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Rat and Pneumonic models for Third Pandemic Lice models for Second Pandemic Sample sites References 1. WHO (1999). Plague manual: Epidemiology, Distribuon, Survaillance and Control. Tech. rep. 99.2. 2. Houhamdi, L, et. al. (2006). Experimental Model to Evaluate the Human Body Louse as a Vector of Plague, J Inf Dis 191.11 p. 1589-1596. 3. Piarroux, AD, et. al. (2013). Plague Epidemics and Lice, Democrac Republic of Congo. Emg Inf Dis 19.3, p. 505-6. 4. Huſthammer, AK, and Walløe, L (2013). Rats could not have been intermediate hosts for Yersinia pess during medi- eval plague epidemics in Northern Europe. J Ach Sci 40, p. 1752-1759. 5. Tran, TNN, et. al. (2011). Brief communicaon: Co-detecon of Bartonella quintana and Yersinia pess in a 11th-15th century burial site in Bondy, France. Am J Phys Anth 145.3, p. 489-494. Pneumonic model Lice model Rat model DIC R0 Beta DIC R0 Beta DIC R0 Beta Givry 1348 638 1.1 0.44 578 1.9 0.066 621 1.3 0.069 Florence 1400 3773 1.0 0.42 1775 1.8 0.063 7944 1.4 0.080 London 1563 4527 1.0 0.42 1483 1.6 0.061 3515 1.2 0.059 Eyam 1666 433 1.0 0.41 436 1.4 0.057 466 1.1 0.048 Stockholm 1710 2038 1.0 0.42 599 1.7 0.062 874 1.1 0.050 Moscow 1771 5967 1.0 0.43 3153 1.8 0.063 >10000 1.3 0.068 Sydney 1900 143 1.2 0.49 90 1.6 0.061 96 1.1 0.053 Hong Kong 1903 698 1.0 0.42 354 1.7 0.062 313 1.1 0.055 Harbin 1910 527 1.2 0.48 552 2.8 0.079 1263 1.8 0.136 Human ectoparasites spread plague during the Black Death and Second Pandemic Katharine R. Dean 1 , Nils Chr. Stenseth 1 , Lars Walløe 2 , Ole Chrisan Lingærde 3 , Barbara Braman 1 , and Boris V. Schmid 1 Introducon Plague, caused by Yersinia pess, can spread through human populaons by mulple transmission pathways. Modern plague transmission is well-doc- umented for the Third Pandemic (beginning in the mid-19th CE), and the most commonly reported routes of infecon in humans are by fleas during a rodent epizooc, or directly between humans by infecous droplets from a pneumonic infecon. 1 However, there is controversy over how plague spread during the Black Death (1346-1353), and throughout the Second Pandemic (13th-19th CE), due to the relavely high mortality and rapid ge- ographic spread in Europe as compared to India. Methods We made three suscepble-infected-recovered (SIR) models to test each of the proposed transmission mechanisms for plague in Europe: primary pneumonic plague, bubonic plague with a human ectoparasite vector, and bubonic plague with rats and fleas. We used mortality data from historical records to compare three epidem- ics of known pneumonic or rat transmission from the Third Pandemic to six European epidemics (shown in the map) from the Second Pandemic with unknown transmission. We fied the determinisc models in a Bayesian framework to the observed data by esmang the transmission parame- ters, and the inial number of suscepble and infected hosts, using MCMC in PyMC2. We assigned a best fing model for each epidemic using the de- viance informaon criterion (DIC) and we esmated R0 using the next-gen- eraon matrix method. Results The results show that a model of human ectoparasite transmission with body lice (Pediculus humanus humanus) fits epidemics during the Black Death and Second Pandemic over rat-borne and pneumonic transmission routes. Conclusions Indirect evidence for the role of body lice in the transmission of plague has come from a variety of sources: experimental studies, co-detecon of plague and a louse-borne disease in a skeleton from medieval France, the collecon of plague infected lice during epidemics, and a lack of archeolog- ical evidence for rats in Northern Europe during the Second Pandemic. 2,3,4,5 Our results support the hypothesis of an alternate mode of plague trans- mission by a human ectoparasite vector in Europe during the Second Pan- demic. Our comparave modeling approach, using Bayesian inference, al- lowed us to ulize limited mortality data to compare modern and historical epidemics. This work supports the growing body of evidence that plague was not spread primarily by rats in Europe, and therefore has epidemiolog- ical characteriscs different from modern plague epidemics. Author Affiliaons 1. Centre for Ecological and Evoluonary Synthesis, Department of Biosciences, University of Oslo, Norway 2. Department of Physiology, Instute of Basic Medical Sciences, University of Oslo, Norway 3. Department of Computer Science, University of Oslo, Norway *We would like to thank Jukka Corander for his contribuon to the methods Date Pop Size Data points Data type Notes Givry , France Jul 1348 – Nov 1348 1 500 138 Daily Black Death/Second Pandemic Florence, Italy May 1400 – Nov 1400 60 000 180 Daily Second Pandemic London, England Jun 1563 – Jan 1564 80 000 33 Weekly Second Pandemic Eyam, England Jun 1666 – Nov 1666 350 143 Daily Second Pandemic Stockholm, Sweden Aug 1710 – Feb 1711 55 000 24 Weekly Second Pandemic Moscow , Russia Jul 1771 – Dec 1771 300 000 160 Daily Second Pandemic Sydney, Australia Feb 1900 – Aug 1900 400 000 26 Weekly Third Pandemic; Rat transmission Hong Kong, China Jan 1903 – Dec 1903 250 000 50 Weekly Third Pandemic; Rat transmission Harbin, China Dec 1910 – Feb 1911 25 000 68 Daily Third Pandemic; Pneumonic transmission ERCEA Funded MEDPLAG: 324249 Untitled-1.indd 1 31.10.2016 15:39:47
