SUMMARY ●Echinococcus granulosus infection is initially asymptomatic and may remain so for many years. Subsequent clinical features and complications depend upon the site and size of the cyst(s). The liver and lungs are affected in approximately 67 and 25 percent of cases, respectively. Most patients have single-organ involvement, and a single cyst is present in more than 70 percent of cases. The long-term outcome is variable and many patients remain asymptomatic
●Echinococcus multilocularis infection is more likely to be symptomatic than E. granulosus infection. The most common clinical manifestations include right upper quadrant discomfort, malaise, and weight loss, and the picture may mimic that associated with hepatocellular carcinoma. In the absence of treatment, more than 90 percent of patients with alveolar echinococcosis die within 10 years of the onset of clinical symptoms.
●The diagnosis of echinococcosis is typically established by ultrasound imaging (in combination with serologic testing (usually enzyme-linked immunosorbent assay). Hydatid disease is probable in the setting of ultrasound demonstrating infoldings of the inner cyst wall, separation of the hydatid membrane from the wall of the cyst, or hydatid sand. E. multilocularis lesions may have an irregular contour and may be difficult to differentiate from tumor.
●Diagnostic judgment must take into consideration the limitations of serologic testing. The likelihood of a positive serology depends on cyst location and viability. Patients with liver cysts are more likely to be seropositive than patients with lung cysts. Serologic assays are less likely to be positive in the setting of calcified or nonviable cysts. In addition, the sensitivity and specificity of serology is greater for E. multilocularis than for E. granulosus.
●Percutaneous aspiration or biopsy should be reserved for situations when other diagnostic methods are inconclusive because of the potential for anaphylaxis and secondary spread of the infection. If aspiration is required, it should be performed under ultrasound or CT guidance. Complications can be minimized by concurrent administration of albendazole and praziquantel.
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