Introduction to diseases

• A disease is an illness
• Diseases are caused by pathogens
• Pathogens come in the form of:
• bacteria, viruses, fungi, protozoa(single celled animals) and small worms
• Bacteria can be viewed using a light microscope
• Viruses can only be viewed using special microscopes
• Pathogens feed on other living organisms
• hosts- living organisms on which pathogens live
• contagious diseases- are diseases that can be spread via contact
• infections diseases-those diseases that can be spread by droplet infection
• vectors-organisms that carry pathogens from host to host

How pathogens are transmitted

• By vectors e.g. malaria,sleeping sickness and cholera
• By physical contact e.g. gonorrhoea,leprosy, tetanus, STDs,ringworms etc
• By droplets of water or in the air e.g. tuberculosis TB, influenza (Flu), colds
• By contaminated food e.g. typhoid, malaria, cholera,hepatitis etc

To access more topics go to the Combined Science Notes page