How do microorganisms cause diseases?

Many infections and diseases are caused by microorganisms—organisms that cannot be seen without the aid of a microscope. But, not all microorganisms cause disease. There are many bacteria in the environment that don't make you sick. read more

To understand how microorganisms cause disease, you should be able to: Compare and contrast the states of infection and disease. Identify ways to avoid infection by pathogens that use direct and indirect transmission methods. read more

For bacteria and viruses to cause disease they must first colonise the patient. Once they have invaded the host they can multiply readily. If the host is immune to the virus or bacteria due to previous exposure or vaccination, these organisms may not be able to cause disease. read more

The organisms start to multiply within the host causing tissue damage (Disease) by several mechanisms e.g. adherence factors , Invasion factors and toxin production . Opportunistic microorganisms are potentially pathogenic that don’t cause disease under normal conditions but can cause disease in immunocompromised patients , or when they find their way to another site other than their normal habitat . read more