Alveolar hydatid disease

Abstract: During the last 15 years, eight patients with a diagnosis of hydatid cysts of the heart and one patient with a diagnosis of alveolar hydatid disease with intracardiac parasitic thrombus underwent successful operation at La Pitie Hospital. Only five cases had symptoms, and the remaining four cases were diagnosed incidentally. Serologic tests achieved a variety of results and were not determinant. All patients were examined with echocardiography and angiography, and almost all patients underwent magnetic resonance scanning. Sternotomy was the approach used, and all patients underwent operation with cardiopulmonary bypass. Surgical treatment included puncture and aspiration of the cyst content, previous sterilization with hypertonic saline solution, and excision of the cyst with closure of the cavity in seven patients with different concomitant procedures. No case of intraoperative rupture was reported, and the only complication was an atrioventricular block in a patient with a cyst of the left ventricular wall invading the intreventricular septum. There was no operative mortality, and only one late death was observed. No recurrences or associated complications were reported in the late follow-up. (J T HORAC C ARDIOVASC S URG 1994;107:184-90)

Abstract: Nine cases of asymptomatic alveolar hydatid disease (AHD) of the liver were diagnosed in 1985 among Eskimos from the endemic region of western Alaska. The patients were identified by screening with the enzyme-linked immunosorbent assay, using purified Echinococcus multilocularis antigen (Em2 ELISA). Five patients, and one diagnosed earlier (1979), were found to have lesions in which the larval E. multilocularis had died spontaneously at an early stage of infection. Viability was assessed histologically; by the avidinbiotin immunohistochemical method; and in vivo through intraperitoneal inoculation of membranes of the larval cestode into red-backed voles, Clethrionomys rutilus. The results were in agreement with the clinical impression, based on findings by computerized tomography and ultrasound scanning, and on the macroscopic appearance of the lesions, that the cestode was dead. Spontaneous death of E. multilocularis in humans has not been previously reported. The findings show that the Em2 ELISA may be positive in patients having lesions of AHD in which the etiologic agent is no longer viable.

Abstract: The clinical features of 33 cases of alveolar hydatid disease (AHD) in Alaskan Eskimos and a review of the surgical experience with this disease are presented. Among untreated patients, progression of the disease to a fatal outcome was observed in 70%. The primary hepatic lesion resembles cancer, and errors in diagnosis by both the surgeon and pathologist are common. Although surgical resection of the entire primary hepatic lesion offers the only proven curative treatment, only 26% of those explored were resectable. All seven patients resected for cure are alive 6-27 years post-operatively (average survival, 14.7 years). A 5-year experience with continuous mebendazole therapy in the management of five nonresectable cases of AHD indicates that a favorable effect of this drug is being observed. It now appears that Echinococcus infections are no longer the sole province of the surgeon. Although the role of medical therapy is not yet clearly defined, it must be considered in the management of all cases of AHD. The first reported locally-acquired case of AHD in the conterminous United States, and the widespread occurrence and expanding range of E. multilocularis in the north-central United States and south-central Canada, point to the increasing public health importance of alveolar hydatid disease.

Abstract: We investigated a focus of highly endemic Echinococcus multilocularis infection to assess persistence of high endemicity in rural rodents, explore potential for parasite transmission to domestic carnivores, and assess (serologically) putative exposure versus infection frequency in inhabitants of the region. From spring 1993 to spring 1998, the prevalence of E. multilocularis in rodents was 9% to 39% for Arvicola terrestris and 10% to 21% for Microtus arvalis. From June 1996 to October 1997, 6 (7%) of 86 feral dogs and 1 of 33 cats living close to the region tested positive for intestinal E. multilocularis infection. Testing included egg detection by coproscopy, antigen detection by enzyme-linked immunosorbent assay (ELISA), and specific parasite DNA amplification by polymerase chain reaction. Thus, the presence of infected domestic carnivores can increase E. multilocularis exposure risk in humans. A seroepidemiologic survey of 2,943 blood donors in the area used specific Em2-ELISA. Comparative statistical analyses of seroprevalence and clinical incidence showed an increase in Em2-seroprevalence from 1986 and 1996-97 but no increase in clinical incidence of alveolar hydatid disease.

Abstract: Echinococcosis is an infectious disease of humans caused by the larval (metacestode) stage of the cestode species Echinococcus granulosus (cystic echinococcosis or hydatid disease) or Echinococcus multilocularis (alveolar echinococcosis or alveolar hydatid disease). Clinical manifestations depend primarily on localization and size of hepatic lesions and may include hepatomegaly, obstructive jaundice, or cholangitis. Prognostically, alveolar echinococcosis is considered similar to liver malignancies, including a lethality rate of 90% for untreated cases. Diagnosis is based on imaging techniques coupled with immunodiagnostic procedures. Antibody detection tests for E. multilocularis have markedly improved with the use of affinity-purified Em2 antigen and recombinant antigen II/3-10 in enzyme immunoassays. Antigens of corresponding quality for E. granulosus are still unavailable. The detection of circulating antigens and immune complexes in the sera of patients with cystic echinococcosis, the demonstration of in vitro lymphocyte proliferation in response to stimulation with Echinococcus antigens, and the discrimination of serum immunoglobulin isotype activity to various Echinococcus antigens in both cystic and alveolar echinococcosis have been suggested for diagnostic purposes as well as for monitoring patients after treatment. New diagnostic molecular tools include DNA probes for Southern hybridization tests and polymerase chain reaction for the amplification of E. multilocularis and E. granulosus species-specific DNA fragments.