Spores of fungus, <em>Candida albicans</em> b/w Spores of fungus, <em>Candida albicans</em>

Spores of fungus, Candida albicans

The long strands are the tubular filaments (hyphae) that have developed from the fungal spores. Yeast cells (rounded, yellow) are budding from the ends of the hyphae (red). Candida albicans causes the infection known as candidiasis which affects the moist mucous membranes of the body, such as skin folds, mouth, respiratory tract and vagina. Oral and vaginal conditions are known as thrush.

Microbes and the human body

The surfaces of the human body inside and out, for example the skin, mouth and the intestines, are covered in millions of individual micro-organisms that don’t do us any harm. In fact they help to protect us from becoming infected with harmful microbes. They are known as the normal body flora.

The number of normal bacterial cells that live on the body is in the region of 100 million. This number is 10 times greater than the 10 million cells that make up the human body.

Artwork of a human figure surrounded by disease-causing microbial pathogens

Microbes and disease

Microbes that cause disease are called pathogens. Find out which microbe is responsible for causing malaria!

Computer artwork of the immune system protecting the body against invading pathogens

Immune system

An infection can be seen as a battle between the invading pathogens and host. How does the immune system work?

Illustration of antibody action on invading bacteria


Discover more about the antibody antigen interaction.

Close-up of a running nose

Routes of transmission

Find out how you can pick up germs and pass them on to others.

Close-up of a doctor giving an influenza (flu) vaccination.


Just a shot in the arm - what do vaccines do?

Notes on and a drawing of the original culture plate of the fungus Penicillium notatum


Antibiotics are powerful medicines that only fight bacterial infections.

Giardia lamblia

Did you know that this protozoan causes really bad flatulence!

Bacillus thuringiensis

Discover how this bacterium can be used as a pesticide.