Q.What does the abbreviation AIDS stand for?

AIDS (Acquired Immuno Deficiency Syndrome) is caused by the retrovirus HIV, which destroys T4 (helper T) lymphocytes, progressively crippling the immune system and exposing the patient to opportunistic infections and malignancies. First noticed in the USA (1981); India's first case was reported from Tamil Nadu (1986).

HIV structure: a spherical, 100-140 nm particle with a core of two ssRNA strands plus reverse transcriptase, enclosed by capsid protein (p24) and matrix protein (p17) layers, and an outer lipid envelope studded with glycoproteins Gp120 and Gp41.

Transmission: unsafe sexual contact, blood (transfusion/shared needles), and mother-to-child (placental or via breast milk) — not by casual contact like hugging, handshakes or insect bites.

Clinical course: initial infection/antibody formation (2-8 weeks) -> asymptomatic carrier state (6 months-10 years) -> AIDS-related complex (ARC) -> AIDS itself, marked by opportunistic infections (pneumonia, tuberculosis, Kaposi's sarcoma). …