Black death

The Black Death arrived in Sicily in 1347 and within two years had swept northwards to Scandinavia, at a time when rats appear to have been absent from much of Europe (Twigg, 1984, 2003). Even if introduced at ports, rat populations could not feasibly have colonized such large areas so quickly. New examination of contemporary accounts, and local parish records, reveal patterns of death that are consistent with a directly transmitted infection among family members and neighbours, with symptoms consistent with some sort of viral haemorrhagia. The real ‘vector’ appears to have been man: occasional introductions to certain nearby towns and villages coincided with the arrival of travellers on foot or horseback (Scott and Duncan, 2004). People at the time were aware of the effectiveness of isolation and quarantine within affected households, which would not have prevented infection spread by rats and fleas. It seems that only the limited transport and movement patterns of the time prevented even greater impacts on the European human population.

http://www.map.ox.ac.uk/PDF/Tatem_etal_2006.pdf

Global Transport Networks and Infectious Disease Spread
A.J. Tatem1, D.J. Rogers1 and S.I. Hay1,2
1TALA Research Group, Tinbergen Building, Department of Zoology,
University of Oxford, South Parks Road, Oxford OX1 3PS, UK
2Malaria Public Health & Epidemiology Group, Centre for Geographic
Medicine, KEMRI, PO Box 43640, 00100 Nairobi GPO, Kenya