Curbing cholera

FOR the long-suffering people of
Bangladesh, India and more recently
Latin America, who have to contend
with frequent outbreaks of cholera, here
is a message of hope from Rita Colwell,
a researcher at the Maryland Universit),
Washington. Her research has revealed
that a major outbreak of cholera can be
prevented by keeping a watch on the
growth of a type of aquatic plant known
as the phytoplankton.

Cholera is a threat whenever clean
water is scarce and is caused by a kind
of bacteria called -,qbrio cholerae. Colwell
has discovered that a kind of microscopic aquatic animal, the zooplankton
which also thrives in cold water, is the primary carrier of the cholera virus. An individual zooplankton can carry as
many as 10,000 vibrios and can enter a
human body through water or even
through fish or shellfish picked up
from a pond or river. Colwell has
further observed that the population
of zooplankton increases - usually in
the summers - when an aquatic
plant, the phytoplankton, which
forms the primary diet of the little
animals, grows in abundance. This is
inevitably followed by an outbreak
of cholera. Colwell suggests that
the bloom of phytoplankton should
be monitored by keeping a close
watch on the satellite images of the
earth. And the alarm signals should be
sent vigorously ringing whenever there
is a significant change in the growth of
the phytoplanktons.