Module 7 – Infectious Disease Notes

Resource Description

Module 7 – Infectious Disease Notes by C.M

Working Scientifically

Reliability, Accuracy, Validity

Reliability
⦁ First-hand investigations: XPT must be repeated and show consistent results
⦁ Secondary sources: Must be unbiased, appropriately recorded, current, reputable

Accuracy
⦁ Primary: XPT design is valid, results are close to true value of quantity being measured
⦁ Secondary: Information consistent across multiple reliable sources

Validity
⦁ Primary: Investigates what you intended to, controls variables, uses suitable equipment
⦁ Secondary: Info gathered with appropriate methods, relates to research topic

Dependent, Independent, Controlled variables

Dependent: Variable that is being measured, changes in response to independent. (e.g. temperature of water changes in response to time heated)

Independent: Controlled by experimenter to cause phenomena.

Controlled: Kept the same across all samples/subjects to make sure dependent variable is actually changing in response to independent variable.

Risk Assessment
⦁ Hazard
⦁ Risk
⦁ Mitigation

Causes of Infectious Disease – How are diseases transmitted?

Infectious diseases and disease transmission

Classifying different pathogens: (disease causing agents)

Microscopic, cellular (living)
⦁ Protozoa: Unicellular eukaryotes, parasites. Usually reproduce through binary fission, motile (moves with flagellum/cilia). Obligate—only continues life cycle in host.
⦁ Fungi: Eukaryotic. Can be unicellular (yeast, e.g. thrush) or multicellular (mould, e.g. tinea). Usually attack body surfaces. Consist of branching filaments called hyphae which form a structure called mycelium. Opportunistic—waits for immune system weakness before becoming pathogenic.
⦁ Bacteria: Unicellular prokaryotes. Can cause disease by competing with good bacteria or through exotoxins (secreted) or endotoxins (released upon death). Genetic material = 1 circular chromosome.

Microscopic, non-cellular (non-living)
⦁ Viruses: Cannot reproduce independently. Have nucleic acid contained in a protein coat/capsid. Can be DNA-based (adenoviruses, e.g. common cold) or RNA-based (retroviruses, e.g. HIV). Invades a host cell, where its nucleic acid is translated into proteins, forming new copies (virions). The cell is filled with these virions and bursts, releasing them. Obligate and intracellular—only reproduces in host.