Inhaled secretions, saliva

Box 3.1 Chain of infection

Infectious agent: a microorganism that can cause disease

Reservoir: a place where microorganisms can thrive and

reproduce (e.g. in humans, animals, inanimate objects)

Portal of exit: a means for a microorganism to leave the reservoir

(e.g. respiratory, genitourinary and gastrointestinal tracts; skin

and mucous membranes; and the placenta)

Mode of transmission: how the microorganism moves from one

place to another (e.g. contact, droplets, airborne)

Portal of entry: an opening allowing the microorganism to

invade a new host

Susceptible host: a person susceptible to the disease, lacking

immunity or physical resistance to prevent infection

Source: Adapted from Korn & Lux (2001)

Chain of infection

Infectious

agent

Reservoir

Portal

of exit

Mode of

tranmission

Portal

of entry

Susceptible

host

27

Risks associated with health-care waste

Examples of infections that might be caused by exposure to health-care waste are listed in Table 3.1, together with

the body fluids that are the usual vehicles of transmission and that contaminate waste items. Concentrated cultures

of pathogens and contaminated sharps (particularly hypodermic needles) are the waste items that pose the most

acute potential hazards to health.

Table 3.1

P

otential infections caused by exposure to health-care wastes, causative organisms and

transmission vehicles

Type of infection

Examples of causative

organisms

Transmission vehicles

Gastroenteric infections

Enterobacteria, e.g.

Salmonella

,

Shigella

spp.,

Vibrio cholerae

,

Clostridium difficile

, helminths

Faeces and/or vomit

Respiratory infections

Mycobacterium tuberculosis

,

measles virus,

Streptococcus

pneumoniae

, severe acute

respiratory syndrome (SARS)

 

Ocular infection

Herpesvirus

Eye secretions

Genital infections

Neisseria gonorrhoeae

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