PARA 410 Lecture Notes - Lecture 16: Pertussis, Bordetella, Orthohantavirus
12 Jun 2018
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Population Dynamics and Transmission – January 17
Pertussis (Whooping Cough)
• Caused by bacteria, Bordetella pertussis
• Period until infectious about 8 days
• Infectious period of 14-21 days (where symptoms appear)
• Recovery within one to two months
• Death in developed countries rare since mass vaccination started more than 50 years ago
• In many places, whooping cough remains endemic, with epidemic outbreaks every 3-5 years
(inter-epidemic period: how long between epidemics?)
• Name based on characteristic: severe hacking cough followed by intake of breath that sounds like
"whoop"
Spread of Pertussis from Urban Centres in Senegal
• Figure: white parts = starts in cities with concentrated populations
• Vaccination increases the inter-epidemic period
o Common and expected outcome of vaccination
o Increase inter-epidemic period due to less people susceptible from vaccine = slow down
transmission since not many can catch it
o Can also increase severity of the disease if catch it when older and not had it before nor got
vaccinated against it
Factors that Affect Transmission
• Do they DIRECTLY affect transmission or DIRECTLY affect another process?
o Age
▪ Transmission (age-related susceptibility)
▪ Natural death of the resistant > natural death rate of susceptible
▪ Disease-induced death rate
▪ Recovery: older people have weaker immune systems
▪ Birth: older people not likely to reproduce
o Vaccination rate
find more resources at oneclass.com
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Document Summary
In many places, whooping cough remains endemic, with epidemic outbreaks every 3-5 years (inter-epidemic period: how long between epidemics?: name based on characteristic: severe hacking cough followed by intake of breath that sounds like. Spread of pertussis from urban centres in senegal. Figure: white parts = starts in cities with concentrated populations: vaccination increases the inter-epidemic period, common and expected outcome of vaccination. Images: mouse plague: numbers in epidemic (extraordinarily high population) Simple flowchart describing mouse population dynamics: the number of mice increases with birth and immigration and decreases with death and emigration. If the rate of inputs (birth and immigration) exceeds the rate of losses (death and emigration), the mouse population grows: conversely, when the rate of losses exceeds the rate of inputs, the mouse population declines. Processes versus factors: processes, birth - increase population, death - decrease population. Immigration - increase population: emigration - decrease population. Emerging viral and bacterial infections transmitted by rodents.
