Pathogens
- A pathogen is a disease-causing organism
- Pathogens are passed on from one host to another and therefore the diseases they cause are known as transmissible diseases
- Pathogens can be passed on from host to host in different ways, including:
- Direct contact - the pathogen is passed directly from one host to another by transfer of body fluids such as blood or semen (eg HIV, gonorrhoea, hepatitis B & C)
- Indirect contact - the pathogen leaves the host and is carried in some way to another, uninfected individual
Methods of transmission table
Method of Transmission | Examples of diseases spread in this way |
Droplets in air | Common cold, influenza |
Food or water | Cholera, typhoid, dysentery |
Touching contaminated surfaces | Athlete's foot, Salmonella (can be transmitted on the feet of flies that land on food that then gets eaten) |
Insect bites | Malaria, dengue fever |