Dracunculus medinensis: The Guinea Worm

Distribution

Dracunculus medinensis, commonly known as guinea-worm is a parasite of the
dog, horse, cow, wolf, leopard, monkey, and baboon that also commonly infects
man. The majority of humaninfections occur in parts of West Africa, East Africa,
and India.

The larvae, which measure between 500 and 700 micrometers, can live for 6
days in clean water and 2 to 3 weeks in muddy water(see picture below taken
from Peters andGilles 1991).

The larvae are then ingested by Cyclops which actively chase them. Once
ingested, the larvae mature into their infective stage in approximately 14 days
 and can thenreinfect humans.


Pathology

The female guinea-worm lives in the connective tissues of the limbs and
truck where she usually does not cause any noticable pathological conditions
(see X-ray below taken from Peters and Gilles 1991).

After the ingested Cyclops is destroyed by stomach acids the free larvae
penetrate the gut lining and migrate to subcutaneous tissues via the lymphatics.
This process takes approximately 43 days and once in subcutaneous tissue
the worms mature slowly, reaching fulldevelopment in one year. They
then mate and the small male (1.2-2.9 cm long) dies and is absorbed into the
larger female (60cm in length). When the embryos in the female's uterus reach
maturity she migrates to areas of the body in contact with water (90% move
to the feet and legs). Once in these areas the worm penetrates the
skin, extrudes its uterus through its mouth, and discharges larvae into the
water and dies(see picture below taken from Peters and Gilles 1991).

Life Cycle

The guinea-worm like all filarial nematodes goes through six developmental
stages. The however unlike any other filarial parasite that can be transmitted
to humans the infective larvae enter the body
through the ingestion of various species of freshwater crustacea Cyclops
(see picture below taken from Peters and Gilles 1991).


Although heavy infestations in the joint can cause arthritic conditions and
require the removal of the worms (see picture below taken from Peters and
Gilles 1991), most pathology is associated with
infection occuring when the female dies after discharging her larvae.

The death of the worm causes the formation of a sterile abscess, which when
secondarily infected results in cellulitis and local blistering of the skin (see
picture belowtaken from Peters and Gilles 1991).

However, chills fever and local painful swellings commonly precede the
emergence of the worm. D.medinensis has also been found coiled in the hernial
 sac and retroplacentally causing bleeding inpregnancy.
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Diaptomus

Diaptomus is a native freshwater Calanoid Copepod which has been largely
displaced by introduced Copepods.

Neomysis and Zooplankton

The monitoring of neomysis and zooplankton is preformed by the Neomysis and
Zooplankton Survey. The following is a list of zooplankton species for which enough
information is gathered to develop abundance indices. This list is not an all inclusive
list of the species encountered in SanFrancisco Bay and Estuary.

          Neomysis mercedes
          Acartia
          Diptomus
          Euytemora
          Sinocalanus


List of introduced copepods and mysid shrimp.

COPEPOD SPECIES

                          ORIGIN   YEAR INTRODUCED

For more information contact: Jim Orsi at [log in to unmask]
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http://www.delta.dfg.ca.gov/baydelta/monitoring/diaptom.html
NONINDIGENOUS AQUATIC SPECIES IN

                      A UNITED STATES ESTUARY:

       A CASE STUDY OF THE BIOLOGICAL INVASIONS OF THE

                   SAN FRANCISCO BAY AND DELTA
 The San Francisco Estuary can now be recognized as the most invaded aquatic
ecosystem in North America. Now recognized in the Estuary are 212 introduced
species : 69 percent of these are invertebrates, 15 percent
are fish and other vertebrates, 12 percent are vascular plants and 4 percent are protists.
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http://www.glerl.noaa.gov/pubs/abs81.html

VANDERPLOEG, H.A. Seasonal particle-size selection by Diaptomus sicilis in
offshore Lake Michigan. Canadian Journal of Fisheries and Aquatic
 Sciences 38(5):504-517(1981).

     Diaptomus sicilis feeding on offshore Lake Michigan seston exhibited a
relatively  invariant pattern of particle-size selection in 23 separate feeding
experiments conducted  from spring through fall over a 2-yr period.
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http://epaserver.ciesin.org:7777/glreis/glnpo/data/phytop/EPA-905-3-90-003/E
PA-905-3-90-003.html 20. The presence of the oligotrophic rotifer association,
the presence of the oligotrophic crustacean indicator species Diaptomus sicilis
and Limnocalanus macrurus, the predominance of
mesotrophic diatom species, the similarity of the plankton ratio on the
north-south axis and a phytoplankton and zooplankton abundance and biomass
between those of the eutrophic Lake Erieand oligotrophic Lake Huron