Giant Kidney Worm

(Dioctophyme renale)

Dioctophyme renale is a large enoplid nematode that infects the kidneys of dogs and occasionally cats. It is zoonotic.

Parasite species: Dioctophyme renale
Common name: Giant kidney worm
Hosts: Wild carnivores, dogs, and cats
Pre-patent period: 3.5-6 months
Location in the host: Kidneys
Distribution: Worldwide
Transmission route: Ingestion of intermediate (aquatic worms) or paratenic hosts (fish, crustaceans, frogs or other amphibians)
Zoonotic: Yes

Distribution

Dioctophyme renale is found worldwide but is less common in Africa and Oceania.

Clinical signs

Dioctophyme renale infection in cats may cause a range of clinical manifestations, varying from subclinical to severe life-threatening disease. Clinical signs may include weakness, jaundice, dehydration, ascites and prostration. Parasite invasion into the peritoneal cavity can lead to adhesions, peritonitis and, eventually, death [1].

Diagnosis

Dioctophyme renale infections in cats can be confirmed by finding eggs in urine samples. Eggs (approximately 62-75 x 36-53 µm) (Fig. 1) have elliptical shape, generally with symmetrical and clear bipolar plugs, covered by a thick, rough shell [2]. Imaging techniques (e.g. radiography and ultrasonography) may help in revealing the presence of adult worms in the kidneys. Nonetheless, the diagnosis is often done during surgery for other reasons or eventually during necropsy (Fig. 2).

Figure 1. Egg of Dioctophyme renale in a urine sample (Image credit: Dr. G. Perez-Tort)
Figure 2. Adult Dioctophyme renale worms excised from kidney of a dog (Image credit: Dr. G. Perez-Tort)

Treatment

The surgical removal of worms from the kidney is the most effective and commonly recommended treatment against D. renale.

Prevention and Control

The control of D. renale may be achieved by preventing cats from hunting and eating aquatic worms, fish, crustaceans, frogs or other amphibians.

Public health considerations

Cases of human infection by D. renale have been reported. The eggs shed by infected dogs and cats are not directly infective for humans. Humans become infected after eating raw or insufficiently cooked fish or frogs (paratenic hosts).

References

[1] Verocai GG, Measures LN, Azevedo FD, Correia TR, Fernandes JI, Scott FB. Dioctophyme renale (Goeze, 1782) in the abdominal cavity of a domestic cat from Brazil. Vet Parasitol. 2009;161:342-344.

[2] Pedrassani D, Lux Hoppe EG, Avancini N, do Nascimento AA. Morphology of eggs of Dioctophyme renale Goeze, 1782 (Nematoda: Dioctophymatidae) and influences of temperature on development of first-stage larvae in the eggs. Rev Bras Parasitol Vet. 2009;18:15-19.