Lecture notes Biodiversity: Exploiters and Exploited Flees, Rats and Plague (BI2EEE4)

29.10.19


L5 – Flees, rats and the plague (Yersinia pestis)
1930s Malaria – cure syphilis in large doses
Keywords:
Enzootic disease cycle (when a disease is constantly in a pop but only affects a few animals at a
time), plague, Enterobacteriaceae, epidemic, slycatic disease cycle (part of a disease cycle that
occurs in wild animals), sylvatic (wild animals that can carry diseases ish), epizootic cycle,
pneumonic, commensal rodent (lives around people)

Lecture:
 Basics
o One of two epidemic diseases (other cholera and smallpox excluded in 1981)
o All cases reported to WHO
 History
o Evolved 15-20k years ago from Y. pseudotuberculosis
 2 plasmids acquired
 Pfra = phospholipase D (controls host defense)
 pPst = plasminogen activator (promotes collineation in mammals)
o 19th century China
 Noticed late by Western world
 Possibly started in mid-18th century
 3rd pandemic (in British owned Hong Kong & spread to India ect until 20 th
century – 6 mil deaths )
 2nd pandemic = black death
 Different biovars of Y. pestis caused all 3 pandemics
 Pasters group worked out – bacteria
 60s = most common in Asia and 90/00s = Africa
o Now
 Europe does not have plague anymore (no species of rodent able to be a
carrier)
 1995 = First drug resistant strain in Madagascar
 3 worldwide known diseases IDed by WHO: typhoid, plague and smallpox
 Basic info of Yersinia pestis
o Most animals can get it (resistance can be present so low disease content)
 Enzootic plague cycle = carrier to disease
o No resistance rats (die quickly but amplifying hosts)
 Rattus rattus – black/ship rat
 Rattus novegicus – brown rat
o Plague zoonosis
 Plague = disease of rats that man participates
 Flees = vector
 Pneumonic plague = transmit person to person
 Characteristics of the bacteria
o Non motile, non-spore forming
o Coccobacillus
o Gv -, gut bacteria (Enterobacteriaceae)