CLASS 8 BIOLOGY : HEALTH AND HYGEINE

• Communicable diseases result from infectious agents transmitted from infected to healthy individuals directly or indirectly.
• These are also known as infectious diseases acquired through agents like air, water, physical or sexual contact, or insects.
• Pathogens, such as bacteria, viruses, and fungi, are disease-causing germs.

Key Concepts

• Health is a state of complete physical, mental, and social well-being, not just the absence of disease.
• Disease is an abnormal condition affecting the body's normal functioning.

Communicable Diseases

• An overview of some communicable diseases, including their causative agents, symptoms, transmission methods, and preventive measures.
• Influenza:
  • Caused by a group of myxoviruses.
  • Symptoms include fever, chills, cold, cough, and headache.
  • Transmitted through coughing, sneezing, and droplet infection.
  • Prevention includes avoiding contact with patients, vaccination, and wearing masks.
• Measles:
  • Caused by the Rubella virus, it's a highly infectious viral disease.
  • Symptoms include pink or red rashes or red papules appearing around the 3rd day after fever onset, starting behind the ear and on the face, then spreading downwards and covering the whole body within two days.
  • Within a week, the rash fades away leaving brown colored spots.
  • Other symptoms include moderate to high fever, dry cough, and running nose and eyes before the rash appears.
  • Fever falls after the rash appears.
  • Infectious 4 days before and 5 days after rash appearance, mainly transmitted through coughing and sneezing, common in winter.
  • Vaccination is an effective preventive measure.
• Dengue:
  • Caused by the Barbovirus (dengue virus).
  • Symptoms include severe muscle and joint pains, making the patient incapable of movement.
  • A red colored rash may appear on the 4th to 6th day of illness, starting on the hands and legs, and then spread to the rest of the body except the face.
  • Platelet count decreases, and when it falls below 20,000 bleeding complication like hemorrhage may develop.
  • Man is the reservoir of infection.
  • Transmitted via Aedes aegypti mosquito, which bites during the daytime.
  • The mosquito becomes infected while feeding on patient blood during the first three days of illness.
  • Mosquito does not transmit the disease until 11 days have elapsed after the infected blood meal.
  • At the end of this period, the mosquito is capable of transmission.
  • Prevention involves controlling the Aedes aegypti and its larvae by eliminating breeding sites in discarded bins, broken bottles, flower pots, etc. and using larvicidal and insecticidal sprays.
  • Awareness to the masses is another preventive measure.
  • Also known as break-bone fever.
• Chikungunya:
  • Caused by the Alpha virus.
  • Symptoms include fever, severe joint pain that can last for several months, muscle pain, headache, nausea, and rash.
  • Transmitted by infected Aedes mosquitoes that bite during the daytime.
  • Mosquito breeds in stagnant water.
  • Not a contagious disease, as infected person can not spread the infection directly to other person
  • There is no vaccine to prevent or medicine to treat chikungunya virus infection.
  • Prevention includes spraying possible water sources, using mosquito traps and nets, and introducing Gambusia fish in ponds or other water bodies to consume mosquito eggs and larvae.
• AIDS (Acquired Immuno Deficiency Syndrome):
  • Caused by the Human Immuno deficiency Virus (HIV).
  • Symptoms include severe weight loss, decreased blood platelet count causing blood loss, severe damage to brain leading to loss of memory and ability to think and speak, and susceptibility to other infections due to the breakdown of the immune system.
  • HIV can be transmitted through sexual contact, blood transfusion, mother to child during delivery, contaminated needles, syringes, blades or razors and through cuts and wounds during close contact.
  • Prevention includes mass education, using sterile needles, HIV-negative blood for transfusions, avoiding multiple sexual partners and use of condoms, and avoiding sharing razors.
  • There is no effective treatment for AIDS.
• Malaria:
  • Caused by Plasmodium (a protozoan).
  • Symptoms include chills, shivering, high fever with headache, and profuse sweating as fever subsides.
  • Transmitted by female Anopheles mosquitoes.
  • Prevention includes using insect nets and repellents.

Additional Information

• Pathogens are disease-causing biological agents like viruses, bacteria, fungi, protozoa, worms, etc.
• Vectors are carriers of specific germs, such as the female Anopheles mosquito for Plasmodium.

Disease Prevention and Control

• Personal hygiene involves activities that promote health and prevent diseases.
• Proper sanitation and safe, clean water supply are crucial.
• Insecticide sprays prevent mosquito breeding.
• Immunization (vaccination) protects against diseases.
• Health education promotes awareness and prevention practices.

