Oracabessa High School



SECTION D: DISEASE AND ITS IMPACT ON HUMANSSPECIFIC OBJECTIVES EXPLANATORY NOTESStudents should be able to:1. define the terms good health and diseaseWHO definition which relates to physical, mentaland social well-being and not just the absence ofdisease.2. classify diseasesCommunicable (infectious diseases) and noncommunicable diseases (chronic or degenerativedisease, nutritional deficiency disease, inheriteddisorders).3. differentiate between the terms signs and symptoms4. state the main causes, primarysymptoms and possible treatment ofasthma5. explain how asthma affects the respiratorytract6. discuss the causes, signs/symptoms, treatmentmodality and prevention of chronic/lifestylerelated diseases;(a) Obesity, diabetes mellitus (type I and typeII) and cardiovascular disease (hypertensionand coronary heart disease).(b) Diabetes mellitus (type II) and secondaryhypertension as complications of obesity.(c) The importance of diet and exercise.7. discuss the causative agent, signs, symptoms,prevention and control of infectious diseasesAcute respiratory infection (influenza, bronchitis,pneumonia), sexually transmitted infections (STIs)(gonorrhea or syphilis, herpes), ringworm,typhoid, tuberculosis, cholera, gastroenteritis.8. discuss the cause, symptoms, mode of action,prevention and control of HIV/AIDS.Include method of transmission, methods of limitingspread/prevention and possible treatment ofHIV/AIDS (anti-retroviral drugs - side effects).9. describe the effects of sexually transmittedinfections (STIs) on the pregnant motherand the foetus10. discuss the impact of diseases on the humanpopulationSocio-economic implications, analysisHealthHealth is defined by the World Health Organization (WHO) as a state of complete physical, mental and social well-being.Mental health means having a healthy mind free form depression and worry.Social well-being means having satisfactory relationships with other people and a good attitude on life in general.DiseasesDisease is the loss of health brought about by an association between the person (host) and a disease agent (cause).Types of diseaseAgents responsible for disease1. InfectiousPathogens e.g. Viruses, bacteria, fungi, protozoa, worms2. DeficiencyMalnutrition, lack of nutrients e.g. vitamins and minerals3. MentalAnxiety, stress and depression4. DegenerativePhysiological defect e.g. diabetes, coronary heart disease, cancer, ageing5. Inherited/geneticInheritance of harmful genes e.g. albinism, downs syndrome, sickle cell anemia6. Physical injuryAccident e.g. limb damage7. PoisoningIngesting poisons e.g. toxins from bad meat8. Self-inflictedBy smoking, drug taking, pollutionInfectious diseases are caused by pathogens. A pathogen is an any organism that causes a disease. The main pathogens are microorganisms. Pathogens are transmitted to humans by vectors. Vectors are insects or some animals that carry pathogens to the human body. Air, water and food can also pass on pathogens.Non-transmissible or non-communicable diseases are not caused by pathogens but they are passed on from one person to another. Degenerative diseases are caused by a breakdown of the body tissues preventing them from working properly. Most degenerative diseases are chronic and chronic diseases are long lasting and non-communicable, where there is no complete cure.Signs and symptoms Diseases are detected by signs and symptoms. Symptoms are felt by the patient e.g. pain, headache while signs are those that can be seen by an observer e.g. spots (rashes), swellings etc. Asthma Asthma is a disease that affects the respiratory system. When a person has asthma the bronchial tubes constrict and inflammation may occur. The causes of asthma include; inducers such as allergens (house dust mites, pollen, pets’ fur and feathers, virus infections) and triggers such as smoke, airborne irritants, cold air, stress, excess exercise and it may also be inherited. Symptoms include increased mucus secretion that blocks the airways, shortness of breath, inflammation of bronchial tubes, tightness in the chest, coughing and wheezing. Treatment of asthmaAsthma can be treated with inhalers to prevent constriction and inflammation of bronchial tubes. Corticosteroids and antihistamines may be taken. Finding the allergen or another cause of asthma and removing it from one’s environment can also be used to treat the disease.How does asthma affect the respiratory tract?During an asthma attack, the muscles surrounding the airways contract, limiting the amount of air supply to the lungs. The lack of sufficient air supply results in a choking sensation. Asthma attacks induce the?secretion of mucus, which causes the airway to constrict even more, making the asthma attack worse. During an asthma attack the bronchiole contracts (bronchospasm) while the lining expands and fluids build up, further?constricting the airway.Lifestyle DiseasesObesityObesity is a chronic condition defined by an excess amount of body fat. A certain amount of body fat is necessary for storing energy, heat insulation,?shock?absorption, and other functions. Obesity is best defined by using the?body mass index. The body mass index is calculated using a person's height and weight.Causes1. Genetics. A person is more likely to develop obesity if one or both parents are obese. Genetics also affect hormones involved in fat regulation2. Overeating. Overeating leads to weight gain, especially if the?diet?is high in fat. Eating too much foods high in fat or sugar (for example, fast food, fried food, and sweets) can cause obesity.3. A diet high in simple carbohydrates.4. Physical inactivity. Sedentary people burn fewer calories than people who are active.5. Psychological factors. For some people, emotions influence eating habits. Many people eat excessively in response to emotions such as boredom, sadness, stress, or anger6. Medications. Medications associated with weight gain include certain?antidepressants and oral contraceptives.Sign/ SymptomsClothes feeling tight and needing a larger size.The scale showing that you've gained weight.Having extra fat around the waist.A higher than normal body mass index and waist circumference.Treatment/ Prevention1. To lose weight successfully, and to maintain a healthy weight, requires lifelong changes in eating and exercise habits?2. Regular physical activity is an important part of weight management.3. Medications may be part of a weight management program.Diabetes Mellitus Diabetes mellitus (or?diabetes) is a chronic, lifelong condition that affects your body's ability to use the energy found in food. There are two major?types of diabetes:?type 1 diabetes,?type 2 diabetes,Type I- is also called insulin-dependent diabetes. It used to be called juvenile-onset diabetes, because it often begins in childhood. n people with type 1 diabetes, the damaged pancreas doesn't make insulin.This type of diabetes may be caused by a genetic predisposition. It could also be the result of faulty beta cells in the pancreas that normally produce insulin.Treatment for type 1 diabetes involves taking insulin, which needs to be injected through the?skin?into the fatty tissue below. Frequent testing of your blood sugar levels, Careful meal planning and Daily exercise.Type 2- was also called non-insulin-dependent diabetes. With Type 2 diabetes, the pancreas usually produces some insulin. But either the amount produced is not enough for the body's needs, or the body's cells are resistant to it. Insulin resistance, or lack of sensitivity to insulin, happens primarily in fat, liver, and muscle cells.Some of the signs and symptoms of type 1 and type 2 diabetes are:Increased thirst.Frequent urination.Extreme hunger.Unexplained weight loss.Presence of ketones in the urine (ketones are a byproduct of the breakdown of muscle and fat that happens when there's not enough available insulin)Fatigue.Irritability.Hypertension (high blood pressure)CausesSmoking, Being?overweight?or obese, Lack of?physical activity, Too much salt in the diet, Too much alcohol consumption (more than 1 to 2 drinks per day), Stress, Older age, Genetics, Family history of high blood pressureIf your blood pressure is extremely high, there may be certain symptoms to look out for including:Severe headache, Fatigue or confusion, Vision problems, Chest pain, Difficulty breathing, Irregular heartbeat, Pounding in your chest, neck or ears.Treatment- medication, less stress, balanced diet and exerciseCoronary Heart diseaseCoronary heart disease is caused by a buildup of fatty deposits in the walls of the coronary arteries around the heart. Risk factors (Causes) for coronary artery disease include:Age. Simply getting older increases your risk of damaged and narrowed arteries.Sex. Men are generally at greater risk of coronary artery disease. Family history. Smoking. High blood pressure. ...High blood cholesterol levels.Diabetes. Overweight or obesity.Sign and Symptoms- shortness of breath, chest pains, heart attack, heart failure, abnormal heart rhythm.Treatment for coronary artery disease usually involves lifestyle changes and, if necessary, drugs and certain medical procedures.Lifestyle changesQuit smoking.Eat healthy foods.Exercise regularly.Lose excess weight.Reduce stress.Importance of diet and exerciseGood nutrition is an?important?part of leading a healthy lifestyle. Combined with physical activity, your?diet?can help you to reach and maintain a healthy weight, reduce your risk of chronic diseases (like heart disease and cancer), and promote your overall health.Acute respiratory infections: Influenza (air Bourne