Health And Its Failure

The term 'health' is commonly used, often implying a state of 'being well' or functioning effectively. However, the scientific definition of health goes beyond merely the absence of disease.

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The Significance Of ‘health’

In a broad sense, health means a state of being well enough to function effectively in various aspects of life.

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A widely accepted definition by the World Health Organisation (WHO) describes health as: a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity.

• Physical well-being: The body functions optimally without physical ailments.
• Mental well-being: The person is free from mental illness and can handle emotions, stress, and relationships effectively.
• Social well-being: The person can interact effectively with others and society, contributing positively and having a supportive social environment.

Being 'healthy' means being able to perform one's required functions effectively, whether it's physical tasks for an elderly person, mental concentration for a student, or specific abilities for a dancer or musician.

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Personal And Community Issues Both Matter For Health

Health is not solely an individual matter; it is significantly influenced by our surroundings and social environment.

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Our health depends on both the physical environment (e.g., air quality, availability of clean water, living conditions) and the social environment in which we live. Human beings live in communities (villages, towns, cities), and the collective actions and conditions within these communities directly impact individual health.

How Community Issues Affect Individual Health:

• Public Cleanliness and Sanitation: Lack of proper garbage collection and disposal, blocked drains, and stagnant water create breeding grounds for disease-carrying organisms (like mosquitoes) and can contaminate water sources. Poor public hygiene increases the risk of exposure to infectious agents, affecting individual health.
• Availability of Clean Drinking Water: Access to safe and clean drinking water is crucial for preventing water-borne diseases. This requires community-level infrastructure and management.
• Social Environment: Factors like social equality, harmony, security, and opportunities for earning a livelihood contribute to individual happiness and well-being, which are integral parts of health. Mistreatment, fear, and lack of opportunities in the community can negatively impact mental and social health.

Therefore, maintaining public health and hygiene requires collective responsibility and community action. Individual health is inextricably linked to community health.

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Distinctions Between ‘healthy’ And ‘disease-free’

While 'disease' literally means 'disturbed ease' or being uncomfortable, in a more specific sense, we refer to disease when there is an identifiable cause for discomfort or abnormal functioning.

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It is important to distinguish between being merely disease-free and being truly healthy.

• Disease-free: Simply means not suffering from a particular, identifiable disease.
• Healthy: A state of complete physical, mental, and social well-being, which allows one to function effectively and realise their potential.

It is possible to be disease-free but still be in poor health. For example, a person might not have any diagnosed illness but feels constantly tired, lacks energy, or experiences social anxiety due to poor nutrition, lack of exercise, or stressful living conditions. Such a person is disease-free but not healthy.

Conversely, someone might have a chronic condition that is managed, but they maintain a high level of physical, mental, and social well-being within the constraints of their condition – they might be considered healthy despite having a disease.

Thinking about health requires considering broader societal and community factors, while thinking about disease often focuses on the individual and the specific cause of their ailment.

Disease And Its Causes

Understanding disease involves recognising its manifestations (what it looks like), classifying different types of diseases, and identifying their underlying causes.

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What Does Disease Look Like?

We know there is a disease when the normal functioning of the body's systems (made up of organs and tissues) changes for the worse.

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These changes manifest as symptoms and signs of disease.

• Symptoms: These are the subjective feelings of being 'wrong' that a person experiences (e.g., headache, cough, fever, pain, nausea, fatigue, loose motions). Symptoms indicate that something is wrong, but they do not specifically identify the disease. A single symptom, like a headache, can be caused by many different conditions.
• Signs: These are objective observations that a physician looks for (e.g., elevated body temperature, swelling, changes in blood pressure, visible rash, results of laboratory tests). Signs provide more specific evidence of the presence of a particular disease and help the physician diagnose the condition.

Physicians use symptoms, signs, and laboratory tests to pinpoint the specific disease affecting an individual.

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Acute And Chronic Diseases

Diseases can be classified based on how long they last.

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• Acute Diseases: Diseases that last for a short period of time. Examples: Common cold, cough, influenza, typhoid fever. People usually recover fully from acute diseases.
• Chronic Diseases: Diseases that last for a long time, sometimes even a lifetime. Examples: Tuberculosis, elephantiasis, diabetes, high blood pressure, arthritis. Chronic diseases often have prolonged and significant effects on a person's health and daily life.

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Chronic Diseases And Poor Health

Both acute and chronic diseases affect health by interfering with the body's functions. However, their impact on overall, long-term health differs significantly.

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An acute disease, being short-lived, generally does not cause major, lasting damage to general health. A common cold, for instance, may cause discomfort for a few days, but there are usually no long-term health consequences.

A chronic disease, lasting for months or years, has drastic and prolonged effects on a person's general health. It can lead to weakness, weight loss, fatigue, reduced ability to perform daily activities (including learning in school), and significant long-term impairment of body functions. Therefore, chronic diseases have a much more severe impact on the health of the population compared to acute diseases.

