### Theory:

Disease: Acquired Immunodeficiency Syndrome (AIDS)
Acquired Immunodeficiency Syndrome is a disease (AIDS) caused by the pathogen HIV (Human Immunodeficiency Virus). It is a retrovirus and was first recognised in Haiti (USA) in $$1981$$. In India, the first confirmed evidence of AIDS infection was reported in April $$1986$$ from Tamil Nadu.
There are many vaccination trials conducted across the world to prevent the AIDS. The most prominent one is the RV $$144$$ vaccine trial which shows $$30%$$ reduced HIV risk. This trial was conducted in Thailand in $$2003$$, and reports were presented in $$2011$$.

HIV Virus

Causative organism:$$AIDS$$ is caused by a retrovirus (RNA virus) known as Human Immunodeficiency Virus (HIV).

Structure of HIV

Mode of transmission: It is transmitted through,
• A sexual contact (from an infected person to a healthy person)
• Blood contact (transfusion of unscreened blood)
• By surgical equipment (infected needles and syringes)
• Maternal – foetal transmission (from infected mother to the foetus via).
Mode of transmission and non transmission of HIV

Tissues/Organs affected: The immune system plays a vital role in fighting against infections in human body. Human Immunodeficiency Virus mainly attacks the white blood cells or lymphocytes (T-lymphocytes), acting as the body's immune system or self-defence mechanism. Over time, HIV weakens the body's immune system, so it has a tough time-fighting disease.

Symptoms:
Some of the important symptoms are,
• Weight loss
• Prolonged fever
• Sweating at night
• Chronic diarrhoea
Symptoms of HIV infection

Prevention and Control:

• Disposable syringes and needles should be used.
• Protected and safe sexual contact.
• Screening of blood before blood transfusion.
• People should be educated about $$AIDS$$ transmission.