diseases)1. Influenza is similar to the common cold and it is caused by a virus and through the air. Symptoms include, fever, headache, sore throat and backache. Signs include, raised body temperature, shivering.Treatment include, hot drinks, rest and sleep, painkillers. It can be controlled by avoiding crowds, influenza vaccine and painkillers.2. PneumoniaPneumonia is inflammation of the lungs often occurring when a person is weakened by other infections such as AIDS. Pneumonia is caused by a bacterium and spread by droplet infection through the air. Signs include shivering, raised body temperature and Symptoms include fever, cough, wheezing sound, rapid breathingTreatment include antibiotics such as penicillin3. TuberculosisThis disease is common where there is overcrowding, malnutrition and dirty surroundings. Tuberculosis is caused by a bacterium and it can be spread through the air. The bacterium is called Mycobacterium tuberculosis. The disease mostly affects the lungs but can also affect the bones and lymph glands. In the lungs, phagocytes will engulf the bacteria but the cells are incapable of digesting the bacteria, as they have a wax coating around them for protection. The phagocytes will form a mass around the bacteria and tubercles form on the lungs. Toxins called tuberculins are released which will destroy any cells around them. The tubercles will burst to release the bacteria in the bronchiole tubes. This stage is the highly infectious stage. Signs include; a cough which gets worse as the disease progresses, sufferers become pale and develop a fever, spitting blood and finally death. Symptom- lung tubercles.Control- avoid overcrowding and spittingTreatment- good ventilation, BCG vaccine, mass X-ray diagnosis, antibiotic drug treatment (streptomycin).Activity. Research the causes, signs, symptoms and treatment for bronchitisWaterborne diseasesEntry through infected drinking water.Typhoid, cholera and amoebic dysentery are all intestinal diseases caused by drinking infected water or contaminated food. The organisms causing the disease mainly comes from faeces of other infected people. Proper disposal of faeces and water purification can prevent these diseases. The disease is spread by carriers. Carriers are healthy people who have the disease organisms in their bodies but show no symptoms.1. GastroenteritisTyphoid, cholera and amoebic dysentery all cause gastroenteritis. Gastroenteritis is damage to the walls of the stomach and intestines by inflammation. Pathogens mainly cause damage to the walls or produce toxins or form ulcers that will sometimes bleed. Signs include diarrhoea, sickness and symptoms include abdominal pains.2. TyphoidThis disease is caused by the bacterium Salmonella typhi, which attacks the walls of the intestine and food poisoning will result. The bacteria cause ulcers and death, as the intestinal walls break down. There is a 2-week incubation period followed by the following signs: fever, rash and severe diarrhoea. Control- proper disposal of faeces, chlorination of water, destroy houseflies, hygienic food preparation.Treatment- immunization, antibiotics such as chloramphenicol kills the bacteria.3. Cholera This disease is caused by a vibrio (curved) bacterium, Vibrio chloerae. The causes are drinking untreated water and coming in contact with contaminated faeces. Houseflies are vectors that may transmit the bacteria from their faeces to our food. There is a 1-6-day incubation period, where the bacteria produce toxins in the small intestine.Signs include severe diarrhoea, dehydration then death. Control- proper disposal of faeces, chlorination of water, destroy houseflies, hygienic food preparation.Treatment- immunization, antibiotics such as chloramphenicol kills the bacteria, isolation of the infected person.4. Bacterial dysenteryThis disease is caused by the bacteria Shigella, which is transmitted in food infected by houseflies and contaminated faeces. Signs and symptoms are diarrhoea and stomach pains. A protozoan Entamoeba also causes amoebic dysentery.Sexually Transmitted InfectionsThese are venereal diseases that can only be passed from one person to another during sexual intercourse. 