Infectious Diseases

Here are some common ways infectious diseases spread. Be aware so you know how to avoid disease transmission.

What are some causes of Infectious Diseases?

Infectious diseases can be caused by organisms such as viruses, bacteria fungi or parasites. Infectious diseases may be passed via direct contact from person to person, from animal to person or from a mother to the unborn child. They may also be passed by indirect contact such as touching an object like a doorknob that has germs on it. Diseases can also be spread via insects or contaminated food.

Common ways infections are spread

Direct Contact

Person-to-person contact 

This happens when germs spread through direct transfer from one individual to another. This can happen if someone touches, kisses, coughs or sneezes on another person and spreads the bacteria or virus directly to others. Body fluids such as blood or mucus can also spread diseases during sexual contact.

There are ways you can prevent various organisms spreading from person to person such as: 
    • Frequently washing hands with soap and water for 20 seconds 
    • Staying up to date on all recommended vaccinations 
    • Wearing a mask if you will be in a crowded area or if you feel unwell 
    • Practising safe sex. Abstain from casual sex with different partners and always use a condom. Test yourself and your partner for sexually transmitted infections including HIV before changing partners

Mother to unborn child 

A pregnant woman can pass infectious diseases to her baby via the placenta during pregnancy, from germs in the vagina during birth, or from breast milk after birth. Different organisms may spread via different routes, so it is recommended for pregnant women to follow the advice of their doctor to get all necessary screening during pregnancy to detect diseases and take actions that can prevent the baby from acquiring the infection.

Animal to person 
Scratches or bites from an infected animal or handling animal waste can make you ill. Avoid contact with the saliva of a wild or an animal unfamiliar to you.

You can prevent being infected by an animal by: 
    • Avoiding the licks, scratches or bites of an animal 
    • Getting a rabies vaccination if you will potentially be around wild/infected animals or after receiving a bite or scratch from an unknown animal 
    • Washing any bites/scratches with soap and water well; see a doctor for wound care and advice on medication or vaccination that may be needed 
    • Using gloves and a mask when handling animal waste and washing hands with soap and water for 20 seconds after contact with the animal or animal waste

Indirect Contact

Contaminated Objects or Surfaces

Diseases can be passed from one person to another by indirect contact. For example, any object has the potential to be a carrier of an infectious agent. Dirty clothes and linen, common surfaces such as doorknobs, utensils and unsterilised hospital equipment are some examples of breeding grounds for bacteria and viruses that can live on surfaces for different lengths of time depending on the nature of the germ and environmental conditions. This can happen when an infected person coughs or sneezes and the disease-causing organisms land on the object.

Food contamination 

Diseases can spread through food and water that is contaminated, including undercooked meat or eggs or unpasteurized milk products or juices. 

Prevent foodborne illnesses by: 
    • Cooking all meat and eggs well 
    • Washing all fruits and vegetables in clean water 
    • Only drinking water from sources that have been treated through filtration, boiling, or bottled 
    • Keep food preparation surfaces clean and cook food at the proper temperatures 
    • Promptly refrigerate food that is left over as soon as it has cooled. Don’t leave cooked foods at room temperature for long periods of time


Some diseases move from person to person (their “host”) via an insect that carries the disease (their “carrier” or “vector”). Common vectors are mosquitoes, fleas, lice, or ticks.

  • You can prevent being infected by diseases carried by insects by: 
    • Avoiding mosquito bites with the use of repellants, bed nets and clothing that covers the skin when in areas with mosquitoes
    • keeping living areas clean and free of rodents
    • Wear long clothing to cover skin if going into areas with high vegetation to avoid tick bites 

Some germs can spread via multiple routes. For example, the common cold virus may spread via person-to-person transmission if someone coughs or sneezes next to you and the virus is inhaled directly. it may also spread via indirect contact if the virus lands on a doorknob or table and later another person touches that surface and gets the virus into their mouth, nose, or eyes by touching their face. Click here for more information on specific infectious diseases and how you can prevent them. 

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