Optimal duration of preoperative anti‐helminthic therapy for pulmonary hydatid surgery

Background:  The optimal duration of preoperative anti-helminths for prevention of recurrences in pulmonary hydatidosis is unclear, although 1–3 weeks of therapy is routinely used. Methods:  Forty-five patients of pulmonary hydatid disease were randomly assigned into four groups to receive either 0, 2, 4 or 8 weeks of preoperative albendazole (ABZ) and praziquantel (PZQ). Viability of the scolices in the fluid harvested at surgery (methylene blue staining) and ability to produce peritoneal hydatids in mice (intra-peritoneal inoculation) were compared in different groups. Results:  The percentage viability of the scolices as a whole was significantly (P < 0.001) lower in the treated cysts (n= 36, mean 43.5 ± 35.69) compared with the untreated cysts (n= 8, mean 94.75 ± 7.21). The viability progressively decreased with increasing durations of chemotherapy (P < 0.001). Mean percentage viability of scolices was 88.72 ± 4.91% in patients treated for 2 weeks (n= 12), 38.09 ± 9.10% after 4 weeks (n= 11) and 8.1 ± 9.23% after 8 weeks (n= 14). Intra-peritoneal mice inoculation was positive in 90% of the cysts that received therapy for 2 weeks or less and none of the patients who received therapy for 8 weeks had a positive inoculation. Conclusions:  Preoperative combination therapy with ABZ and PZQ effects a scolicidal response which increases with the increasing duration of the preoperative chemotherapy, and a 4-week course of the combination chemotherapeutic agents seems to be the minimum required duration for ensuring scolicidal activity enough to prevent spillage-induced recurrences following pulmonary hydatidosis.