6 weeks of initial exposure to HIV.
(c) Initially sudden marked reduction in CD4+ T cells followed by return to normal levels.
(d) Rise in CD8+ T cells.
(e) Flu like symptoms like sore throat, myalgia,skin rash etc.
Middle chronic phase(10-12 years):This phase involves competition between HIV and host immune response as under:
(a) Viraemia due to viral replication in the lymphoid tissue continues and viral load increases.
(b)Chronic stage depending upon host immune system may continue as long as 10 years.
(c) CD4+ T cells continue to proliferate but net result is moderate fall in CD4+ T cell counts.
(e) CD8+ T cell count remains high.
(f) Clinically it is the stage of latency and the patient remain asymptomatic.
6. Stages of HIV
Final crisis phase:This phase is characterized by profound immunosuppression and onset of full blown AIDS
and has the following features:
(a) Marked increase in Viraemia.
(b) The time period from HIV infection through chronic phase into full blown AIDS may last 7-10 years and
culminate in death.
(c) CD4+ T cells are markedly reduced(below 200 cubic millimeter)
The average survival after full blown AIDS is about 2 years.
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9. DIAGNOSTIC METHODS
(1) Tests for establishing HIV infection:
(a) Antibody tests
(i) ELISA(Enzyme Linked Immunosorbent Assay):It is a plate based assay technique designed for detecting and
quantifying peptides,proteases, antibodies and hormones.It is of three types:Direct,Indirect and Competitive ELISA.
(ii) Western blotting:It is an analytical technique used to identify and locate specific proteins in a sample of tissue
homogenate or extract based on their ability to bind to specific antibodies.
(b) Direct detection of HIV
(i) p24 antigen capture assay
(ii) HIV RNA assay methods by reverse transcriptase PCR,branched DNA,nucleic acid sequence based
amplification.
(iii) DNA-PCR by amplification of proviral DNA.
(iv) Culture of HIV from blood monocytes and CD4+ T cells.
10. DIAGNOSTIC METHODS
Tests for defects in immunity:These tests are used for diagnosis as well as monitoring treatment of cases.
(a) CD4+ T cell counts: Progressive fall in number of CD4+ T cells is of paramount importance in diagnosis and
staging.
(b) Rise in CD8+ T cells.
(c) Reversal of CD4+ to CD8+ T cell ratio.
(d) Lymphopenia
(e) Polyclonal hupergammaglobulinaemia
(f) Increased beta-2- microglobulin levels
(g) Platelet count revealing thrombocytopenia
Tests for detection of oppurtunistic infections and secondary tumours: Diagnosis of organs involved in
oppurtunistic infection and specific tumours secondary to HIV/AIDS is made by aspiration or biopsy methods.