1. GonorrheaGonorrhea is caused by a bacterium (a gonococcus). In women, the warm, moist mucous membrane of the cervix is the place of early infection. The infection will then spread to the oviducts and they will become blocked. In males, inflammation of urethra can spread to the prostate and testes and cause them to become blocked. In both cases sterility occurs.Symptoms- itching, burning sensation when passing urineSigns- in males after 2-10 days a pus discharge comes from the penisArthritis, heart disease, blindness and death may result is left untreated.Treatment- a single large injection of penicillin 2. SyphilisThis disease is caused by a spirochete (large spiral shaped bacterium). After an incubation period of between 1 week to 3 months, a hard-red ulcer grows at the site of the infection. This ulcer heals in a month, then a body rash follows 2 to 4 months later, this means the bacteria have spread to all body organs. These rashes will disappear and many years later, bacteria in the brain cause death and insanity.Treatment- early treatment with penicillin injectionsNon-venereal sexually transmitted diseasesThere are diseases that are mainly sexually transmitted but are not true venereal diseases because they may be caught in other ways. 3. Herpes Genital herpes is caused by the herpes simplex virus, type 2. It starts with an itching, and rash around the genitals and later painful blisters that open to make ulcers. A newborn of a herpes sufferer can be born with nervous complaints, blindness or die at birth.Prevention – avoid contact with the regions of blister or ulcers of infected persons. Symptoms- frequent causes of infertilityCervical cancer- caused by the HPV virus and it can lead to death.4. HIV and AIDSAIDS is caused by a human immunodeficiency virus (HIV). This HIV virus destroys the T lymphocytes, without these lymphocytes he immune response is weakened to destroy bacteria. Dementia, weight loss and other infections will frequently occur. The patient will die from other infections such as pneumonia, cancer or tuberculosis, which are called opportunistic infections.Once the virus enters the blood its binds to a receptor on the T lymphocyte and enters the cell, sheds its coat and then its RNA enters the nucleus and joins the cells’ DNA and remains there. HIV makes the immune system useless. Symptoms- weakened body resistance/immunity, cancer, opportunistic infections, lack of white blood cellsSigns- swollen lymph glands, cough, fever, skin rashesPrevention- wear condoms, limit sexual partners, get tested, don’t do drugsMethods of transmission- heterosexual and homosexual intercourse, drug addicts’ infected needles, blood transfusions, congenital (from mother to fetus)Treatment- blood tests can be used to detect antibodies to the HI virus. Antiviral drugs can be taken 1-3 times per day. HIV is a retrovirus because it uses its RNA to produce DNA in the host cell. Therefore, anti-retroviral drugs can be used to fight it, but there is no cure. Anti-retrovirals have side effect like nausea, weakness etc.Effects of STIs on pregnant women and the fetusThe gonorrhea and syphilis bacteria can cause damage to the fetus and often results in the baby being born dead (stillbirth)Babies can be born with eye defectsHIV can infect babies if it crosses the placenta or in breast milkHerpes can cause blindness in the fetusImpact of diseases on the human populationDiseases have a negative effect on the human population. It causes population decline in some cases as people die from them. As well as, it is quite expensive on both governments and individual, as health care and drugs are expensive. In most cases, the poorer sections of the population will always die, as they do not have the resources to receive and seek treatment.Students should be able to:Specific ObjectivesExplanatory Notes11. discuss the effects of malaria and dengue(strain I - IV) on the human body;Signs and symptoms, causative agent, method oftransmission, prevention/control and treatment.12. explain the effect of vectors on humanhealth;Definition of vectors: rats, mosquitoes,houseflies. Include mode of action.13. describe the life cycle of the mosquito andhousefly;Diagrams required.14. explain the importance and methods ofcontrolling vectors which affect human health;Spread of communicable fatal diseases, leptospirosis, dengue fever, gastroenteritis15. explain how and why personal hygiene ismaintained;Elimination of body odours; social acceptance;prevention of infections; prevention of dentalcarries. Include male circumcism. Care of genetalia.16. explain the methods used to control the growth of microorganisms;(a) Definition of the term sterilization,methods of sterilization (ultra-hightemperature, pasteurization, autoclaving,boiling, canning).(b) Effects of high temperatures, disinfectantsand antiseptics in the control ofmicroorganisms.