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Ways infectious diseases spread

Infectious diseases can spread in a variety of ways:

Some infections can be spread in several ways.

Airborne droplets from the nose and throat

Some infections are spread when an infected person sneezes or coughs out tiny airborne droplets. The droplets in the air may be breathed in directly by another person or indirectly enter another person through contact with surfaces and hands with the droplets on them.

Examples of airborne diseases:

Urine

Some infections are spread when urine from an infected person is transferred from soiled hands or objects to the mouth.

Example of a disease spread by urine:

Faecal-oral

Some infections are spread when microscopic amounts of faeces from an infected person with symptoms or an infected person without symptoms (a carrier) are taken in by another person by mouth. The faeces may be passed:

  • directly from soiled hands to the mouth
  • indirectly by way of objects, surfaces, food or water soiled with faeces.

Examples of diseases spread from faeces:

Blood or body fluids

Some infections are spread when blood or other body fluids from an infected person comes into contact with the mucous membranes (the thin moist lining of many parts of the body such as the nose, mouth, throat and genitals) or bloodstream of an uninfected person, such as through a needle stick or a break in the skin.

Examples of diseases spread through blood/body secretions:

Skin or mucous membrane contact

Some infections are spread directly when skin or mucous membrane (the thin moist lining of many parts of the body such as the nose, mouth, throat and genitals) comes into contact with other skin or mucous membrane. Infections are spread indirectly when skin or mucous membrane comes in contact with contaminated objects or surfaces.

Examples of diseases spread by skin or mucous membrane contact:

Sexually transmitted infections

These infections are most commonly transmitted by sexual contact. Sexual contact means:

  • genital to genital
  • oral to genital
  • oral
  • genital to anal.

Examples of sexually transmitted infections:

Food or waterborne diseases

These diseases result from ingestion of water or a wide variety of foods contaminated with disease-causing microorganisms or their toxins. Often these infections are also spread by the faecal-oral route.

Examples of food or waterborne diseases:

Saliva

Some infections are spread by direct contact with saliva (such as kissing) or indirect contact with contaminated objects (such as children sucking and sharing toys).

Examples of diseases spread by saliva:

Diseases where person-to-person spread occurs rarely, if ever

Some infectious diseases are almost never spread by direct contact with an infected person. These diseases are usually spread by contact with an environmental source such as animals, insects, water or soil.

Examples of diseases spread by contact with animals:

Examples of diseases spread by insects and in the examples listed below, specifically by mosquitoes:

Examples of diseases spread by contact with water or soil:

 

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