Researchers from the
Johns Hopkins Bloomberg School of Public Health have
developed an environmentally friendly and potentially
affordable way to fight schistosomiasis, a disease caused
by parasitic worms in water.
The scientists found that spraying parasite-infested
water surfaces with a combination of a red cedarwood oil
distillate (from Juniperus virginiana trees) and the food
additive Tween 80 rapidly inactivates and kills infective
Schistosoma mansoni larvae. Previous research had shown
that frequent application of topical creams was one way to
control exposure to the parasite, which causes schistosome
disease, but the procedure was difficult to sustain.
Although not found in the United States,
schistosomiasis impacts 200 million people worldwide. It is
the No. 1 cause of bladder cancer in the developing world
and a leading worldwide cause of liver failure due to
cirrhosis (scarring of the liver). The authors' findings
are published in the November issue of the American
Journal of Tropical Medicine and Hygiene.
The study, which was authored by Jean Marie Naples and
Clive J. Shiff, of the
Department of Molecular Microbiology and Immunology,
and Rolf U. Halden, of the
Department of Environmental Health Sciences and Center
for Water and Health, is a new approach to decreasing the
spread of schistosomiasis and may help in the control of
this insidious parasitic disease. Besides red cedarwood,
there are many similar natural oils that can be extracted
from Juniperus trees in all parts of the world that may
also be effective, according to the Hopkins researchers.
It has been shown that bird schistosome parasites were
responsible for recent outbreaks of swimmer's itch at
beaches in Canada and the United States. Bird schistosome
parasites are in the same family as human schistosome
parasites. The red cedarwood oil distillate created by the
Hopkins scientists may also protect against swimmer's
itch.
Cercariae, the infective larvae form of the parasite,
gather at or near the surface of water in order to improve
their chances of finding a vertebrate host. In their
research, the Hopkins scientists combined one part cedar
oil distillate with five parts of Tween 80, which is an
agent that reduces the surface tension of water; the
combination resulted in a surface-active formulation that
will economically treat large bodies of water, regardless
of depth and volume.
The researchers found that applying the mixture to the
water's surface blocked the ability of cercariae to
penetrate skin. When mice were exposed to
schistosome-infested water treated with the formulation,
there was a 99.2 percent reduction in worm burden in these
mice, as compared to mice exposed to untreated
parasite-infested water.
Cedarwood oil is approved as a flavor additive for
food and liquids and as a fragrance agent by the Food and
Drug Administration, and by the Environmental Protection
Agency in soaps, detergents and cosmetics. Tween 80, a food
additive, is biodegradable. The cedar oil distillate also
stands up well to harsh environmental conditions. Samples
exposed in Ghana to direct heat and sunlight for six weeks
remained effective for inactivation of Schistosoma mansoni
larva.
The researchers have planned additional field trials
in still and moving bodies of water to study effects on
human and bird schistosome cercariae.
The School of Public Health is seeking a patent for
the surface-active formulation, which has potential
commercial applications in the United States and other
developed countries for the prevention of swimmer's itch.
Inquiries may be directed to Deborah Alper at
www.jhsph.edu/TechTransfer, dalper@jhsph.edu or
443-287-0402.
The study was supported by a technology transfer grant
from the Johns Hopkins Bloomberg School of Public Health
and a National Institutes of Health training grant.
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