highlights humans' role in spread of disease
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[June 20, 2014]
By Kate Kelland
LONDON (Reuters) - The
discovery of a schistosomiasis parasite egg in a
6,200-year-old grave in Syria may be the earliest
evidence that agricultural irrigation systems in the
Middle East contributed to a vast spread of disease,
scientists said on Friday.
Schistosomiasis - also known as bilharzia, snail fever, or Katayama
fever - is caused by flatworm parasites that live in the blood
vessels of the bladder and intestines. The infection can lead to
anaemia, kidney failure and bladder cancer.
In a study in the Lancet Infectious Diseases journal, researchers
said it may have been spread by the introduction of crop irrigation
in ancient Mesopotamia, the region along the Tigris-Euphrates river
system that covers parts of what is Iraq, Iran, Kuwait, Syria and
The infection, in which the parasite burrows through the skin of
people wading or swimming in waters where it hides in freshwater
snails, has become progressively more common over time and now
causes a huge burden of disease across the world.
According to the World Health Organization, schistosomiasis affects
almost 240 million people worldwide, and more than 700 million
people live in endemic areas.
The egg was found in the pelvic area of the burial grave, where the
intestines and bladder of the person would have been.
The discovery, at Tell Zeidan in northern Syria, was made by a team
of archaeologists and biological anthropologists working at
Cambridge, The Cyprus Institute in Cyprus and the University of
Chicago's Oriental Institute in the United States.
The researchers took soil samples from the head and foot areas of
the grave to act as control samples and found they contained no
parasitic eggs. This suggests the grave site was not contaminated
with the parasite more recently, they said.
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Piers Mitchell of Britain's University of Cambridge, who led the
research team, said the egg may be among the oldest evidence of
man-made technology inadvertently causing disease outbreak.
"The individual who contracted the parasite might have done so
through the use of irrigation systems that were starting to be
introduced in Mesopotamia around 7,500 years ago," he said in a
statement about his findings.
The oldest schistosomiasis egg found previously was in
5,200-year-old Egyptian mummies.
The parasite spends part of its life cycle in snails that live in
warm fresh water, before leaving the snail to burrow through the
skin of people in the water.
(Editing by Louise Ireland)
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