Tegumental changes in adult Schistosoma mansoni harbored in mice treated with artemether

A detailed temporal examination was made of alterations induced by artemether in the tegument of adult Schistosoma mansoni worms using scanning electron microscopy (SEM). Mice infected with S. mansoni cercariae 42 days previously were treated intragastrically with artemether at a single dose of 400 mg/kg. Groups of 3 mice were killed at 24 hr, 72 hr, and 7 days after treatment; the worms were collected by perfusion and examined by SEM. Twenty-four hours after artemether treatment, focal damage to the tubercles on the tegumental surface of male worms was seen. In both male and female worms, there was focal swelling and fusion of tegumental ridges, and sometimes peeling. After 72 hr, the damage to the tegument had increased, especially in female worms, with extensive swelling, fusion, and peeling of the tegumental ridges. In the most severely damaged worms, host leukocytes were seen to be adhered to the damaged tegument. Damage to the oral sucker was also occasionally seen in both male and female worms. Seven days after treatment, the appearance of the tegument had returned to normal in some male and female worms, whereas others still showed apparent damage. The results demonstrate that artemether damages the tegument of adult S. mansoni, and the intensity of damage is more severe in female worms than in males.