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Black Death spread by humans, vindicating rats

One of the worst pandemics in human history, the Black Death, along with a string of plague outbreaks that occurred d...

Posted: Jan 16, 2018 12:21 PM
Updated: Jan 16, 2018 12:21 PM

One of the worst pandemics in human history, the Black Death, along with a string of plague outbreaks that occurred during the 14th to 19th centuries, was spread by human fleas and body lice, a new study suggests.

It was previously suggested that rodents, whose fleas can also transmit the bacteria behind the plague, were the main culprits behind Europe's second pandemic of the disease that saw a string of outbreaks occur in succession.

Plague is caused by infection with the bacterium Yersinia pestis

More than 1,800 people were infected with the plague last year

Plague is caused by infection with the bacterium Yersinia pestis and is typically spread through the bite of infected fleas, frequently carried by rats, causing bubonic plague. Symptoms include painful, swollen lymph nodes, called bubos, as well as fever, chills and coughing.

Pneumonic plague is more virulent or damaging and is an advanced form characterized by a severe lung infection. The infection can be transmitted from person to person via airborne droplets -- coughing or sneezing. Outbreaks still occur today, with an outbreak in Madagascar last year infecting more than 1,800 people.

To understand the historic outbreak, scientists from the University of Oslo modeled the three transmission routes for the disease -- rats, airborne and human fleas and lice -- using mortality data for nine outbreaks that spanned the time period of the second pandemic. Their analysis found that human ectoparasites, such as fleas, reflected the death trends most accurately.

The model outcomes therefore suggest the spread of the plague back then was mainly attributable to human fleas and body lice, according to the study published Monday.

"Our results support that human ectoparasites were primary vectors for plague during the Second Pandemic, including the Black Death," the authors write.

This challenges "the assumption that plague in Europe was predominantly spread by rats," they added.

"This study uses mathematical modeling to try and determine how exactly the plague spread in Europe during the pandemic known as the 'Black Death'," said Raina MacIntyre, professor of Infectious Diseases Epidemiology at the University of New South Wales in Australia, who was not involved in the study.

"Most naturally occurring plague is bubonic (affecting the lymph nodes, rather than the lung). Studies like this can help better understand rapid transmission of plague, which then points to the most suitable control measures."

Minnesota Coronavirus Cases

Data is updated nightly.

Cases: 454989

Reported Deaths: 6163
CountyCasesDeaths
Hennepin943781502
Ramsey40624748
Dakota33540354
Anoka31357368
Washington20533237
Stearns18091190
St. Louis13970250
Scott1217799
Wright11791107
Olmsted1078075
Sherburne829669
Carver704439
Clay658884
Rice624274
Kandiyohi558072
Blue Earth548033
Crow Wing490478
Otter Tail464268
Chisago459538
Benton423688
Winona394548
Douglas379366
Nobles374647
Mower373729
Goodhue356863
Polk330760
McLeod328147
Beltrami315748
Morrison314545
Lyon305539
Becker288939
Itasca287343
Isanti285643
Carlton284043
Steele278910
Pine270315
Freeborn254123
Todd233730
Nicollet229438
Brown218034
Mille Lacs215645
Le Sueur214216
Cass210724
Meeker201333
Waseca193216
Wabasha17463
Martin171926
Roseau166417
Hubbard150738
Redwood141127
Houston140014
Dodge13934
Renville138440
Chippewa133032
Cottonwood129018
Fillmore12698
Wadena120818
Rock112012
Aitkin111433
Sibley10997
Faribault109416
Watonwan10688
Pennington101016
Kanabec99618
Pipestone96823
Yellow Medicine94916
Murray9117
Jackson87310
Swift84518
Pope7475
Stevens7078
Marshall70315
Clearwater68814
Lake66315
Lac qui Parle66116
Wilkin6339
Koochiching60610
Lincoln4912
Unassigned47369
Big Stone4693
Grant4388
Norman4258
Mahnomen4167
Kittson37420
Red Lake3204
Traverse2613
Lake of the Woods1961
Cook1160

Iowa Coronavirus Cases

Data is updated nightly.

Cases: 311430

Reported Deaths: 4433
CountyCasesDeaths
Polk46841465
Linn18065279
Scott15872172
Black Hawk14090243
Woodbury13129181
Johnson1230052
Dubuque11625159
Pottawattamie9166115
Dallas908972
Story881038
Cerro Gordo473572
Webster472477
Sioux459757
Warren459339
Clinton458168
Marshall431162
Buena Vista396330
Muscatine396178
Des Moines395143
Plymouth353270
Wapello350798
Jasper332859
Lee324632
Marion309353
Jones274950
Henry267131
Carroll258434
Bremer250148
Crawford234724
Boone222917
Washington222933
Benton213650
Mahaska197937
Jackson195032
Tama190259
Dickinson188829
Kossuth180644
Delaware176236
Clay172521
Wright167124
Fayette166024
Hamilton162330
Buchanan162224
Winneshiek160820
Harrison158562
Hardin157931
Cedar155619
Clayton153849
Butler151724
Page147115
Floyd141636
Cherokee140127
Mills138517
Lyon137533
Poweshiek135224
Hancock131924
Allamakee130930
Iowa127722
Madison123910
Calhoun12349
Grundy122628
Winnebago122229
Jefferson122125
Mitchell116837
Louisa116230
Cass115243
Chickasaw113712
Appanoose112640
Sac112215
Union111623
Emmet111332
Humboldt106819
Shelby105527
Guthrie104424
Franklin103618
Unassigned10160
Palo Alto92411
Montgomery89124
Keokuk86326
Howard85919
Monroe82220
Clarke8129
Pocahontas78211
Ida76030
Davis70321
Greene6977
Adair69620
Monona68518
Lucas66710
Osceola64711
Worth6194
Taylor5999
Fremont5246
Van Buren50215
Decatur4974
Ringgold45111
Audubon4228
Wayne42021
Adams3003
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