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Dracunculus
Picture:
Dracunculus medinensis, the cause of
dracunculiasis
Source
--Genus of nematode
parasites
--Latin for “little
dragon”
--Family -
Dracunculidae
--7 main species
D. insignis – dogs and wild
carnivores
D. medinensis -- humans, dogs,
cattle, horses
--Also known as “Guinea
Worm”
Life Cycle of D.
medinensis
Picture source
D. medinensis emerges through an ulcer
on the skin after one or two years of
infection. When the person with the
emergent worm enters drinking water, the
worm releases larvae into the water.
Microscopic water fleas (Cyclops)
then ingest the larvae.
Cyclops
The larvae develop into
the infective stage within 10-14 days.
--Humans become
infected by drinking water. Human stomach
acid digests flea, but not the guinea worm.
Then the worm can enter body cavity via
small intestine and develop further.
--Male worm = 1-3 cm
--Female worm = 60-100
cm long (like a strand of spaghetti)
During next 10-14
months, the male and female will copulate.
The male dies and is absorbed into female.
--Female can contain
1000s of larvae and resides in the
connective tissues of limbs and trunk.
--Generally no
pathological conditions
Finally, the female
migrates to part of body where it will
emerge
--90% of cases = lower
limbs
Death of female
responsible for the following…
--Blister develops on
skin and ruptures within 72 hours – thus,
exposing the worm
--Blister becomes an
ulcer
--Immersion in water to
relieve burning
--Female is capable of
releasing larvae for several days and the
cycle repeats. Repeat Infection is quite
common
Picture:
Emerging D. medinensis
Source
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Cyclops: Vector of Dracunculus
Picture Source
One of the most common genera
of freshwater copepods
--100 species
--0.5-5mm long with large red
or black eye
They have even made it into
popular culture
Sheldon J. Plankton of
SpongeBob SquarePants
Picture Source
Affected Communities
--Generally tropical regions
that have one or more annual dry seasons
--Infection acquired from a
stagnant drinking water source like ponds
and shallow wells
--In 2005, all known infections
in sub-Saharan Africa (Ghana, Sudan, Nigeria)
In those countries…
Nigeria Map Source
 --58%
bed-ridden for at least one month after emergence
--Nigeria = half of adult
members of family suffered from dracunculiasis in
one year
--Sudan = children of stricken
parents 3x as likely to be malnourished
Map below: Sudan
Source
Eradication efforts, however,
are still considered to be extremely successful
Epidemiology
--11 endemic countries in 2004
--9 endemic countries in 2005
(Benin and Mauritania dropped off list)
Endemic countries reported 10,
674 cases in 2005
Burkina Faso, Cote d’Ivoire,
Ethiopia, Ghana, Mali, Niger, Nigeria, Sudan, Togo
Ghana and Sudan reported 9550
(90% total)
Ghana – 3981 (37%)
Sudan – 5569 (52%)
Non-endemic cases (brings tally
to 12)
Uganda (9)
Kenya (2)
Benin (1)
Last cases remain most
difficult
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