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Causes Of Diseases

Identifying the cause of a disease can be complex, as diseases often have multiple contributing factors operating at different levels.

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Consider a baby with loose motions caused by an infection from unclean water. The immediate cause is the infectious agent. But why did this baby get sick while others exposed to the same water did not? Perhaps the baby's overall health was poor due to malnutrition. So, poor nourishment is a contributory cause. Further, why was the baby malnourished? Perhaps due to poverty, where access to sufficient food is limited. So, poverty is another underlying or contributory cause.

Thus, diseases typically have:

• Immediate Causes: The direct factors that trigger the disease (e.g., a specific microbe).
• Contributory Causes: Underlying factors that increase susceptibility or contribute to the severity of the disease (e.g., poor health, malnutrition, lack of access to clean water, poverty, genetic predisposition).

Most diseases are the result of the interaction of multiple causes rather than a single isolated factor.

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Infectious And Non-infectious Causes

Immediate causes of diseases can be broadly categorised into two types:

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1. Infectious Causes: Diseases caused by external agents, mostly microbes or micro-organisms. These are called infectious diseases because the causative agents can spread from one person to another or through the environment. Examples: Common cold, influenza, tuberculosis, malaria, cholera.
2. Non-infectious Causes: Diseases that are not caused by infectious agents spreading from external sources. Their causes are typically internal factors. These are called non-infectious diseases. Examples: Cancers (often linked to genetic factors or lifestyle), high blood pressure (linked to weight, diet, exercise), diabetes, heart disease. These diseases generally do not spread from person to person through external contact.

Understanding whether a disease is infectious or non-infectious is crucial for determining how it spreads, how it should be treated, and how it can be prevented at both individual and community levels.

Infectious Diseases

Infectious diseases are caused by various types of disease-causing organisms, known as pathogens or infectious agents.

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Infectious Agents

Infectious agents are found across various categories of living organisms, primarily microbes:

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• Viruses: Cause diseases like common cold, influenza, dengue fever, measles, AIDS, SARS, COVID-19. Viruses are very small and replicate inside host cells.
• Bacteria: Cause diseases like typhoid fever, cholera, tuberculosis, anthrax, acne, peptic ulcers. Bacteria are single-celled microorganisms.
• Fungi: Cause many common skin infections (e.g., ringworm).
• Protozoans: Single-celled animals that cause diseases like malaria (Plasmodium), kala-azar (Leishmania), sleeping sickness (Trypanosoma).
• Worms: Multicellular organisms that cause infections like intestinal worm infections (e.g., Ascaris - roundworm), and elephantiasis.

Identifying the category of the infectious agent is crucial for determining the appropriate treatment because different groups of microbes have distinct biological characteristics and biochemical pathways that can be targeted by specific drugs. For example, antibiotics effectively target bacterial processes (like cell wall synthesis) but are ineffective against viruses, which lack these pathways and use the host cell's machinery.

Peptic Ulcer Discovery: The discovery that peptic ulcers were caused by the bacterium Helicobacter pylori (by Marshall and Warren, Nobel Prize 2005) revolutionised treatment, changing it from managing symptoms to curing the infection with antibiotics.

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Means Of Spread

Infectious diseases are 'communicable' because the disease-causing microbes can spread from an infected person or source to others. They spread through various means:

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• Through Air (Airborne diseases): Spread through tiny droplets containing microbes expelled when an infected person coughs, sneezes, or talks. These droplets can be inhaled by people nearby. Risk increases in crowded and poorly ventilated areas. Examples: Common cold, COVID-19, pneumonia, tuberculosis.
• Through Water (Water-borne diseases): Occur when the excreta (feces) of a person with an infectious gut disease (like cholera or typhoid) contaminates drinking water sources. Microbes enter healthy individuals when they drink the contaminated water. More likely in areas with unsafe drinking water supply.
• Through Sexual Contact: Diseases transmitted during sexual activity. Examples: Syphilis, AIDS (caused by HIV). These are spread by close physical contact specific to sexual acts and not casual contact like handshakes or hugs. HIV can also spread through blood (transfusions, shared needles) or from mother to child during pregnancy, birth, or breastfeeding.
• Through Vectors: Animals that carry infectious agents from a sick person (or other source) to a healthy person. These animals act as intermediaries. Common vectors are mosquitoes, which feed on blood and can transmit pathogens (e.g., mosquitoes transmit malaria parasite).

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Organ-specific And Tissue-specific Manifestations

Disease-causing microbes enter the body through different entry points (e.g., nose, mouth, sexual organs, skin break). Once inside, they often target specific organs or tissues where they cause infection.

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Different species of microbes have evolved to infect particular parts of the body. The target organ/tissue is often related to the entry point (e.g., airborne microbes entering via the nose are likely to target the lungs, causing tuberculosis or pneumonia; microbes entering via the mouth may target the gut or liver, causing typhoid or jaundice).

