Infection

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Infection
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What is infection

• Infection - the process by which micro-organisms
  enter a susceptible site in the body and
  multiply, which may or may not result in disease
• Colonisation presence of infectious
  micro-organisms in or on the body without any
  disease

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Sources of infection

• People their blood, body fluids, skin,
  secretions and excretions
• Animals their blood, body fluids, skin,
  secretions and excretions
• Food
• Water
• Vectors
• Environment eg soil

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Transmission

• Airborne
• Infectious aerosol - droplets of liquid suspended
  in the air
• gt0.1mm will settle out quickly but smaller
  particle sizes can remain suspended for long
  periods of time
• Size of particle influences deposition in
  respiratory system

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Examples

• Tuberculosis
• Legionellosis
• Flu
• Chlamydiosis (ornithosis/psittacosis)

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Ingestion

• Direct/indirect contact with infectious material
  hand to mouth/eye/nose contact

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Examples

• Enteric infections caused by
• Salmonella
• Shigella
• E. coli O157

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Percutaneous exposure

• Via sharps injury
• Via a vector

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Examples

• Blood-borne viruses eg Hepatitis B C, HIV
• Vector borne disease eg Lyme disease. Malaria,
  West Nile

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Contamination

• Splashes or direct contact (via hands etc
• Eyes
• Mucous membranes
• Broken skin

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Examples

• Leptospirosis
• Tetanus
• Orf
• Ringworm
• Blood-borne viruses

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Other non-occupational transmission routes

• Food/water
• Cholera
• Typhoid
• O157
• Salmonella
• Campylobacter

• STDs
• HIV
• HBV/HCV
• Gonorrhoea
• Syphilis

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Summary - infection

• Sources of infection likely to be associated with
  a particular micro-organism(s)
• Most micro-organisms have a preferred route of
  entry but some can cause infection by other routes