A Search For Better Health Topic 11: Epidemiology

1. A Search For Better HealthTopic 11: Epidemiology Biology in Focus, HSC Course Glenda Childrawi, Margaret Robson and Stephanie Hollis

2. DOT Point(s) identify causes of non-infectious disease using an example from each of the following categories: •inherited diseases •nutritional deficiencies •environmental diseases

3. Introduction Non-infectious diseases are those diseases that are not caused by a pathogen and are not contagious. There is a huge range of non-infectious diseases and their causes are many and varied. web2.newtown-h.schools.nsw.edu.au

4. Introduction Historically, infectious diseases were the main cause of death in the world and, indeed, in some developing regions this may still be the case. With the development of antibiotics and vaccination programs, infectious disease is no longer the leading cause of death in the Western world. www.amta.org.au

5. Introduction • Non-infectious disease is now responsible for the leading causes of death in both developed and some developing countries. This table shows that the leading causes of death in Australia in 2009 are all non-infectious diseases. Cancer is the leading cause of death. www.couriermail.com.au

6. Introduction Non-infectious disease includes inherited diseases caused by changes in genetic information, nutritional deficiencies caused by an inadequate diet, and environmental diseases that are the result of factors in the environment. Other diseases such as those caused by some types of physiological malfunction, some mental illnesses and ageing will not fit into these categories. window20.com

7. Inherited Diseases These are diseases that are genetically transmitted and are caused by errors in genetic information. These errors may include: • a change in the chromosome numbers. For example, Down syndrome is caused by an extra chromosome 21 and Klinefeltersyndrome is caused by an extra X chromosome. www.couriermail.com.au

8. Inherited Diseases • a defect in a single gene caused by mutation. Diseases caused by gene abnormalities include cystic fibrosis, haemophilia, thalassemia and phenylketonuria (PKU). www.mun.ca

9. Inherited Diseases Cystic fibrosis is an example of an inherited disease that is caused by a mutation to the cystic fibrosis transmembraneconductance regulator (CFTR) gene that is found on chromosome 7. This faulty gene changes the protein that regulates the normal movement of sodium chloride in and out of cells. This causes the mucus-secreting organs to produce abnormally thick mucus. www.pathology.org

10. Inherited Diseases The CFTR gene is recessive, meaning that a person must have two copies of the faulty gene for them to develop the disease. The occurrence of cystic fibrosis varies with ethnic groups. www.babycenter.com.au

11. Inherited Diseases Cystic fibrosis affects the respiratory, digestive and reproductive systems, as well as the sweat glands. The mucus secreted is very thick and blocks passageways in the lungs and digestive tracts. This mucus causes problems with breathing and with the digestion and absorption of nutrients. www.drugs.com

12. Inherited Diseases Some of the symptoms of cystic fibrosis are: • recurrent and severe chest infections • malabsorptionof nutrients and failure to thrive • passing of large, foul-smellingmotions • Diabetes • excess salt in sweat • liver failure • infertility. The average life expectancy of someone suffering from cystic fibrosis is 30–40 years. journeys4good.com

13. Inherited Diseases The treatment of cystic fibrosis involves relieving the symptoms as there is at present no cure for the disease. This treatment allows sufferers to better cope with cystic fibrosis in their daily lives. Treatments include giving supplements to their diet to counter the effect of insufficient digestion and absorption of nutrients. blog.23andme.com

14. Inherited Diseases Sufferers use daily physiotherapy and breathing exercises to help prevent the excessive build-up of mucus in their lungs. This also helps to prevent chest infections. Antibiotics and other medications are given to treat and control the many infections that develop. If the lungs are too badly damaged then lung transplantation could be an option. Gene therapy is currently being researched in the hope that it will eventually be able to cure cystic fibrosis. app1.unmc.edu

15. Nutritional Deficiencies Nutritional deficiencies can be caused by diets lacking the proper balance and amount of nutrients. They can also be caused by psychological conditions that lead to inappropriate diets. www.guardian.co.uk

16. Nutritional Deficiencies A diet that is lacking a vital nutrient, usually a vitamin or a mineral, can lead to a nutritional deficiency. Some examples of these diseases include: • anaemia, which causes lethargy, and results from a lack of iron or folic acid • beri-beri, which results in retarded growth, weakened heart muscle, digestive disorders and muscle atrophy (wasting), and is caused by a lack of vitamin B1 agritech.tnau.ac.in

17. Nutritional Deficiencies • reduced metabolic rate, low body temperature, puffiness around the eyes, protruding eyes and goitre, all caused by insufficient iodine • kwashiorkor, caused by a deficiency in protein and resulting in a failure to grow, swelling of tissue, enlarged liver, hair changes, apathy and irritability. healthinq.blogspot.com