(c) Disinfection - use of chemical agents(chlorine, disinfectants, antiseptics).17. distinguish between disinfectants andantiseptics;18. explain the use of common antibioticsand antifungal agents;Definition of antibiotics. Antigen, antibody,anti-toxin.Insect-borne diseasesBiting insects as disease vectorsMosquitoes can directly transfer diseases to humans by biting or piercing the skin. Aedes is the species of mosquitoes which transmits the dengue virus, when biting the human skin for blood. Only the female mosquito can bite and infect.Mosquito life cycle: Aedes aegypti1. Mosquitoes require stagnant water such as ponds, ditches or puddles for the development of their egg, larva and pupa stages. The Aedes mosquito breed in towns anywhere stagnant water is found.2. The eggs are laid singly on the surface film of the water. The larvae emerge after a few days and hang down from the undersurface film on the water. The larvae breathe through tubes called spiracles, which are held at the water surface. The larvae filter feeds on small floating food material.3. The larva will then shed its outer coating, called a cuticle in a process known as moulting.4. After 4 moults, the larva forms a comma-shaped pupa. The pupa can flick its abdomen to swim, but still hangs from the surface film of the water, in order to breathe through the spiracles.5. A few days later, the case of the pupa spits along the back of the head and thorax. The adult mosquito climbs out onto the surface film of the water. The outer cuticle of the mosquito hardens before it flies away.The whole life cycle takes between 11 and 15 days. The mosquito life cycle shows metamorphosis because the larval stage differs in shape and form from the adult. The mosquito as a vector for dengue and malariaOnly the female adult mosquito can suck blood. The female has a bushy antenna and the male has a more thread-like antenna. The female is attracted to the human body by the smell of sweat. The mouthparts of the female have long pointed threads that penetrate the skin to reach the blood capillaries. The mouthparts are held in a structure called the labium, which bends to allow the threads to enter the skin. DengueThere are four strains of the virus DEN I to IV and the vector is the Aedes mosquito.Symptoms- these appear 3 to 14 days after infection, as a fever with a frontal headache, abdominal pains, joint and muscle pains.Signs- Vomiting, sickness, with a rash spreading from the torso to areas of the legs and face. The liver enlarges and the circulatory system may fail. Blood clotting and the number of platelets are reduced Method of transmission- Aedes mosquito biting to suck bloodPrevention/Control- prevent adult mosquitoes from biting infected persons, destroy mosquitoes by: killing adults with insecticide spray, killing larvae and pupae by spraying oil on stagnant water, introduce fish, kill larvae with Bacillus thuringiensis (this is a bacterium that multiplies in the gut of the larvae and kills it)Treatment- drugs such as acetaminophen, action to manage fever, take plenty rest and fluids. There is no vaccine.MalariaA protozoan called Plasmodium, which is transmitted by the Anopheles mosquitoes cause the disease. Plasmodium damages the red blood cells and releases toxins which cause fever.Symptom- anaemia, headaches, painsSigns- shivering, sweating with shakingMethod of transmission- Anopheles mosquito biting to suck bloodPrevention/Control- prevent adult mosquitoes from biting infected persons, destroy mosquitoes by: killing adults with insecticide spray, killing larvae and pupae by spraying oil on stagnant water, introduce fish, kill larvae with Bacillus thuringiensis (this is a bacterium that multiplies in the gut of the larvae and kills it)Treatment- drugs such as Quinine, mepacrine, paludrine can be used to kill the parasite plasmodium.VectorsVectors are organisms that carry diseases to humans and other animals. Vectors include: rats, mosquitoes, houseflies. Rats are a menace and the black rat (Rattus rattus) spreads a disease called plague. The bacteria causing the plague are found in the blood of rats. The rat fleas suck up this blood and the bacteria multiplies in the insect’s stomach. The bacteria are found in rat fleas faeces and may enter humans through cuts.In humans, the bacteria cause the lymph glands and vessels to become swollen and tender. This will lead to death, if the bacteria get into the bloodstream. Rats urine and faeces contain the spirochaete Leptospira that causes leptospirosis. Dogs, mice and fleas may act as vectors. The Leptospira enters the body through scratches, food or drink contaminated with rat urine. The disease causes a fever, severe headache, pain in the limbs and jaundice. If the disease is not treated kidney damage, liver failure and meningitis will occur. Houseflies Houseflies lay between 100 and 150 eggs in rotten faeces. Depending on the temperature, eggs hatch into larvae after 6 to 24 hours. The larva feed on organic refuse and moults twice before turning to a pupa. The adult emerges after 14 days and can mate and lay eggs 4 days later. Importance of controlling vectorsFor diseases where there is no effective cure, such as?Zika Virus,?West Nile Virus?and?Dengue fever, vector control remains the only way to protect human populations. However, even for vector-borne diseases