Activity of cyclosporine^® against <i>Schistosoma mansoni</i> cercariae

Abstract

Schistosomiasis is a helminth disease that affect many people all over the world causing illnesses there by preventing people from farming and performing other activities, and at times gives rise to malignancies which could be fatal. Despite the successes of treatment of schistosomiasis by paraziquantel and some aspects of molluscicides, the disease remains one of the most  important public health problems in many developing countries including Nigeria. This study attempted to interrupt the life cycle at the cercarial stage through administration of cyclosporine to halt the reoccurrence of infection. Snail intermediate host  (Biomphalaria pfeifferi)were obtained from the stream (Farin Gada, Jos, Plateau State), examined for cercariae by exposure to sunshine for 30 minutes andcercariae obtained were estimated using Neubauer’s counting chamber before toxicity test was conducted. The schistosomicidal properties of cyclosporine were tested invitro against Schistosoma mansoni cercariae. A stock solution of 6.13 mg/L was obtained after a range finding test from which serial dilutions were made to obtain concentrations of 3.06, 2.06, 1.06 and 0.06 mg/L respectively while the control had no test drug (0.00 mg/L). Each of these concentrations was applied in duplicate replication to 10 ml of water containing 15 freshly shed cercariae. Viability of the cercariae were monitored at different time intervals. Data obtained was subjected to regression analysis to find line of best fit. The cercariae percentage mortalities were calculated and transformed into probit mortality and the 12 hour LC₅₀ and 95% confidence limits were  determined. The 12hr LC₅₀ was calculated to be 1.08 mg/L with 95% upper and lower confidence limits as 2.08 and 0.53mg/L respectively while the LT₅₀ was calculated to be 2.75 hours. The result revealed a strong and positive correlation (r² = 0.59) between the concentration of cyclosporine and probit mortality value which indicates strong larvicidal effects against the  cercariae. The result also revealed potential anticercarial activities of cyclosporine based on the acute toxicity concentration (LC₅₀) and the lethal time (LT₅₀) on S.mansoni cercariae which would rekindle public health interest for the need to curb the risk of reinfection being a major problem of schistosomiasis management globally.

Keywords: B. pffeiferi; S. mansoni; cercariae; cyclosporine; anticercarial.