18. Nutritional Deficiencies Diseases that have a psychological basis and result in behavioural disorders that lead to an inappropriate diet include such conditions as anorexia nervosa, bulimia and obesity. familymedicinehelp.com

19. Nutritional Deficiencies Scurvy is a nutritional deficiency disease that results from a lack of adequate amounts of vitamin C in the daily diet. It was typically associated with sailors in the 1700s and has been known to cause more deaths at sea than storms, shipwreck and combat. www.chacha.com

20. Nutritional Deficiencies Vitamin C (ascorbic acid) is important in many biological functions in the body, especially in the production of substances required for connective tissue, bones and dentin. A deficiency in vitamin C weakens the blood capillary wall, leading to bleeding and bruising. drugline.org

21. Nutritional Deficiencies Initial symptoms of scurvy include: • pain and tenderness in the legs • swelling of the long bones • swollen, purplish and spongy gums. www.nejm.org

22. Nutritional Deficiencies More advanced symptoms include: • gangrene (degeneration of tissue) • reopening of old wounds • spontaneous haemorrhaging • purple/black spots on the skin, indicating haemorrhaging • separation of once-healed broken bones • bleeding of the membrane covering the front of the eyes or the eyelids. If scurvy is left untreated for an extended period of time, death will result.

23. Nutritional Deficiencies Scurvy is rarely seen in developed countries except in people with poor diets or unusual food habits. It is more commonly found in developing nations where fresh fruit and vegetables, which act as rich sources of vitamin C, may not be available. Scurvy can occur in people of any age, with the risk groups being infants, the elderly and alcoholics. www.bubblews.com

24. Nutritional Deficiencies The treatment of scurvy is very easy and simply involves the inclusion of adequate amounts of vitamin C in the diet. For more serious cases, supplements of vitamin C should be taken daily. In order to prevent the occurrence of scurvy, adequate amounts of vitamin C should be included in the daily diet. www.freshforkids.com.au

25. Environmental diseases There are many different types of environmental disease, including: • lifestyle diseases such as cardiovascular disease, diseases caused by substance abuse such as alcoholism, and smoking-related diseases • diseases caused by physical factors in the environment, such as skin cancer caused by excessive exposure to ultraviolet radiation in sunlight sienna-x.co.uk

26. Environmental diseases • diseases caused by exposure to chemicals in the environment, such as lead poisoning caused by exposure to high levels of lead in the atmosphere from pollution or lead-based paints. Exposure to asbestos can result in the fatal disease mesothelioma. www.apheda.org.au

27. Environmental diseases Mesothelioma is a cancer of the mesothelialcells that occur in the pleura membrane on the outside of the lung. Mesothelioma grows in the pleural space surrounding the lungs and the tumour may eventually surround the entire lung. learningradiology.com

28. Environmental diseases The initial stage in the development of cancer involves a mutation to a gene that is involved with the normal process of cell division. This mutation causes the process of mitosis to be affected and can result in the uncontrolled division of cells, leading to cancer. At this stage it is not known what causes the mutation that can lead to mesothelioma, but it is known that a high risk factor is exposure to asbestos fibres. www.housecalls.net.au

29. Environmental diseases When asbestos fibres are inhaled, most of them stick to the mucus inside the respiratory passages and are coughed up or swallowed. The long, thin fibres of asbestos are not easily cleared like this and may reach the ends of the small airways and penetrate the pleural lining of the lung and the chest wall. It is these fibres that in some way damage the cells and are thought to cause the mutation that leads to mesothelioma. www.mesotheliomaattorneyslawfirm.org

30. Environmental diseases The risk of developing mesothelioma is directly linked to the quantity and length of exposure. Mesothelioma can take 20 to 50 years to develop after exposure to the asbestos. The incidence of mesothelioma in Australia is 40 cases per million people and is the highest in the world. Other countries that have mined and used asbestos have slightly lower rates of occurrence of the disease. mesotheliomawives.wordpress.com

31. Environmental diseases The symptoms of mesothelioma include shortness of breath caused by the tumour squashing the lungs, chest pain and, in the later stages of the disease, weight loss, loss of appetite, fatigue, fevers, night sweats and anaemia. arca-med.com

32. Environmental diseases Mesothelioma is usually incurable by the time it is diagnosed, so treatment is aimed at controlling the symptoms and extending the life of the sufferer. It is almost impossible to remove the tumour surgically. Relief from the symptoms caused by the squashing of the lungs can be achieved using surgery to insert chest tubes to drain off the excess fluid. www.kazanlaw.com

33. Environmental diseases Traditional radiotherapy is not successful as it damages normal lung tissue. Chemotherapy has not proven to be very successful until recently when new combinations of drugs have been trialled. Research into new types of treatment is continuing, with the emphasis on immune system therapies. www.asbestos.com

34. Homework -NIL-work on your assessment task!!