MELS223 Lecture 4 7/18/2013 4:04:00 PM
Avian influenza: H5N1 – low infectivity, high mortality
Swine flu: H1N1
To study the natural history of four infectious diseases.
Define terms acute, chronic, asymptomatic, latent
To distinguish between different bacterial “strategies” which
lead to evolutionary success.
To discuss the importance of carriage of pathogens.
Brock “Biology of Microorganisms” 13th ed. Carriers p.946–
947; Influenza p. 986; Tuberculosis 979–980. The science of
epidemiology p. 942 (12th ed.” Carriers p821-822; Influenza
p862–864; tuberculosis p854–856; epidemiology pp. 942–
Further Reading on Cryptosporidium at:
Encountering a pathogenic microorganism
1. Period of multiplication
Eliminated Transmitted to new host
End point = want to colonise and invade, replicate in
Host provides: nutrients, water, temperature, osmolarity, pH
To microbe, production of disease..
Helpful – diarrhoea. Spreads to new host
Unhelpful – kills host!
(sometimes, accidental side effect like tetanus)
Remain in host long term, disease (chronic). Lots of
opportunity to transmit to a new host Remain in host short term, but high infectivity (acute)
Remain in host, no symptoms of disease ( asymptomatic,
Part of normal microflora
Humans not main reservoir (eg. Environ