Human Health And Disease

Human Papillomavirus (HPV), particularly high-risk types like HPV-16 and HPV-18, is the primary cause of cervical cancer. It can also lead to other cancers such as anal, oropharyngeal, penile, vaginal, and vulvar cancers, but cervical cancer is the most commonly associated.

Cretinism, caused by congenital hypothyroidism (often due to iodine deficiency), results in low basal metabolic rate (BMR), delayed puberty, and mental retardation. It leads to stunted growth and developmental delays if untreated.

Acquired (or adaptive) immunity is a specific type of defense that the body develops after exposure to an antigen (a foreign substance, typically from a pathogen). Its four unique features are:

Specificity: Acquired immunity is highly specific. The immune response generated against a particular pathogen (like the measles virus) is effective only against that pathogen. Antibodies or T-cells produced in response to one antigen will not recognize or react to a different antigen.
Diversity: The immune system is capable of recognizing and responding to an almost infinite variety of different antigens. This is due to the vast repertoire of B-lymphocytes and T-lymphocytes, each with unique receptors for a specific antigen.
Memory: A hallmark of acquired immunity is its ability to "remember" past infections. After an initial encounter with an antigen, the immune system produces memory B-cells and T-cells. If the same antigen is encountered again, these memory cells mount a secondary (anamnestic) response that is much faster, stronger, and more effective than the primary response, often preventing the disease from developing. This is the principle behind vaccination.
Discrimination between Self and Non-self: The immune system has the remarkable ability to distinguish between the body's own cells and molecules ("self") and foreign substances ("non-self"). This prevents the immune system from attacking and destroying the body's own tissues, a condition known as autoimmunity.

AIDS (Acquired Immunodeficiency Syndrome) is caused by the Human Immunodeficiency Virus (HIV). HIV is a blood-borne pathogen. One of the primary modes of transmission is through the sharing of contaminated needles and syringes, which can transfer infected blood from one person to another. Elephantiasis, Malaria, and Dengue are all vector-borne diseases, transmitted by insects (mosquitoes).