Effect of disease Chapter 39

Disease on a population Disease – impairment of normal body function Caused by – pathogens, poor diet, stress Disease acts a limiting factor – has a regulatory effect Not as serious an effect as before (‘Black Death’) HIV potentially as damaging

HIV statistics

Use of vaccines Immunisation – increasing a persons resistance to a disease Vaccination – deliberate introduction of an altered pathogen to help immunity Smallpox: Completely eradicated, because… Spread through direct human contact only (no other hosts) Immunity from vaccination is long term Virus has only 1 antigen, easy to make a vaccine Most diseases change too quickly for vaccination - still have a regulatory effect

Control of childhood diseases Developed countries: most diseases controlled by vaccinations etc. e.g. measles, whooping cough, diptheria, tetanus, polio, TB Governments have minimum targets (95%) & immunisation schedules Developing countries: Despite initiatives (e.g. EPI) many millions die of the same diseases Lack of info, money etc prevent children being immunised properly

Hygiene, sanitation & living conditions Developed countries: Social & economic factors help reduce disease mortality E.g. hygiene, waste disposal, nutrition Epidemics prevented by – advance warnings increased vaccine availability general good health Developing countries: Lack of clean water, sewage disposal etc. Contaminated water = 80% of diseases (e.g. diarrhoea) - clean water, sanitation etc are badly needed