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ABSTRACT: Dioctophyma renale is a parasite that frequently occurs in animals but rarely in humans. The present report describes the clinical observations of a D. renale infection in a 51-yr-old woman. Its clinical signs and diagnostic findings were unspecific until giant worms were observed in the urine and histological findings confirmed it was a D. renale infection. She refused treatment and died of bilateral renal function failure. This is the first confirmed report to follow the natural progression of D. renale infection in a human. Here, we discuss a conservative therapeutic approach and features associated with this parasitic infection.
Dioctophyma renale has a worldwide distribution, occurring principally in domestic and wild fish-eating carnivores (Celerin and McMullen, 1981; Maxie, 1993), but is sporadically encountered in humans. The life cycle of the worm is very complex. Adult worms pass eggs in the urine of the host. After embryonation in an aquatic environment, the eggs are accidentally ingested by an obligate intermediate host, i.e., an aquatic annelid, where hatching and the first molt occur (Anderson, 2000). A second molt, producing the third stage larvae, occurs about 3 mo after infection (Freitas, 1980). Fish and other animals ingest the annelids with third-stage infective larva and serve as transport hosts. Ingestion of the infective larva in the annelid, or in the transport host by the natural definitive hosts, produces an infection that results in migration of the larva from the intestine to the kidney (Hallberg, 1953). Larvae enter the submucosa of the stomach and penetrate the stomach wall, then enter the right lobe of the liver; from the liver, they migrate directly into the right kidney, which is the maturation site for adult D. renale (Measures, 2001). Humans are accidental definitive hosts (Acha and Szyfres, 1989).
Several documented cases affecting humans have been previously reported. In these reports, however, the clinical presentation is unspecific, i.e., recurrent loin pain (Ignjatovica et al., 2003), subcutaneous nodule (Beaver and Khamboonruant, 1984), and retroperitoneal neoplasm (Beaver and Khamboonruant, 1984). Some cases are asymptomatic and the clinical signs are not suggestive of dioctophymosis. None of the reports provide descriptions of characteristic clinical signs in the early stage. In some dioctophymosis cases, clinical diagnoses are based on the presence of characteristic eggs or worms in...