with effective treatments the high cost of treatment remains a huge barrier to large amounts of developing world populations. Both prevention through vector control and treatment are needed to protect populations.As the impacts of disease and virus are devastating, the need to control the vectors in which they carried is prioritized. Vector control in many developing countries can have tremendous impacts as it increases mortality rates, especially among infants.?Because of the high movement of the population, disease spread is also a greater issue in these areas.Methods of vector control1. Habitat and environmental controlRemoving or reducing areas where vectors can easily breed can help limit their growth. For example, stagnant water removal, destruction of old tires and cans which serve as mosquito breeding environments, and good management of used water can reduce areas of excessive vector incidence.Further examples for environmental control is by reducing the prevalence of?open defecation?or improving the designs and maintenance of?pit latrines. This can reduce the incidence of flies acting as vectors to spread diseases via their contact with?feces?of infected people.2. Reducing contactLimiting exposure to insects or animals that are known disease vectors can reduce infection risks significantly. For example, bed nets, window screens on homes, or protective clothing can help reduce the likelihood contact with vectors. To be effective this requires education and promotion of methods among the population to raise the awareness of vector threats.3. Chemical controlInsecticides,?larvicides,?rodenticides,?Lethal ovitraps?and repellents can be used to control vectors. For example, larvicides can be used in mosquito breeding zones; insecticides can be applied to house walls or bed nets, and use of personal repellents can reduce incidence of insect bites and thus infection. The use of pesticides for vector control is promoted by the?World Health Organization?(WHO) and has proven to be highly effective. 4. Biological controlThe use of natural vector predators, such as?bacterial?toxins or?botanical?compounds, can help control vector populations. Using fish that eat?mosquito?larvae or reducing breeding rates by introducing sterilized male?tsetse flies?have been shown to control vector populations and reduce infection risks.Personal HygieneHygiene is the various measures a person takes to avoid infection or to maintain cleanliness and ensure good health.Personal hygiene must be maintained to: eliminate offensive body odours, prevent infections, prevent bad breath and dental issues, prevent microorganisms from causing diseases and prevent fungi (athletes foot).Individuals must bathe regularly with soap, wash garments, wash hair with shampoo to remove dirt, brush teeth with toothpaste regularly, use deodorants and remove water from between toes. Under the fingernails and toenails must also be kept clean to prevent passing on germs. The genitalia (penis and vagina) must be washed regularly especially after sexual intercourse. Men should wash under the foreskin and should think about getting circumcised to prevent infections. Circumcision is the surgical removal of the foreskin.Methods used to control the growth of microorganisms1. Sterilization is the complete destruction of all unwanted organisms present in a substance. Methods of sterilization include pasteurization, ultra-high temperature, autoclaving, boiling and canning.2. Pasteurization?is the process of heat processing a liquid or a food to kill pathogenic bacteria to make the food safe to eat. The use of?pasteurization?to kill pathogenic bacteria has helped reduce the transmission of diseases, such as typhoid fever, tuberculosis, scarlet fever, polio, and dysentery. Milk?is an excellent?medium?for microbial growth, and when stored at the right temperature, bacteria and other pathogens grow quickly.Diseases prevented by pasteurization include?tuberculosis,?brucellosis,?diphtheria,?scarlet fever, and?Q-fever. Pasteurization also kills the harmful bacteria?Salmonella.Pasteurization is the reason for milk's extended shelf life. High-temperature, short-time (HTST) pasteurized milk typically has a?refrigerated?shelf life?of two to three weeks, whereas ultra-pasteurized milk can last much longer, sometimes two to three months. Read and make notes from pages 306-308 0f textDisinfectants and antisepticsAn?antiseptic?is used on living tissues and cells to destroy any types of infections which may be living on the tissue.?Disinfectants?are meant to destroy microorganisms which can infect nonliving objects. Common?antiseptics?include mouthwash, and yeast infection treatment creams.Do objective number 18 for your Home work ................
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