Non-Infectious Disease

Epidemiology

•Epidemiology is the study of the factors determining and influencing the frequency and distribution of diseases (both infectious and non-infectious)

•Epidemiologists usually work for Government Health Departments and tend to study groups of people rather than actual individuals in order to determine the number of people suffering from a disease and any possible causes of a disease. The aim is to gain enough data in order to prevent and control the disease.

•Health programs can be evaluated and improved when more knowledge is gained. For example high risk patients (the aged, aboriginal, drug addicts or people from low socioeconomic groups) can be identified and assisted.

•A pandemic is a disease that affects many countries and an epidemic is a disease that affects only a certain area.

Epidemiology•There are 3 main types:

•Descriptive studies provide information about the disease, including factors that influence it. For example, for people who suffer from heart attacks information is collected on the age, sex, smoking habits, diet, drinking and eating habits, occupations and family history of the disease.

•Analytical studies set up a hypothesis based on the data gleaned from the descriptive study. Here the scientists can try to predict which factors are more likely to cause the disease.

•Intervention studies aim to change the course of a disease that threatens society.

•Epidemiologist can gather information by conducting case studies, cohort studies or by undertaking randomized trails from the general population.

Nutritional Diseases•The type of nutritional disease depends on a particular dietary deficiency. Nutritional disease are more common in developing countries where people lack resources and conditions to grow fresh food.

•Mineral Deficiencies: Goitre (enlarged thyroid gland) occurs with the lack of iodine.

•Vitamin Deficiencies: Scurvy is one of the most famous diseases caused by the lack of vitamin C. Rickets are caused by deficiency of Vitamin D. Beri Beri is caused by the lack of one of the B group vitamins, Thiamine.

•Protein Deficiency: Kwashiorkor disease is prevalent in children who do not eat enough protein.

•Anorexia and bulimia are also considered nutritional diseases.

http://www.edu.rcsed.ac.uk/photoalbum/ph36.htm

Nutritional Diseases - Scurvy•Cause: Deficiency of Vitamin C.

•Characteristics: In the past scurvy was common amongst sailors who were out at sea for long periods of time and did not have access to fresh fruit and vegetables. Captain James Cook overcame this problem in the late 1700s by introducing limes into the diets of his crew. For this reason the sailors became known as ‘limeys’. Scurvy is still a threat in developing countries where people’s diets lack fresh fruit and vegetables.

•Symptoms: Vitamin C is necessary for the development, growth and repair of connective tissue. Lack of vitamin C leads to sores and bleeding from the gums, fragile capillaries, bruising, poor wound healing and failure of bone marrow to grow.

www.derweb.co.uk/main/ handout7.html

www.healthsentinel.com/

Nutritional Diseases - Scurvy•Treatment: Humans cannot make or store vitamin C so they must have a diet that supplies daily doses by eating lemons, oranges, limes, kiwi fruit, tomatoes (or vitamin C tablets).

•Prevention: Similar to treatment – daily intake of vitamin C through fresh fruit and vegetables, plus education programs about the importance of a balanced diet.

Environmental Diseases•Environmental diseases are those caused by certain lifestyles or by something in the environment such as toxic substances.

•To some extent they are diseases that can be controlled by a persons choices such as using unleaded petrol in order to avoid lead poisoning.

•People can also change their lifestyles such as quitting smoking or reducing binge drinking sessions.

•A person can avoid toxic substances if they are aware of their presence and dangers. Sometimes they find out about the dangers when it is too late, such as with asbestosis.

Environmental Disease - Minamata•Cause: If a person eats too much fish they can intake large quantities of methyl mercury that has been bioaccumulated in the food chain (after dumping of industrial waste mercury into the ocean).

•Characteristics: In 1956 Minamata disease was first described in Minamata Bay in the South Island of Japan. Since then, thousands have died.

•Symptoms: Sensory loss, tremors, ataxia (uncontrolled movement) and both hearing and visual loss. Mercury can cross the placenta and harm the unborn baby inducing mental retardation.

•Treatment: There is no cure for the Minamata Disease. Once the central nervous system is damaged by organic mercury, there is no medical procedure that can reverse the destructive processes that has taken place. Patients can be given support to help cope with the symptoms.

