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Note Some information on this page copied from SA Dept of Human Services web site (with permission).

Spread of Infection

Infectious diseases can spread in a variety of ways: through the air, from direct or indirect contact with another person, soiled objects, skin or mucous membrane, saliva, urine, blood and body secretions and through sexual contact.
Airborne droplets from nose and throat
Some infections are spread when an infected person sneezes and coughs out tiny airborne droplets. The droplets in the air may be breathed in directly by another person, or indirectly enter another person though contact with surfaces and hands with the droplets on them.
Examples . . .
  • Chickenpox
  • Common cold
  • Diphtheria
  • Haemophilus influenzae type b (Hib)
  • Influenza
  • Measles
  • Meningitis (bacterial)
  • Meningococcal disease
  • Mumps
  • Parvovirus infection (human parvovirus infection, parvovirus B19 infection, slapped cheek, slapped face, erythema infectiosum, fifth disease)
  • Pneumococcal pneumonia
  • Rubella
  • Streptococcal sore throat
  • Tuberculosis (TB)
  • Whooping cough (pertussis)
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 mouth or indirectly by way of objects, surfaces, food or water soiled with faeces.
Examples . . .
  • Campylobacter infection
  • Cryptosporidiosis
  • Giardiasis
  • Hand, foot and mouth disease
  • Hepatitis A
  • Meningitis (viral)
  • Rotavirus infection
  • Salmonella infection
  • Shigella infection
  • Thrush
  • Viral gastroenteritis
  • Worms
  • Yersiniosis
Skin or mucous membrane (lining of nose and mouth) contact
Some infections are spread directly when skin or mucous membrane comes into contact with other skin or mucous membrane. Infections are spread indirectly when skin or mucous membranes come in contact with contaminated objects or surfaces.
Examples . . .
  • Chicken pox
  • Cold sores (herpes simplex)
  • Conjunctivitis
  • Hand, foot and mouth disease
  • Head lice
  • Molluscum contagiosum
  • Ringworm
  • Scabies
  • School sores (impetigo)
  • Staphylococcus aureus
  • Thrush
  • Warts (common, flat and plantar)
Some infections are spread by direct contact with saliva (such as kissing) or indirect contact with contaminated objects (children sucking and sharing toys).
Examples . . .
  • Cytomegalovirus infection (CMV)
  • Glandular fever (mononucleosis)
  • Hepatitis B
Some infections are spread when urine is transferred from soiled hands or objects to the mouth.
Example . . .
  • Cytomegalovirus infection (CMV)
Blood/body secretions
Some infections are spread when blood or body secretions from an infected person come into contact with the mucous membranes of an uninfected person or the tissues beneath the skin, such as through a needle stick or a break in the skin.
Sexually transmissible diseases
These diseases are most commonly transmitted by sexual contact. Sexual contact means genital to genital, oral to genital or genital to anal contact. Sexually transmissible diseases can also be spread in other ways.
Examples . . . 
  • Bacterial vaginosis
  • Candidiasis
  • Chlamydia
  • Gonorrhoea
  • Hepatitis A
  • Hepatitis B
  • Hepatitis C
  • Herpes
  • Non specific urethritis (NSU)
  • Pubic lice (crabs)
  • Syphilis
  • Trichomoniasis
  • Warts (genital)
Diseases where person-to-person spread occurs rarely, if ever
Some infectious diseases cannot be spread by direct contact with an infected person. These diseases are spread by contact with an environmental source such as animals, insects or contaminated water.
Examples . . .
1. Spread by contact with animals
  • Hydatid disease
  • Psittacosis
  • Q fever
  • Toxoplasmosis
2. Spread by insects
  • Ross River virus
  • Dengue fever
3. Spread by contact with water or soil
  • Amoebic meningo-encephalitis
  • Legionellosis (Legionella pneumophila and Legionella longbeachae)
  • Tetanus

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