Comprehensive theory, key formulas, diagrams, and memory aids for Why Do We Fall Ill.
Health and disease are complex issues in our communities. We often hear the word 'health' used in everyday conversation. "My grandmother's health is not good." Our teachers use it when they scold us saying, "this is not a healthy attitude." What does this word actually mean?
If we realize that cells are the fundamental units of living beings and are constantly engaged in a variety of dynamic activities, we understand that anything that prevents proper functioning of cells and tissues will lead to a lack of proper activity of the body. In this chapter, we will look at health, diseases, how we get sick, and how to prevent it.
The World Health Organisation (WHO) defines health as a state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity. * Physical well-being: Normal functioning of the body and its organs. * Mental well-being: A state of emotional and psychological balance. * Social well-being: Living in harmony with society and having basic necessities (food, shelter, clean environment).
Because health depends on physical, mental, and social factors, personal health is deeply connected to community health. Public cleanliness, good economic conditions, and social equality are necessary for individual health.
Being "disease-free" is not the same as being "healthy." A person can be free of a specific identifiable disease but still suffer from poor mental health or be socially isolated. Disease-free relates only to the individual, while health relates to the individual's physical, social, and mental environment.
When a person has a disease, either the functioning or the appearance of one or more systems of the body will change for the worse. These changes give rise to symptoms (things we feel as being 'wrong', like a headache, cough, or loose motions) and signs (what physicians look for based on symptoms to find the specific disease).
Most diseases have multiple causes. * Immediate Causes (Infectious agents): Microbes like viruses, bacteria, fungi, and protozoans. Diseases caused by them are called infectious diseases because the microbes can spread in the community. * Contributory Causes (Non-infectious): Poor nourishment, genetic abnormalities, lack of public services (clean water), or lifestyle factors (lack of exercise, obesity). Diseases not caused by infectious agents (like high blood pressure or cancer) are called non-infectious diseases.
We can categorize infectious agents into a few broad groups: 1. Viruses: Cause common cold, influenza, dengue fever, and AIDS. 2. Bacteria: Cause typhoid fever, cholera, tuberculosis, and anthrax. 3. Fungi: Many common skin infections (like ringworm) are caused by different species of fungi. 4. Protozoans: Cause malaria (Plasmodium) and kala-azar (Leishmania). 5. Worms (Helminths): Intestinal worm infections and elephantiasis.
Note on Antibiotics: Antibiotics commonly block biochemical pathways important for bacteria. For example, penicillin blocks the bacterial processes that build the cell wall. Human cells don't make cell walls, so penicillin has no effect on us. Viruses do not use these pathways at all, which is why antibiotics do not work against viral infections.
Infectious diseases are also called communicable diseases because they can spread from an infected person to a healthy person. * Air-borne: Through the air (droplet infection from sneezing or coughing). e.g., Common cold, Tuberculosis, Pneumonia. * Water-borne: Spread when excreta from someone suffering from an infectious gut disease gets mixed with the drinking water used by people living nearby. e.g., Cholera. * Sexual Contact: Diseases transmitted by sexual contact. e.g., Syphilis, AIDS. (Note: AIDS can also spread through blood transfusions or from mother to baby). * Vectors: Animals or insects that carry the infecting agents from a sick person to a healthy person. e.g., Female Anopheles mosquito transmits Malaria.
The disease-causing microbes enter the body through different means and go to different organs. * Microbes entering through the nose usually go to the lungs (e.g., Tuberculosis). * Microbes entering through the mouth can stay in the gut lining (e.g., Typhoid) or go to the liver (e.g., Jaundice). * HIV enters via sexual organs or blood and spreads to lymph nodes all over the body, severely damaging the immune system.
The signs and symptoms of a disease depend on the tissue or organ the microbe targets. (e.g., if lungs are the target, symptoms are cough and breathlessness).
There are two ways to treat an infectious disease: 1. Reduce the effects of the disease: Provide symptomatic treatment to reduce pain, fever, or inflammation (using painkillers, taking bed rest to conserve energy). This does not kill the microbe. 2. Kill the cause of the disease: Use medicines that kill the specific infectious agents (e.g., using antibiotics for bacteria, antimalarial drugs for protozoa).
Prevention of diseases is always better than cure because curing takes time, the patient suffers, the disease may cause permanent damage, and the infected person serves as a source of spread.
There are two ways of prevention: 1. General Ways of Preventing Infection: * Air-borne: Avoid overcrowding and provide proper ventilation. * Water-borne: Provide safe drinking water (treating water to kill microbial contamination). * Vector-borne: Provide clean environments; do not allow water to stagnate to prevent mosquito breeding. * Proper Nutrition: A functioning immune system requires proper nourishment to fight off infections daily.
2. Specific Ways of Prevention (Immunization): Our immune system has a 'memory'. When a microbe attacks the body for the first time, the immune system responds and remembers it specifically. The next time that particular microbe (or its close relatives) enters the body, the immune system attacks it with even greater vigor. This is the basis of Immunization (vaccination). * Vaccines "fool" the immune system into developing a memory for a particular infection by introducing something that mimics the microbe (often dead or weakened microbes) without causing the severe disease. * Examples of vaccines: Tetanus, Diphtheria, Whooping cough, Measles, Polio, and COVID-19.
Health is a multifaceted state of well-being requiring a balance of physical, mental, and social factors. Diseases can be acute or chronic, infectious (caused by microbes) or non-infectious. Infectious diseases spread through air, water, sexual contact, and vectors. While we can treat bacterial infections with antibiotics, viruses require different approaches, primarily immune response. Ultimately, prevention through public hygiene, proper nutrition, and specific immunization (vaccines) is the most effective way to deal with infectious diseases.