Common Diseases
* Health is regarded as a state of complete physical, mental and social well-being.
* Infectious diseases are those that can e transmitted from one person to another.
* Diseases can be caused y a variety of organisms such as bacteria or fungi. All diseasecausing organisms are called pathogens.
* Some common pathogens are bacteria, viruses, helminths and fungi.
* Bacteria cause diseases such as thyroid, pneumonia, dysentery, plague and diphtheria.
* Helminths, Ascaris and Wuchereria are responsible for causing pathogenic diseases such as ascariasis and filariasis in human beings whereas fungi cause ringworm in human beings.
Infectious Disease and Their Prevention
* Malaria is caused by a tiny parasitic protozoan called Plasmodium.
* Amoebiasis or amoebic dysentery is another disease caused by a protozoan called
* Entamoeba histolytica that lives in the large intestine of human beings.
* Maintaining both personal and public hygiene is crucial for the prevention and control of several infectious diseases.
* Most infectious diseases like typhoid, amoebiasis and ascariasis are spread by vectors that are transmitted via contaminated food and water.
* To prevent air-borne diseases like pneumonia and the common cold from spreading, care must be taken to avoid contact with infected persons and their belongings.
Types of Immunity
* Immunity is the overall ability of a host to fight disease-causing organisms.
* Immunity is of two types: innate and acquired.
* Innate immunity is a non-specific type of defence whereas acquired immunity is
* pathogen-specific.
* Acquired immunity or the acquired immune response is primarily of two types: the humoral immune response and cell-mediated immunity (CMI).
* Based on whether antibodies are produced inside or outside the body, immunity can be distinguished as active immunity or passive immunity.
Principles of Immunity
* The memory of the immune system is used as a principle in an immunisation programme.
* Sometimes, when a quick immune response is required, for instance when the body is infected by deadly microbes, pre-formed antibodies are injected into the body. This type of immunisation, involving pre-formed antibodies, is called passive immunisation.
* Sometimes, due to genetic reasons, the body attacks itself or self-cells. The attack damages the body and is called an auto-immune response.
* The exaggerated immune response to certain antigens in the environment is called an allergy.
Immune System In The Body
* The human immune system consists of lymphoid organs, tissues, cells and antibodies.
* Bone marrow and the thymus are two primary lymphoid organs.
* The secondary lymphoid organs are the spleen, lymph nodes, tonsils Peyer’s patches of the small intestine and appendix.
* Mucosal-associated Lymphoid Tissue or MaLT constitutes about 50% of lymphoid tissue inside the body.
AIDS
* AIDS stands for Acquired Immuno Deficiency Syndrome.
* AIDS is caused by the Human Immuno Deficiency Virus (HIV) that belongs to a group of viruses known as retroviruses.
* The HIV infection is usually transmitted through any one of the following four ways.
• Sexual contact with an HIV infected person
• Transfusion of infected blood
• Sharing of infected needles.
• From infected mother to child
* AIDS spreads only through body fluids; it is not transmitted by mere touch or physical contact.
* The ELISA or Enzyme Linked Immuno- Sorbent Assay test is commonly used to diagnose AIDS whereas anti-retroviral drugs are used to treat AIDS.
Cancer
* Cancer is characterised by the uncontrollable growth of the body’s cells where the cell property of contact inhibition is completely lost.
* Tumours are either benign or malignant.
* Benign tumors cause little damage as they do not spread to other parts of the body whereas malignant tumors grow very rapidly and damage surrounding tissues.
* The physical, chemical and biological agents responsible transforming normal cells into cancerous neoplastic cells are known as carcinogens.
* Cancer is detected by using a variety of methods such as a biopsy, histopathology of blood as well as tissue and bone marrow tests.
* Cancer is usually treated by a combination of surgery, radiation therapy and immunotherapy.
* Substances that activate the immune system are called biological response modifiers.
Drug Abuse and Smoke Addiction
* Certain drugs when consumed in inordinate amounts cause physical, physiological and psychological damage. This phenomenon of overuse of drugs is often referred to as drug abuse.
* Some overused drugs are opioids, cannabinoids and coca alkaloids.
* Opioids are drugs that bind to specific receptors in our central nervous system and gastrointestinal tract.
* Cannabinoids are a group of chemicals that bind to cannabinoid receptors, which are found chiefly in the brain.
* Excessive dosage of coca alkaloids such as cocaine causes hallucinations.
* Like drugs, tobacco too has a chemical substance called nicotine that causes addiction.
* Drug and smoke addicts should be helped with professional counselling and medical assistance.
Adolescence, Addiction and Dependence
* The period between 12 and 18 years, when every child undergoes both physical and behavioural changes, is known as ‘adolescence’.
* Adolescence is a bridge between childhood and adulthood.
* The inherent addictive nature of both alcohol and drugs ensures that with repeated use of drugs and alcohol, the tolerance level of receptors present in the body increase.
* Dependence is defined as the tendency of the body to display unpleasant withdrawal symptoms if the regular dose of drugs or alcohol is discontinued.
* Adequate moral support and counselling is required during adolescence to avoid substance abuse among youngsters.
* Also, medical care along with counselling is a must for addicted individuals.
Drug and Alcohol Abuse-Effects and Prevention
* Excessive use of drugs can cause coma or death due to respiratory, heart or cerebral damage.
* The immediate effects of drug abuse can result in reckless behaviour vandalism and sometimes violence.
* The identifying signals of drug and alcohol abuse are withdrawal, unnaturally glazed, disregard for personal hygiene, depression, fatigue, isolation and rebellious behaviour.
* Drug abusers who take drugs intravenously are also susceptible to fatal diseases such as AIDS and Hepatitis B.
* Keeping in mid the severity of the damaging effects of drug abuse, it is better to focus on prevention of drug abuse, especially among adolescents since they are most vulnerable during this period.
* Professional psychologists, psychiatrists and deaddiction and rehabilitation programmes can also be sought to help drug abusers.