HLTB21H3 Lecture Notes - Escherichia Coli, Rodent

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Published on 31 Oct 2010
School
UTSC
Department
Health Studies
Course
HLTB21H3
DEFINITIONS
Parasites
– organism that grows, feeds, and is sheltered on or in a different organism and that does not
contribute to the survival of its host
Virus
– ultimate micro-parasite – smaller than bacteria; neither cells not organisms; can only
reproduce within their host
Macroparasites – composed of many cells; does not multiply in host, instead cycles through
transmission stages–eggs and larvae–which pass into the external environment
Transmission
- movement of a parasite from host to host
Incubation period
the interval of time required for development of a disease
Latent period
- seemingly inactive period between exposure to an infection and subsequent illness
Parasite virulence
- capacity of a parasite to cause disease
Zoonotic infections
- animal infections that can be transmitted to humans
MODES OF DISEASE TRANSMISSION
- Direct – occurs through direct contact, e.g. from person to person
- Indirect – through a common route / vector, e.g. contaminated air / water, mosquito
Portal of entry:
Dermal – through the skin, e.g. fungi
Ingestion – through the mouth, e.g. E.coli in water
Inhalation – during respiration, e.g. particulate matter
TYPES OF DISEASE OUTBREAKS
Three main types –
Endemic – usual occurrence of a given disease within a given geographical area
Epidemic – occurrence of a disease in excess of normal expectancy in a defined region
Pandemic – worldwide epidemic
DEFINITION OF PLAGUES
In the past, all disease outbreaks were referred to as plagues
Derived from Latin word ‘plaga’ which means ‘to strike a blow that wounds’.
Today, we refer to such a disease outbreak as an epidemic, comes from Greek word
‘epi’ (“among”) and demos (“the people”).
Acceptable definition of plague: highly infectious, usually fatal epidemic disease.
Plague is a serious, potentially life-threatening infectious disease that is usually transmitted to
humans by the bites of rodent fleas
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Document Summary

Organism that grows, feeds, and is sheltered on or in a different organism and that does not contribute to the survival of its host. Ultimate micro-parasite smaller than bacteria; neither cells not organisms; can only reproduce within their host. Macroparasites composed of many cells; does not multiply in host, instead cycles through transmission stages eggs and larvae which pass into the external environment. Movement of a parasite from host to host. Incubation period the interval of time required for development of a disease. Seemingly inactive period between exposure to an infection and subsequent illness. Capacity of a parasite to cause disease. Animal infections that can be transmitted to humans. Direct occurs through direct contact, e. g. from person to person. Indirect through a common route / vector, e. g. contaminated air / water, mosquito. Ingestion through the mouth, e. g. e. coli in water. Endemic usual occurrence of a given disease within a given geographical area.