1. Ch39: Effect of Disease Higher Human Biology

2. Disease Disease = an impairment of the normal functioning of part (or all) of the body. Caused by: Pathogenic (disease-causing) micro-organisms Deficient diet Stress

3. Regulatory Effect on a Population The growth rate of a population is regulated by disease. If the population density gets to high, disease acts as a limiting factor causing the population to decrease – thus keeping the population in check (at its capacity). Dense populations are more likely to be attacked by disease-causing organisms, if it is fatal this will cause a high death rate.

4. Disease & Human Population Examples of diseases that have had (or could have) a regulatory effect: Bubonic plague (Black Death) 13 th –19 th Century Europe caused by a pathogenic bacterium One epidemic in 14 th century killed 25% HIV (and AIDs) View the Scholar animation: http://courses.scholar.hw.ac.uk/vle/scholar/session.controller?action=view Content&contentGUID=1a112130-bbaa-de2c-a567-99d7ce1d69d4 http://courses.scholar.hw.ac.uk/vle/scholar/session.controller?action=view Content&contentGUID=1a112130-bbaa-de2c-a567-99d7ce1d69d4

5. What is the difference between immunisation & vaccination? Immunisation = the process that increases people’s ability to resist a disease-causing organism. Vaccination = a method of immunisation that deliberately introduces a weakened or altered form of the pathogen (or virus) into the body so that the body can make antibodies against the antigen thus allowing the body to develop immunity to it.

6. Smallpox In 1976, Edward Jenner immunised a boy against smallpox using cowpox virus as a vaccine. Many years later scientists have discovered how to produce vaccines for specific diseases 1840s Britain – free vaccination against Smallpox 1850s Britain – all babies vaccinated 1967 – World Health Organisation (WHO) introduced programme to eradicate Smallpox – completed in 1977

7. Smallpox Eradication Worked because: Passes from human to human – NO animals can carry the disease Immunity from vaccination lasts for long time Single antigen involved so easier to produce a vaccine Able to vaccinate babies just after birth Homed in on fresh out-breaks vaccinating all suspected contacts

8. Malaria difficult to eradicate ….because: …. So it resists eradication & exerts a regulatory effect on the human population. Vaccines only effective against one form of the pathogen Many strains with different composition of antigenic proteins on their surfaces Is carried by mosquitoes – has 2 hosts Changes from one form to another – 3 phases

9. Control of childhood diseases Developed Countries Caused death 150 years ago: measles whooping cough diphtheria tetanus polio tuberculosis Vaccinations & higher standard of living have brought them under control. Vaccination targets of at least 95% are needed to provide protection for the population as a whole.

10. Control of childhood diseases Developing Countries Child mortality from vaccine-preventable diseases is still very high. In 1974 – WHO launched their Expanded Program of Immunisation (EPI) to increase the vaccination of children against the 6 main common childhood diseases. Lack of… understanding information money Parents don’t bring children to be immunised or only get 1 st dose Children remain susceptible & die

11. Improved Hygiene, Sanitation & Living conditions: Developed Countries Changing social & economic factors Improved living conditions Increased resistance to disease Vaccination & health care Modern epidemics (e.g. flu) are on a small-scale due to… advanced warnings vaccination for vulnerable healthier population Minor outbreaks (e.g. cholera) are quickly contained hygiene waste disposal nutrition

12. No sewage disposal Improved Hygiene, Sanitation & Living conditions: Developing Countries In more than 50% of developing countries the majority of the population: No clean water

13. Improved Hygiene, Sanitation & Living conditions: Developing Countries Water contaminated by sewage contains pathogens that cause diseases (e.g. cholera & dysentery) = Diarrhoea most serious 50% deaths in children under 5 80% diseases in poor countries = water-related Need…. Mains sanitation Vaccination Adequate diet Clean drinking water