Pathogens, bacteria, Viruses and Communicable diseases

In this chapter you will learn:

  1. What are Pathogens?

  2. What are bacteria?

  3. What are Viruses?

  4. What are fungi and protists?

  5. What are Communicable diseases?

  6. How to prevent, or reduce the spread of communicable diseases?

What are Pathogens?

A pathogen is a microorganism that causes a disease. Pathogens are highly adopted and they pass very easily from one organism to another.

Pathogens generally enter through mouth, nose, eyes or open wounds.

They can be passed from person to person through the air by speaking, coughing, sneezing or by touching.

Diseases caused by pathogens are highly infectious. These diseases are also called communicable diseases.

There are four main types of pathogens; bacteria, viruses,fungi and protists.

What are bacteria?

Bacteria are small living organism. They Make you ill by damaging cells.

They reproduce rapidly in your body. They can spread from surface to surface.

They can be found everywhere such as air, water, and soil. They generally enter through mouth, nose, eyes or open wounds. They are smaller than plant and animal cells.

They are used to make cheese, medicines and treat sewage.

What are Viruses?

Viruses are made of a short length of genetic material DNA that is surrounded by an outer protein coating.

Viruses are much smaller than bacteria and damage the cells.

Viruses rapidly replicate by invading a cell and using the cell's genetic machinery to reproduce themselves.

Viruses can often survive outside a host for long periods of time.


Fungi can either be single celled or have a body made of hyphae.


Protists are a group of microorganisms that have features that belong to animals, plants and fungi. They use humans and animals as their hosts. The pathogens that cause malaria are protists.

Communicable diseases

Communicable diseases are those that spread by an infectious agent, such as bacteria, viruses, fungi and parasites.

Communicable diseases are also known as infectious or transmissible diseases.

Dirty water also can transmit many types of diarrheal diseases, including cholera.

Unhygienic food preparation can cause bacterial diseases like Escherichia coli.

Salmonella is a type of bacteria that causes food poisoning.

Antibiotics help to cure bacterial disease by killing infectious bacteria inside the body. Examples of antibiotics include penicillin and amoxicillin.

Stomach ulcers

Stomach ulcers can be caused by Helicobacter pylori (H. pylori), a type of bacteria.

Treatments for stomach ulcers include the use of antibiotics and drugs to kill the infection.


Measles is a very infectious viral disease that is often spread by droplets when an infected person sneezes or coughs.

The primary symptoms of measles are a red skin rash and fever.

Most people are adequately protected if they are vaccinated in young age.


Malaria is spread through mosquitos and there is no vaccination for malaria.

These are generally found in areas with higher temperatures like Africa and Asia.

The symptoms of malaria include a fever, vomiting, sweats and chills.

You can reduce the spread of malaria by stopping the mosquitoes from breeding.


Gonorrhoea is a sexually transmitted diseasea and it is caused by the gonorrhoeae bacteria.

The symptoms of a person infected with gonorrhoea bacteria will experience pain when urinating.

Gonorrhoea is treated by antibiotic penicillin.

Athlete's foot

Athlete's foot is a rash caused by a fungus that is usually found between people's toes, which makes skin itch and flake off.

It is most commonly transmitted by touching infected skin or surfaces e.g. swimming pool, changing rooms or gyms.

It can be treated by antifungal medication.

Rose black spot

Rose black spot is a fungus that affects rose plants.

It infects leaves and causes black or purple spots on the leaves.

It can reduce the plant's ability to photosynthesise and growth.

It can be treated by using fungicides.

How to prevent, or reduce the spread of communicable diseases

You should be as hygienic as possible to reduce the spread of communicable diseases.

Early detection and treatment can reduces the chances of spreading a disease.

Diseases can be reduced by washing surfaces with disinfectants and washing your hands before preparing and handling food.

Vaccination can be used to control the spread of communicable diseases.