Human Health and Disease

Human Health and Disease 🌍🩺

Definition of Health and Disease 🏥

Health is defined as a state of physical and mental well-being 😊. A disease is any physical or mental disorder that interferes with the normal functioning of the body and has a characteristic set of signs and symptoms ⚠️.

Signs: Observable or measurable indications of a disease, such as a rash, high temperature, or weight loss 📉.

Symptoms: Indications of a disease that can only be felt and described by the patient, such as headaches, pain, nausea, and dizziness 🤕.

Categories of Diseases 🦠

Diseases can be categorized into two main types: infectious diseases (transmissible) and non-infectious diseases (non-transmissible) 🚫.

Infectious Diseases 🦠

Infectious diseases can be transmitted from person to person and are primarily caused by pathogens—disease-causing organisms, mainly microorganisms 🦠. Pathogens include viruses, bacteria, protozoa, fungi, and worms.

Methods of Transmission:

Through Vectors:
- Mechanical Vectors: Carry pathogens on their body surface (e.g., houseflies transmitting cholera 🪰).
- Biological Vectors: Carry pathogens inside their bodies, where the pathogen undergoes part of its life cycle (e.g., mosquitoes transmitting malaria 🦟).
Inhalation of Infected Droplets: Respiratory diseases spread when a healthy person inhales droplets released by an infected person through coughing or sneezing (e.g., tuberculosis, pneumonia, influenza 😷).
Contaminated Food and Water: Diseases like cholera and typhoid spread through ingestion of contaminated food and water 🍽️💧.
Contact with Infected Water: Diseases such as bilharzia and hookworm infections can occur from exposure to infected water 🌊.
Contact with Infected Organisms: Skin infections like ringworm, athlete’s foot, and thrush can spread through direct contact 🤲.
Sexual Intercourse: Diseases such as gonorrhea, syphilis, and AIDS are spread through sexual contact ❤️.

Summary of Selected Pathogenic Diseases:

Disease	Causative Agent	Signs and Symptoms	Methods of Transmission	Treatment and Control
Bilharzia	Schistosoma (S. mansoni, S. haematobium)	Anemia, tiredness, blood in urine and feces 🩸	Exposure to cercaria larvae in water 🌊	Sanitary disposal, boiling water, drug treatment 💊
AIDS	Human Immunodeficiency Virus (HIV)	Weight loss, skin cancer, opportunistic infections ⚠️	Sexual contact, infected blood, mother-to-child ❤️	Avoid unprotected sex, faithful partners, blood screening 🩸
Malaria	Plasmodium	Headache, fever, anemia, muscle pain 🤒	Bite from female Anopheles mosquito 🦟	Antimalarial drugs, mosquito control 💊
Cholera	Vibrio cholera	Vomiting, diarrhea, dehydration 🤮💧	Contaminated food and water, contact with infected person 🍽️	Sanitary disposal, boiling water, antibiotics, ORS treatment 💊

Non-Transmissible Diseases 🚫

These diseases cannot be passed from one person to another and are categorized as follows:

Nutritional Deficiency Diseases: Result from poor diets lacking essential nutrients (e.g., marasmus, kwashiorkor, rickets 🍏).
Genetic (Inherited) Diseases: Passed through genes from parents to offspring (e.g., sickle cell anemia, hemophilia, Down syndrome 🧬).
Degenerative Diseases: Characterized by gradual organ decline due to aging or stress (e.g., arthritis, coronary heart disease 🦴).
Environmental Diseases: Caused by pollutants in the environment (e.g., bronchitis, emphysema, lung cancer 🌫️).
Mental Disorders: Disorders of the mind due to chemical or physical factors (e.g., schizophrenia 🧠).
Self-Inflicted and Social Diseases: Conditions such as drug addiction 🚫.

Immunity 🛡️

Immunity refers to the body’s resistance to infection due to the presence of antibodies in the blood 🩸. Antibodies are proteins produced by lymphocytes that destroy antigens from infectious or foreign bodies. Each type of antibody is specific to one type of antigen, and the body can only produce antibodies against antigens it has encountered.

Types of Immunity 🛡️

Immunity can be classified into two main types: active and passive.

Active Immunity: The body actively produces antibodies 💪.
Passive Immunity: The body receives ready-made antibodies from an external source 🩸.

Both active and passive immunity can be natural (acquired through natural means like infections or breastfeeding) or artificial (acquired through man-made methods such as vaccination 💉).

Types of Immunity:

Type of Immunity	Definition or Description	Examples
Natural Active Immunity	Immunity developed through natural infection, stimulating antibody production.	Immunity to measles after infection 🤒.
Artificial Active Immunity	Introduction of dead or weakened germs into the bloodstream to stimulate antibody production.	BCG vaccination against tuberculosis, polio vaccine, cowpox vaccine 💉.
Natural Passive Immunity	Ready-made antibodies introduced through natural means (e.g., breastfeeding) 👶.	Antibodies passed from mother to baby.
Artificial Passive Immunity	Injection of immune serum containing ready-made antibodies for immediate protection.	Anti-venom injections, anti-tetanus serum 💉.

Importance of Immunity 🛡️

Immunity is crucial for disease prevention. Factors that can reduce immunity include:

Poor diet 🍔
Development of resistant strains of pathogens 🦠
Frequent pathogen invasions 🚪
Use of immunosuppressive drugs 💊
HIV infection, which destroys lymphocytes 🦠.

Immunity Response 🛡️

Primary Response: The immune response after the first exposure to an antigen, resulting in the production of memory cells 🧠.
Secondary Response: The immune response after subsequent exposures, which is more rapid and robust than the primary response ⚡.