Health care-associated infections

Infections are caused by bacteria, fungi or viruses entering the body through one or more of the following routes.

• person-person via hands of health-care providers patients and visitors;

• personal equipment (e.g. stethoscopes, computers) and clothing;

• environmental contamination;

• airborne transmission;

• carriers on the hospital staff;

• rare common-source outbreaks.

Epidemiological evidence suggests that multidrug-resistant organisms are carried from person-to-person by health-care professionals.

Carriers are individuals who harbor disease organisms in their body without visible symptoms and may pass the infection to another person.   It is possible to carry an organism without being aware of it for example, Typhoid Mary a woman who carried the typhoid bacillus and unknowingly started an epidemic in the US in the 1880s .

Outbreak is a term used in epidemiology to describe an occurrence of disease greater than would otherwise be expected in a particular time and place. It may be small and localized group or impact upon thousands of people across an entire continent. Two linked cases of a rare infectious disease may be sufficient to constitute an outbreak. Outbreaks may also refer to epidemics, which affect a region in a country or a group of countries, or pandemics, which describe global disease outbreaks.

Common source outbreak

Some diseases arise from a single definable source, such as a common water supply.

The basic idea is that common source outbreaks are not propagated from individual-to-individual (e.g., person-to-person). Instead, sick individuals typically are propagation dead ends.

Yet the disease continues to be endemic and perhaps epidemic as a consequence of contact with some typically geographically well-defined disease reservoir.