Diet Considerations

• Consume freshly prepared food and avoid stale food.
• Store perishable items properly at low temperatures.
• Boil and filter drinking water, especially if contamination is suspected.
• Avoid excessive consumption of fast foods or junk foods.
• Food must be kept in clean utensils and properly covered to avoid contact with insects and flies.

Lifestyle Factors

• Enough sleep and regular exercises are necessary for maintaining good health.
• Harmful lifestyle habits:
  • Long hours of continuous table work.
  • Lack of physical activities.
  • Excessive screen time.
  • Lack of recreation and sports activities.
  • Smoking, alcohol and drugs.
  • Reading in dim or very bright light.
• Good lifestyle habits:
  • Proper rest and sound sleep.
  • Sufficient physical activity.
  • Timely intake of food with proper nutrition.
  • One must adopt good lifestyle habits and discourage poor lifestyle habits.

Cleanliness

• The basic aim of keeping the body clean is to keep the bacteria and harmful microorganisms away from entering the body or infecting the food consumed.
• Wash hands with soap and water before and after meals.
• Clean teeth after each meal and before bed.
• Take bath regularly with clean water.
• Keep nails short and clean.
• Change clothes daily and avoid tight clothing.
• Maintain clean toilet habits and avoid open defecation.
• Keep garbage in covered bins.

Vaccination and Immunization

• Vaccination is a method of making the body immune to a particular disease.
• It is the administration of a vaccine to stimulate a person’s immune system to develop immunity against the disease causing organism (pathogen).
• Edward Jenner developed vaccination in 1798 as a result of a twenty-six-year study of cowpox and smallpox.
• Immunization is the process by which a person is made immune or resistant to an infectious disease, typically by the administration of a vaccine.

Natural Defense Mechanisms

• Skin acts as a barrier.
• Hair and mucus in the nose prevent entry of dust and microorganisms.
• Antibodies are proteins that attack foreign bodies and protect the host from disease.
• Acid in the stomach kills microorganisms.
• Saliva and tears contain lysozyme, which kills germs.
• White blood cells destroy microbes by engulfing them.
• The immune system produces antibodies to destroy microorganisms.
• TAB vaccine is for typhoid.
• Salk’s vaccine is for Poliomyelitis.
• BCG vaccine is for tuberculosis
• OPV Vaccine is for Polio
• DPT is for Diphtheria

Immunity

• Is the power of the body to resist infections as provided by the immune system.
• Natural immunity is inherited from parents.
• Acquired immunity develops after having and recovering from a disease.

Discovery of Vaccine

• Edward Jenner discovered vaccination after observing that milkmaids who had cowpox did not catch smallpox.
• In 1798, Jenner inoculated children with cowpox, and they did not catch smallpox when later exposed.
• Pasteur also demonstrated the principle of immunisation through his work on fowl cholera.
• Artificial immunity can be provided to children by injecting specific vaccines for protection against diseases.

Types of Vaccines

• Vaccines can contain killed germs (TAB, Salk’s, Rabies vaccines).
• Vaccines can contain living weakened germs (MMR, BCG vaccines).
• Vaccines can contain toxins secreted by pathogens (Tetanus, Diphtheria toxins).

Differences Between Vaccination and Immunization

• Vaccination is the administration of a weakened or inactive germs to stimulate the immune system to develop resistance against the pathogen.
• It is the process of administering a vaccine.
• Immunization is the process by which a person becomes immune to a disease after receiving a vaccine.
• It is the process of making a person immune to a particular disease.

Harmful Substance Use

• Tobacco is obtained from the leaves of Nicotiana which contains nicotine.
• Tobacco contains nicotine, and tobacco smoke contains carbon monoxide, polycyclic aromatic hydrocarbons, and tar.
• Carbon monoxide reduces the oxygen-carrying capacity of the blood.
• Smoking or chewing tobacco increases lung and oral cancer risk, blood pressure, heart disease risk, and causes cough, irritation, ulcers, anxiety, constricted blood vessels, high cholesterol, loss of appetite, and wrinkled skin.
• Even non-smokers in vicinity to active smokers suffer from the symptoms of smoking, which is known as passive smoking.
• Alcohol affects mental and physical activities, lowers blood sugar which has harmful effects on the brain, causes hypertension, damages the liver as alcohol gets stored in it in the form of fat, impairs judgement, reduces self-control and coordination, and affects vision and alertness.
• Drug addiction leads to physical and mental dependence, altering behavior, consciousness, and perception.
• These drugs are collectively called narcotic drugs or psychotropic drugs.
• Drugs may be taken orally, or inhaled, or taken through injections. Some common drugs include opium, morphine, heroin, charas, ganja, bhang, hashish, cocaine and caffeine (very mild narcotic).
• Symptoms of drug addiction include loss of appetite and weight, loss of interest in daily routine work, tremors, unclear vision, nausea, vomiting and body pain, laziness, mood changes, impaired memory, and incoherent speech, and emotional detachment.

