Public release date: 18-Mar-2008
Contact: Mary Kohut
Press@[EMAIL PROTECTED]
Library of Science
Mekong schistosomiasis is more widespread than previously thought
A new genetic analysis, published March 19th in the open-access
journal PLoS Neglected Tropical Diseases, suggests that the parasitic
worm Schistosoma mekongi is more widespread than previously thought.
According to the study, the human population at risk of infection
could be up to 10 times greater than previously estimated.
Furthermore, it posits an increased possibility of the spread of the
parasite across Laos and Vietnam.
Schistosomiasis, a parasitic disease which affects over 200 million
people worldwide, is caused by several flatworm species of the genus
Schistosoma. In the Mekong River basin in South-East Asia, the disease
is transmitted by the species Schistosoma mekongi. A mass treatment
program in the mid-1990s greatly reduced the prevalence of the disease
and encouraged optimism regarding the control of S. mekongi infection.
However, based on the implications of this new study, the control of
Mekong schistosomiasis could be problematic.
Researchers Stephen W. Attwood of China's Sichuan University, Farrah
A. Fatih of London's Natural History Museum, and E. Suchart Upatham of
Thailand's Mahidol University analyzed DNA sequences of sample
organisms collected from the Mekong river and its tributaries in
Cambodia, Laos and Malaysia. They found, contrary to the previously
held belief that S. mekongi is confined to a small section of the
lower Mekong River, that organisms collected in its tributaries across
Cambodia were also of the species S. mekongi. The range of the snail
intermediate host and the ecological conditions for potential
transmission were also shown to be much broader than once thought.
Prior to this study it was also assumed that S. mekongi originated in
Yunnan, China, migrated southwards across Laos and into Cambodia, and
later became extinct in Laos due to conditions unsuitable for
transmission. However, Attwood and colleagues' analysis suggested a
more recent, and ongoing, migration northwards from Vietnam, towards
Cambodia and Laos.
According to the authors, further work is required into this problem,
as, if we have no reason to assume that ecological conditions in Laos
are unsuitable for transmission, we may expect the future spread of
this disease northwards into Laos.
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PLEASE ADD THIS LINK TO THE PUBLISHED ARTICLE IN ONLINE VERSIONS OF
YOUR RE****T: http://www.plosntds.org/doi/pntd.0000200
(link will go
live on Wednesday, March 19)
CITATION: Attwood SW, Fatih FA, Upatham ES (2008) DNA-Sequence
Variation Among Schistosoma mekongi Populations and Related Taxa;
Phylogeography and the Current Distribution of Asian Schistosomiasis.
PLoS Negl Trop Dis 2(3): e200. doi:10.1371/journal.pntd.0000200
CONTACT:
Stephen W. Attwood
Sichuan University
State Key Laboratory of Biotherapy
Gaopeng Street
Keyuan 4 Lu
Chengdu, Sichuan 610041
China
+86 28 8516 4098
swahuaxi@[EMAIL PROTECTED]
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