Dioctophyme renalis infection



Dioctophyme renale is commonly referred to as “giant kidney worm” [1] because it is the largest helminth [2] to parasitize humans [3] and has the propensity to affect the kidneys. D. renale is distributed worldwide, but is less common in Africa and Oceania [4]. It affects fish eating mammals, particularly mink [1] and dogs [4]. Human infestation is rare, but results in destruction of the kidneys. Upon diagnosis through tissue sampling, the only treatment is surgical excision.


Agent (classification and taxonomy)

Kingdom: Animalia

Phylum: Nemathelminthes

Class: Nematoda

Order: Enoplida

Family: Dioctophymidae

Genus: Dioctophyme

Species: D. renale



Dioctophymosis [4], giant kidney worm, kidney worm infection [5], Dioctophyme renalis infection [6][7]


History of Discovery

Dioctophyme renale was discovered in 1583. Almost two centuries later, in 1782, Johann Goeze first described D. renale upon discovering the worms in a dog kidney. The family Dioctophymidae has only one genus (Dioctophyme), and the name of the genus was in contention (with the possibility of being Dioctophyma) for two hundred years. The issue was finally resolved by the International Commission on Zoological Nomenclature [1] in 1989.


In 2003, D. renale eggs were discovered in six human coprolites in the neolithic site Arbon-Bleiche 3, Switzerland. This location is located near a lake, which likely provided early humans with access to freshwater fish and frogs. The samples were dated from 3,384-3,370 BC, and is evidence that the prevalence of this infection was higher in early human history (before full understanding of proper cooking techniques).[8]


Clinical Presentation in Humans

Individuals with Dicotophyme renalis infection typically present with unspecific symptoms including hematuria [4][6] (blood in urine), nephritis, loin pain [3], renal enlargement, and/or renal colic [4] (intermittent pain in the kidney area), which may result from the rare migration of worms through ureters [1][3][4][6].


Adult worms typically only infect one kidney. The kidney is destroyed because of fibrosis, the development of excess fibrous connective tissue [18]. Renal function is typically limited because the non-infected kidney is usually capable of assuming the increased work. However, parenchymal inflammation (i.e., inflammation of the functional parts of an organ) can lead to death in extreme circumstances.


Transmission/Reservoir/Vector/Incubation Period/Life Cycle

Adult Dioctophyme renale inhabit the kidney (typically the right kidney [2][5]). Females produce eggs which are passed in urine. In aquatic environments, eggs embryonate after 15-100 days [4]. These eggs are ingested by an aquatic oligochaete, hatch, penetrate blood vessels, and develop into a stage three larvae. A paratenic host [10] may then ingest the oligochaete. The oligochaete or paratenic host is then eaten by a definitive host, wherein juveniles penetrate intestinal lining and migrate to the liver. After maturing for approximately 50 days, the juveniles then migrate to the kidneys (typically the right kidney). Upon maturation, D. renale can survive for five years [1].




Intermediate hosts are oligochaete annaelids                     [7][11]


Definitive hosts are carnivorous mammals, notably minks [12], but also includes wolves, coyotes, foxes [13], dogs [14], raccoons, and weasels [5].


Transmission to humans typically occurs upon ingestion of raw or undercooked freshwater fish or frog [3][6].


There are multiple reservoirs for D. renale. Confirmed cases of infection have occurred in minks [14][15], dogs [13], swine, bears, oxen, and humans.[3][4][5][16]



D. renale is the largest helminth to parasitize humans. Adult male worms are 20-40 cm long and 5-6 mm wide; females can grow to 103 cm in length with a width of 10-12mm[3]. Both sexes appear bright red in color and taper at both the anterior and posterior ends. Male D. renale worms have a bursa, which is used to attach to facilitate mating.


Eggs are 60-80 microns x 39-47 microns, contain an embryo, and have characteristic sculpturing of the shell [3]. They have an oval-shape and brownish-yellow hue. Eggs have a thick shell, and the surface appears to be pitted except at the poles.






The only means of obtaining a definitive diagnosis is through the identification of D. renale eggs in a patient’s urine. However, obtaining patient history (i.e., if the patient has consumed undercooked or raw freshwater fish) is an important first step that can be coupled with radiological exams [4] to search for enlarged or calcified kidneys [16]. Urinalysis will likely show hematuria and blood tests may reveal eosinophilia [16].


Management and Therapy

Likely because of the rarity of human cases, there is no standard treatment [5] for D. renale infection in humans. The only means of known means is surgical excision of either adult worms [7] or the infected kidney [6]. Nephrectomy is generally considered extreme for human cases [16].


A physician reportedly used Ivermectin to treat a patient, who was effectively cured [16]. The use of anti-helminth drugs, however, has not yet been evaluated as the proper course of action to treat this infection.



Though D. renale is distributed worldwide, though markedly less frequent in Africa and Oceana, human infection is extremely rare. Regions around the Caspian Sea have the highest number of cases, with the most occurring in Iran [16]. Infections are also most commonly found in areas where freshwater fish is a dietary mainstay.


