Disease

DiseaseSource of vulnerability

Important questions to answer

What is a disease?

What is infection?

Is disease the same as infection

What causes disease or infection

How is a disease transmitted?

Is the disease a source of vulnerability?

Disease vs Infection

What is a disease?DISEASE: an abnormal

condition of body function(s) or structure that is considered to be harmful to the affected individual (host)

Emerging Infectious

diseases (EIDs)New diseases and diseases with increasing incidences are called EIDs

Disease vs Infection

What is an infection?INFECTION: the colonization

and/or invasion and multiplication of pathogenic microrganisms in the host with or without the manifestation of disease

What causes people to get ill?MicroorganismsBacteriaViruses

Bacteria vs Viruses

What are bacteria? Bacteria are unicellular

prokaryotic organisms characterized by the lack of a membrane-bound nucleus and membrane-bound organelles.

Can be aerobic or anaerobic Most are one of three typical

shapes (bacillus, cocci, spiral)

Bacteria vs Viruses

What are viruses? Viruses are noncellular structure

composed mainly of nucleic acids (DNA or RNA) contained within a protein coat known as a capsid.

They are considered nonliving because they fail to meet several of the commonly accepted criteria of life

How is a disease transmitted

PATHOGEN ENVIRONMENT

HOST

DISEASE

TRIAD Hos

t-Par

asite

Inte

ract

ions

OTHER MICROBES

Microbial Interactions

Disease Transmission

Communicable vs. Non-communicable

Modes of transmission

Communicable vs. Non-communicable

Non-communicable: cannot be transmitted from an infected person to a susceptible healthy one

CommunicableTransmitted from person to person

Directly: person-to-person contactIndirectly: vehicle, vector, fomite

EPIDEMIOLOGY

EPIDEMIC: disease occuring suddenly in numbers clearly in excess of normal expectancy

ENDEMIC: disease present or usually prevalent in a population or geographic area at all times

PANDEMIC: a widespread epidemic distributed or occuring widely throughout a region, country, continent, or globally