Hydatid disease
Hydatid disease is caused by the Echinococcus species of tapeworm. Dogs are the definitive host for Echinococcus granulosus; foxes are the definitive host for Echinococcus multilocularis (which is not endemic in Australia but is occasionally diagnosed in migrants). Large cysts can form in humans following exposure to tapeworm eggs; these are usually in the liver, but can occur in the lung, brain, bone or muscle.
Treatment of asymptomatic E. granulosus infection may not be required, but monitor cysts for continued growth.
If treatment of cystic disease is required, seek expert advice. Options include open or laparoscopic surgery, ultrasound-guided percutaneous drainage (such as the PAIR technique for liver cysts [puncture, aspiration, injection of a protoscolicidal agent such as hypertonic saline or ethanol, then re-aspiration after at least 15 minutes]) or antimicrobial therapy. Surgery is usually the treatment of choice for symptomatic disease because it is associated with the lowest recurrence rates, especially for liver cysts.
For both surgery and percutaneous drainage (eg PAIR), adjunctive albendazole is recommended; use:
albendazole 400 mg (child older than 6 years: 7.5 mg/kg up to 400 mg) orally with fatty food, 12-hourly, starting 1 week before and continuing for 4 weeks after surgery or PAIR. For dosage adjustment in adults with kidney impairment, see albendazole dosage adjustment. hydatid disease albendazole
Small pulmonary lesions may respond to albendazole alone.
Complicated disease where surgery has failed or is not possible may require more prolonged albendazole. Ensure monitoring for adverse effects is performed in patients on prolonged albendazole therapy—consult a comprehensive source of drug information for more information.
Praziquantel followed by albendazole is used if cysts are spilled during surgery or trauma. Praziquantel can also be used with albendazole before surgery and in complicated hydatid disease.
Alveolar hydatid disease (so-called because of the characteristic budding appearance of the cysts) is caused by E. multilocularis. Management is complex—seek expert advice.