However, some microbes can spread widely regardless of the entry point (e.g., HIV, entering via sexual organs, targets the immune system and lymph nodes; malaria parasites, entering via mosquito bite, go to the liver and then red blood cells; Japanese encephalitis virus, via mosquito bite, targets the brain).

The signs and symptoms of a disease are determined by the function of the targeted organ or tissue. If the lungs are infected, symptoms relate to breathing (cough, breathlessness). If the liver is infected, symptoms relate to liver function (jaundice). If the brain is infected, symptoms relate to brain function (headache, vomiting, fits).

Besides these specific effects, infectious diseases often cause common symptoms related to the body's response to infection, mainly the activation of the immune system. The immune response often involves inflammation (recruiting immune cells to the site of infection), causing local effects like swelling and pain, and general effects like fever.

In some diseases (like HIV-AIDS), the target is the immune system itself. Damage to the immune system leaves the body vulnerable to many other infections that it would normally fight off easily. These secondary infections (e.g., pneumonia, severe diarrhoea) are often the direct cause of severe illness or death in immunocompromised individuals.

The severity of a disease also depends on the number of microbes in the body. A small number might cause mild or unnoticed symptoms, while a large number can lead to severe, life-threatening disease. The immune system plays a critical role in controlling the number of microbes.

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Principles Of Treatment

When someone falls ill with an infectious disease, treatment aims to achieve two main goals:

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1. Reduce the effects of the disease (symptom relief): Provide treatments that lessen the symptoms, such as medicines for fever, pain, or loose motions. Resting in bed also helps conserve energy for healing. This type of treatment makes the patient feel better but does not eliminate the microbes.
2. Kill the cause of the disease (eliminate the microbes): Use specific medicines designed to kill the disease-causing microbes.

Drugs that kill microbes (like antibiotics, antivirals, antifungals, antiprotozoals) work by targeting specific biochemical pathways or processes that are essential for the survival or reproduction of the particular type of microbe, but are not used by human cells. For example, antibiotics like penicillin target bacterial cell wall synthesis, a process unique to bacteria, thereby killing them without harming human cells.

Developing anti-viral drugs is challenging because viruses use the host cell's machinery for replication, limiting the number of virus-specific targets. Despite this, effective anti-viral drugs exist (e.g., for HIV infection).

Symptom relief alone is insufficient to cure an infectious disease; eliminating the infectious agent is necessary for full recovery.

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Principles Of Prevention

While treating diseases is essential, preventing them from occurring in the first place is always preferable due to several limitations of treatment: damage to body functions may be permanent, recovery takes time, and sick individuals can spread the infection to others. There are two main approaches to preventing infectious diseases: general prevention and disease-specific prevention.

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General Principles of Prevention: These aim to prevent exposure to infectious microbes.

1. Public Hygiene and Sanitation: Reducing exposure to microbes through community-level measures.
   • Preventing airborne infections: Avoiding overcrowded living conditions.
   • Preventing water-borne infections: Providing safe drinking water by treating it to kill microbes.
   • Preventing vector-borne infections: Providing clean environments to prevent vector breeding (e.g., controlling mosquito breeding sites).
2. Availability of Proper and Sufficient Food/Nourishment: A strong immune system is crucial for fighting off infections. Malnutrition weakens the immune system, making individuals more susceptible to diseases and less likely to recover effectively. Adequate food and nourishment for everyone is fundamental to building strong immunity and preventing severe illness.

Even when exposed to infectious microbes, a person with a healthy and active immune system can often fight off the infection or experience only mild symptoms, preventing the development of noticeable disease. Severe infectious disease often indicates a failure of the immune system, which can be compromised by factors like malnutrition.

Disease-Specific Principles of Prevention (Immunisation): This approach leverages the immune system's ability to develop memory for specific infections.

The principle of immunisation (or vaccination) involves exposing the immune system to something that mimics the infectious microbe without causing the actual disease. When the immune system encounters this mimic (e.g., weakened or killed microbes, or parts of microbes) for the first time, it mounts a response and develops a memory of that specific pathogen.

If the body is later exposed to the actual, live, virulent microbe, the immune system remembers it and reacts much more strongly and quickly, eliminating the infection before it can cause disease.

Historically, traditional methods (like variolation against smallpox) attempted to induce immunity. Edward Jenner's work with cowpox (a milder disease related to smallpox) led to the development of the first vaccine, paving the way for modern vaccination programmes. 'Vaccination' comes from the Latin word 'vacca' for cow, and 'vaccinia' for cowpox.

Many vaccines are available today for preventing a wide range of infectious diseases (e.g., tetanus, diphtheria, whooping cough, measles, polio, hepatitis B). These vaccines form the basis of childhood immunisation programmes, a vital public health strategy for preventing infectious diseases in the community. Effective prevention through immunisation requires ensuring that vaccines are accessible to all children.

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