First Aid Measures

• First-aid is care given to an injured or sick person before medical treatment.
• Some minor injuries or self-limiting illnesses may only require first-aid, and no further treatment.
• Cuts:
  • Clean the cut with warm water for about 5 minutes.
  • Remove any foreign matter carefully with sterile gauze, cotton swabs or sterile tweezers.
  • After the blood flow stops, put a bandage around the wound.
• Burns:
  • First-degree burns: red and hot, with swelling and pain, but no blisters.
  • A first-degree burn heal on their own. An ordinary sunburn is an example of first-degree burn.
  • Second-degree burns: more severe, red to slightly whitish in color, moist skin with blisters.
  • Third-degree burns: deep, involving the full thickness of skin, white to black or charred, with no sensation.
  • For chemical burns, wash the affected area with running water for 10 minutes and then cover the area with a dry sterile dressing.
• First aid for first or second-degree burns involves holding the burnt area under cold running water for 15 minutes, gently washing it with soap thoroughly, raising the area above heart level, leaving it uncovered unless it is likely to get dirty or get rubbed against clothing, in which case it can be suitably covered, and give the tetanus injection to victim.
• First aid for third-degree burns involves covering the burn with a dry, sterile dressing and contacting emergency services, do not hold the burn under cold water.
• For chemical burns, wash the area with running water and cover with a sterile dressing.
• Bleeding:
  • Raise the affected part to reduce the downward flow of blood due to gravity, wash the cut surface with clean water, press the area with clean cotton pad, and apply some mild antiseptic.
• Fracture:
  • Make the victim lie down comfortably, loosen or remove the clothes from the affected part, and do not move the fractured part.
  • If collar bone is fractured, support the arm on the injured side in a sling.
  • Immobilize the victim, loosen clothes, and support the fractured part.
  • If joint dislocation is suspected, raise and apply ice to the joint. Application of ice packs reduces swelling and helps to reduce pain.
• Unconsciousness:
  • Make the victim lie down comfortably on the bed, loosen the clothes of victim, and let the fresh air enter the room, and switch on the fan.
  • Lay the victim comfortably, loosen clothes, and ensure fresh air.
• Swallowing Poison:
  • Make the victim drink as much salt water as possible.
  • Try to induce vomiting.
  • Make the victim drink salt water and induce vomiting.
• Animal Bites:
  • A pet whose immunisations are up to date is unlikely to have rabies. But even if it bites, observe the animal for 10 days to make sure that it does not develop rabies.
  • Antirabies injections would not be needed by the victim as long as the animals stays healthy after being reliably observed, or if the pet has been immunised up-to-date.
  • In case the bite is from a stray animal, consult a physician.
  • Hold the bite area under cool running water for 5 to 10 minutes.
  • Then wash the area of bite with soap and water and remove any remaining debris with a sterile gauze.
  • Again run water over the bite area for 5 minutes.
  • Then dry the area, and elevate the bite area above the level of the heart.
  • Victim must take antirabies and tetanus injections.
  • Wash the bite area with cool running water and soap, remove debris, and seek medical advice for antirabies and tetanus injections.
• Snake Bites:
  • Remove all rings and bracelets close to the bite and squeeze out blood from the wound.
  • Run water over the bite.
  • Rub powdered potassium permanganate on the bite area.
  • Prevent the poison from being carried to the heart, by putting a piece of string or tape or handkerchief (tourniquet) tightly around the area.
• Insect Stings:
  • Remove the sting with tweezers or scrape across the skin with a metal object having blunt ends.
  • Wash the area with soap and cold water, apply vaseline or oil, then cover it with sterile gauze and put an adhesive tape.
  • If there is swelling, apply ice.
  • Remove the sting, wash the area with soap and water, apply vaseline or oil, cover with sterile gauze, and apply ice if swelling occurs.