Non-human infections are more common worldwide, especially in areas of temperate climate. Prevalence in mink populations may be high, such as portions of Ontario [1] or Minnesota [14]. Similarly, some minnow populations may be as high as 50% [4].


Public Health and Prevention Strategies/Vaccines

No public health measures have been undertaken or vaccines developed because of the rarity [11] of human infection. The majority of D. renale infections have resulted from undercooked or raw freshwater fish consumption. Thus, the simple practice of thoroughly cooking fish prior to consumption could be promoted and lead to eradication of D. renale infection in humans.


Useful Web Links/References

[1] "Animal Parasitology." Animal Parasitology. 05 Feb. 2001. Kansas State University. 22 Feb. 2009 <>.

[2] "Urinary System Diseases, Animals." Parasitology Research & Encyclopedic Reference of Parasitology. 22 Feb. 2009 <>.

[3] "Homo sapiens diseases - Metazoa." Molecular Medicine. 22 Feb. 2009 <>.

[4] Palmer, and Reeder. "Kidney Worm: Dioctophymiasis and Eustrongylidiasis." Tropical Medicine Central Resource. International Society of Radiology. 22 Feb. 2009 <>.

[5] "Dioctophyme renale Infection in Bears (Parasitic Disease Summary)." 22 Feb. 2009 <>.

[6] Charisis, N. S., and K. M. Vassalos. An Introduction to FOODBORNE DISEASES & HACCP Systems. Rep. Mediterranean Zoonoses Control Center/World Health Organization. 22 Feb. 2009 <>.

[7] "GIDEON Infectious Diseases." 22 Feb. 2009 <>.

[8] Bailly, M. L., U. Leuzinger, and F. Bouchet. "Dioctophymidae Eggs in Coprolites From Neolithic Site of Arbon-Bleiche 3 (Switzerland)." Journal of Parasitology 89 (2003): 1073-076. Dioctophymidae Eggs in Coprolites From Neolithic Site of Arbon&acirc;&#8364;&#8220;Bleiche 3 (Switzerland). BioOne. 22 Feb. 2009 <>.

[9] Measures, Lena N., and Roy C. Anderson. "Centrachid Fish as Paratenic Hosts of the Giant Kidney Worm, Dioctophyma Renale (Goeze, 1782), in Ontario, Canada." Journal of Wildlife Diseases 21 (1985): 11-19. 22 Feb. 2009 <>.

[10] "Giant Kidney Worm (Dioctophyme renale) in Dogs." Dog, Cat, and Pet Care Tips, Health and Behavior Information by Veterinarians. Veterinary Services Department. 22 Feb. 2009 <>.

[11] Mace, T. F. "Lessions in Mink (Mustela vision) Infected with Giant Kidney Worm (Dioctophyma renale)." Journal of Wildlife Diseases 12 (1976): 88-92. 22 Feb. 2009 <>.

[12] Ribeiro, Carlos Torres, Guilherme Gomes Verocai, and Luiz Eduardo Roland Tavares. "Dioctophyme renale (Nematoda, Dioctophymatidae) Infection in the Crab-eating Fox (Cerdocyon thous) from Brazil." Journal of Wildlife Diseases 45 (2009): 248-50. Dioctophyme renale (Nematoda, Dioctophymatidae) Infection in the Crab-eating Fox (Cerdocyon thous) from Brazil. 22 Feb. 2009 <>.

[13] Nakagawa, Tizianne Larissa Duim Ribeiro, Ana Paula Frederico Rodrigues Loureiro Bracarense, Antonio Carlos Faria Dos Reis, Milton Hissashi Yamamura, and Selwyn Arlington Headley. "Giant kidney worm (Dioctophyma renale) infections in dogs from Northern Paran&Atilde;&iexcl;, Brazil." Veterinary Parasitology 145 (2007): 366-70. Giant kidney worm (Dioctophyma renale) infections in dogs from Northern Paran&Atilde;&iexcl;, Brazil. 22 Feb. 2009 <>.

[14] Mech, L. David, and Shawn P. Tracy. "Prevalence of Giant Kidney Worm (Dioctophyma renale) in Wild Mink (Mustela vison) in Minnesota." The American Midland Naturalist 145 (2001): 206-09. Prevalence of Giant Kidney Worm (Dioctophyma renale) in Wild Mink (Mustela vison) in Minnesota. BioOne. 22 Feb. 2009 <>.

[15] Barros, D. M., M. L. Lorini, and V. G. Persson. "Dioctophymosis in the Little Grison (Galictis cuja)." Journal of Wildlife Diseases 26 (1990): 538-39. 22 Feb. 2009 <>.

[16] Ignjatovic I, Stojkovic I, Kutlesic C, Tasic S: Infestation of the Human Kidney with

            Dioctophyma renale. Urol Int 2003;70:70-73 (DOI: 10.1159/000067695)

[17] "Dioctophyme renale." Encyclopedic Reference of Parasitology. Second ed. 104 vols. Springer, 2001. Parasitology Research & Encyclopedic Reference of Parasitology. 22 Feb. 2009 <>.