[ Introduction | Classification | Synonyms | History of
Discovery | Clinical Presentation | Transmission
| Morphology
]
[ Dianostic Tests | Management
and Treatment | Epidemiology | Public Health
and Prevention | References ]
Introduction
The kidney worm is blood-red in color and is one of the largest of the parasitic roundworms. As their name implies, kidney worms usually occur in the kidneys and more frequently in the right organ than in the left. The presence of the worms in the kidney results in the destruction of the functional tissue of the organ, leaving only a greatly distended and thickened kidney capsule containing worms, fluid and a speculated, bony plate. The only treatment for this parasite is surgical removal.
Photo courtesy of http://cal.vet.upenn.edu/
Classification
Kingdom: Animalia
Phylum: Nemathelminthes
Class:Nematoda
Order: Enoplida
Family: Dioctophymidae
Genus : Dioctophyme
Species: renale
Synonyms
“The Giant Kidney Worm of
Carnivores.”
History of Discovery
There
has been some confusion about the history of discovery of D. renale but formal research
investigating the life cycle of this parasite was started as early as 1782. The
general life cycle of this parasite was known, but further life-cycle
information was discovered in the mid to latter part of the 20th
century.
Clinical Presentation
Ø
Kidney parenchyma
destroyed, capsule distended, calcification occurs
Ø
Adhesions, peritonitis from
worms in body cavity
Ø
Unaffected kidney has
compensatory hypertrophy
Ø
Frequently no clinical
signs because of compensation, but possibly :
Ø
Severe abdominal and lumbar
pain, paresis of the hindquarters
Ø
Sudden weight loss (up to
1/2), anorexia, vomiting
Ø Hematuria, polydipsia, uremia
Ø Severe pain and irritation resulting from adults
attempting to migrate through the ureters.
Transmission
The eggs pass out in the urine
of the final host and develop in water to the infective stage (1 to 7 months).
When the infective egg is swallowed by an oligochaete annelid it hatches and
develops over a period of about 100 days to the third stage larva. If the worm
is eaten by a frog or fish the third stage-larva will encyst in the predator
(paratenic host). When the worm, frog or fish ( paratenic host) is eaten by the
definitive host the larva penetrates the intestinal wall, develop for a while
in the body cavity and then enter the right kidney. The parasite matures to the
adult stage in the kidney destroying the parenchyma of this organ. Eggs are
laid in the kidney and pass out with the urine.
Reservoir:
Generally a parasite of wild mustelids, especially mink;
also reported in canids, bears, raccoons, otters, seals, domestic animals such
as horses, cattle, and swine, and humans (definitive).
Oligochaete annelids (intermediate)
Fish and frogs (paratenic)
Morphology
Adult worms
measure on average:
male: up to 35 cm x 3-6 mm wide
female up to 103 cm x 5-12 mm wide
Both sexes are
blood red in color with a round body
and blunt slightly tapered ends.
Dioctophyme adults. Note the ruler (150 mm). The female worm is at the top of the image.
Photo courtesy of http://www.biosci.ohio-state.edu/~parasite/dioctophyme.html
Eggs - barrel-shaped, shell pitted except at the poles.
Roughly 71-84 x 46-52 microns
Image courtesy of :
Oklahoma State University Parasitology Teaching Resources
Web Site
Incubation period: Eggs embryonate in 2 weeks to 3 months; Juvenile larvae
mature over period of about 50 days in liver parenchyma. They migrate directly
to kidney further mature and may remain alive for up to 5 years.
Diagnostic Test
Ø
Eggs in urine (if adults
are present in the kidney)
Ø
Adults recovered during
laparotomy or hysterectomy (usually when in the abdominal cavity) or at
necropsy
Ø
Radiography
Management and Treatment
Surgical removal of the parasite.
Epidemiology
Cases of D. renale have been reported in virtually every
part of the world with a temperate climate.
In North America, cases are primarily found in Michigan, Minnesota and
Wisconsin. D. renale is a very rare parasite of humans, having been reported
only 3 times.
Public Health Prevention Strategies
Human infections have been rare, with
only three on record. In these cases worms were found in the kidneys and larvae
were found in subcutaneous nodules. These cases are of unknown etiology, but
are thought to have been caused by the consumption of raw fish. Because the rarity of dioctophyme renale
infection in humans, no public health measures have been taken.
References:
1)
Barros DM, Lorini ML, Persson VG, Dioctophymosis
in the little grison (Galictis cuja). Journal of Wildlife Discovery 1990
Oct;26(4):538-9
2)
Crichton VJ, Urban RE, Dioctophyme renale (Goeze, 1782)
(Nematoda: Dioctophymata) in Manitoba mink Canandian Journal of Zoology
1970 May;48(3):591-2
3) Fernando, SS, The giant kidney worm (Dioctophyma
renale) infection in man in Australia. American Journal of
Surgical Pathology. 1983
Apr;7(3):281-284
4) Mace TF,
Anderson RC, Development of the giant kidney worm, Dioctophyma renale (Nematoda: Dioctophymatoidea). Canadian Journal of Zoology. 1975
Nov;53(11):1552-68.
5) Measures LN, Anderson RC, Centrarchid fish
as paratenic hosts of the giant kidney worm, Dioctophyma renale in Ontario, Canada. Journal of Wildlife Discovery . 1985
Jan;21(1):11-9.
6) Sun T, Turnbull A, Lieverman PH, Sternberg
SS. Giant kidney worm (Dioctophyma renale) infection mimicking
retroperitoneal neoplasm. American Journal of Surgical
Pathology. 1986 Jul;10(7):508-12.
8) http://www.missouri.edu/~vmicrorc/Nematoda/Enoplids/Drenale.htm
9)
http://cal.vet.upenn.edu/dxendopar/parasitepages/dioctophymatoides/d_renale.html#adult
10)
http://animaldiversity.ummz.umich.edu/nematoda/secernentea/ascaridida/dioctophymatidae/dioctophyme_renale.html
11)
http://www.ksu.edu/parasitology/classes/625nematode18.html
12) http://www.cabi-publishing.org/Bookshop/Readingroom/0851994210/4210Ch8.pdf