•Prevention: Environmental Ministries around the world are learning from what has happened in Minamata – Japan.

Inherited Disease•Inherited diseases result from mutations in germ-line DNA or changes in chromosomes that are passed on from one generation to the next.

•When a mutation occurs in the DNA, faulty enzymes are produced that cannot carry out their normal function. Point mutations occur when there is a mistake in one base pair (for an example see the ‘Introduction to DNA’ ppt)

•Chromosomal disorders result from a variety of changes in the karyotype of a person. People can have the wrong number of chromosomes (polyploidy), such a one less chromosome as seen in Turner syndrome, or one extra chromosome such as seen in Down syndrome.

•Each of the chromosomes can also exchange parts of themselves with other chromosomes (translocation), have certain parts of the chromosome turned upside down (inversion), repeated (duplication) or missing completely (deletion). All these events result in genetic changes in the individual.

Inherited DiseaseA normal female karyotype: 46,XX

Cri du Chat karyotype: 46,XX,del(5p)

Inherited Disease

Turner Syndrome karyotype: 45, X

Most of these females are sterile, but if they were able to have children, what percentage of their offspring would be normal?

Inherited Disease

Down Syndrome or Trisomy 21

karyotype: 47,XY,+21

Inherited Disease – Down Syndrome•Cause: When a person has 3 copies of chromosome 21 in the nuclei of their cells. An individual can gain an extra chromosome 21 by either a translocation of chromosome 21onto another chromosome, or by non-disjunction.

•Characteristics: This disease has been associated with increased maternal age. The older the mother, the greater the chance of having a child with Down syndrome.

•Symptoms: Flattened nose, slanted wide set eyes, sagging mouth with protruding tongue, mental retardation, reduced life expectancy, single palmer crease, heart defects. Symptoms vary greatly from patient to patient.

Inherited Disease – Down Syndrome

•Treatment: As there is no cure for Down syndrome each patient can been assisted in relation to their particular needs. Early intervention programs have been shown to raise the intellectual achievement of these individuals.

•Prevention: Amniocentisis and chorionic villus sampling removes fetal tissue while the child in still in the uterus. A karyotype can be made from this tissue and if the unborn child has Down syndrome the parents can opt for a therapeutic abortion.

Inherited Disease – Non-disjunctionNon disjunction during meiosis

http://www.med.uiuc.edu/m1/genetics/tutorial1/meiosis_8.htm

Inherited Disease – Non-disjunction

www.irn.pdx.edu/~newmanl/ moviepage.html

Inherited Disease – Down Syndrome by translocation

http://cai.md.chula.ac.th/lesson/down_syndrome/contents/q08a.htm

References•Arisandi, P. (2002) SEVEN THINGS TO KNOW ABOUT MINAMATA DISEASE. Retrieved from http://www.terranet.or.id/masukandetile.php?id=1349 June 2004.

•Aubusson, P. and Kennedy, E. (2000) Biology in Context. The Spectrum of Life Oxford University Press, Melbourne, Australia.

•Board of Studies (2002) STAGE 6 SYLLABUS Biology Board of Studies, NSW, Australia.

•Mudie, K. et.al. (2000) Heinemann Biology Malcom Parsons, National Library of Australia, Australia.

•Humphreys, Kerri (2002) The Search for Better Health. Science Press, Australia.

•Kinnear, J and Martin, M (2001) Biology 2 HSC Course: Jacaranda HSC Science John Wiley & Sons, Australia, Ltd.

•Royal College of Surgeons (2003) Retrieved from http://www.edu.rcsed.ac.uk/photoalbum/ph36.htm June 2004.

•Saker, E., Odlum, C. & Gerner, R. (1988) Human Disease Sofima, PTY, LTD, Sydney

•The Medical House (2003) DerWeb Ltd. Retrieved from www.derweb.co.uk/main/ handout7.html June 2004.

•The Arc of Maryland ( 2001) Down Syndrome Coalition of Maryland. Retrieved from http://www.thearcmd.org/Programs/Down_%20Syndrome/downsyndromecoal.htm June 2004.