What are the various routes by which transmission of human immunodeficiency virus takes place?
AIDS (Acquired Immuno Deficiency Syndrome) is caused by the Human immunodeficiency virus (HIV). It has the following modes of transmission
(a) Unprotected sexual contact with an infected person.
(b) Transfusion of blood from a healthy to an infected person.
(c) Sharing infected needles and syringes.
(d) From an infected mother to a child through the placenta

Rishika and Shivika were partners in a firm sharing profits and losses in the ratio of 3 : 2. Their Balance Sheet as at 31st March, 2024 stood as follows:
Balance Sheet of Rishika and Shivika as at 31st March, 2024
| Liabilities | Amount (₹) | Assets | Amount (₹) |
|---|---|---|---|
| Capitals: | Equipment | 45,00,000 | |
| Rishika – ₹30,00,000 Shivika – ₹20,00,000 | 50,00,000 | Investments | 5,00,000 |
| Shivika’s Husband’s Loan | 5,00,000 | Debtors | 35,00,000 |
| Creditors | 40,00,000 | Stock | 8,00,000 |
| Cash at Bank | 2,00,000 | ||
| Total | 95,00,000 | Total | 95,00,000 |
The firm was dissolved on the above date and the following transactions took place:
(i) Equipements were given to creditors in full settlement of their account.
(ii) Investments were sold at a profit of 20% on its book value.
(iii) Full amount was collected from debtors.
(iv) Stock was taken over by Rishika at 50% discount.
(v) Actual expenses of realisation amounted to ₹ 2,00,000 which were paid by the firm. Prepare Realisation Account.
Immunity can be defined as the body's ability to guard itself against disease-causing organisms. In other words, it is the ability to resist infection by the action of particular antibodies. Our body has the ability to produce antibodies against pathogens and defend itself from diseases; therefore, we may come in contact with several viruses every day, but not get ill. This defense mechanism is therefore known as immunity.
The immunity, which is present in an organism by birth is called innate Immunity. Innate immunity refers to the body’s defence system. For example, the skin, the barrier of the human body functions by protecting the entry of germs and other disease-causing pathogens.
An individual acquires immunity after birth, hence is called adaptive or acquired immunity. Adaptive immunity develops throughout our lives. We acquire adaptive immunity when we are exposed to infectious diseases and allergies or when we are immunized against them with vaccines.
Passive immunity is developed by antibodies that are produced outside the body. This immunity lasts for a short time. For example, antibodies present in a mother’s breast milk provide a baby with temporary immunity against the diseases.
Active immunity is a type of adaptive immunity, which is developed due to the production of antibodies in one’s own body. This type of immunity occurs when we are in contact with the pathogen or its antigen.