High oral doses of mebendazole interfere with growth of larval Echinococcus multilocularis lesions.

The natural development of the larval stage of Echinococcus multilocularis in man has been studied in 7 patients after presumed radical operation 2 8/12-11 2/12 years prior to detection of a relapse. The volumes of the recurring lesions were assessed by CT-scanning, and assuming linear growth a median increase of 14.8 ml/year (range 3.8-220 ml/year) was calculated. In 6 patients treated for a median duration of 4 5/12 years with high oral doses of mebendazole a median growth rate of -3.0 ml/year (range-470- + 10.2 ml/year) was found, which differed significantly from the natural growth rate (P less than 0.01). Although the patients improved clinically, there was evidence of persistent infection. These data are the first controlled evidence that high oral doses of mebendazole may be parasitostatic in alveolar echinococcosis in man. Although not curative, this pharmacological effect appears to be clinically beneficial.