Infection and Response

Pathogens - 

A pathogen is a microorganism that causes a disease. There are 4 types of pathogens: 

• Viruses 
• Bacteria 
• Fungi
• Protists 

They infect a host, reproduce themselves or replicate if it is a virus, spread from thier host and infect other organisms. 

Diseases caused by pathogens are called communicale diseases (they can be tranfered from one person to another)

Transmission - 

• Direct contact - this can be sexual contact during intercourse or non-sexual contact, like shaking hands 
• Water - Dirty water can transmit many diseases, such as the cholera bacterium 
• Air - When a person who is infected by the common cold sneezes, they can spray thousands of tiny droplets containing the virus particles to infect others 
• Unhygenic food preperation - Undercooked or reheated food can cause bacterial diseases like food poisioning 
• Vector - Any organism that can spread a disease is called a vector.

Symptoms - 

• Fever 
• Skin rash 
• Dry cough 
• Runny nose
• Inflamed eyes (conjuntivitis) 
• Infertaltiy (in extreme cases) 

Many children in develpoed countires are given vaccines agaisnt measles. 

Symptoms - 

• Fever 
• Skin rash 
• Dry cough 
• Runny nose
• Inflamed eyes (conjuntivitis) 
• Infertaltiy (in extreme cases) 

Many children in develpoed countires are given vaccines agaisnt measles.