Control of Schistosoma mansoni by the soapberry Endod (Phytolacca dodecandra) in Wollo, northeastern Ethiopia: post-intervention prevalence

Abstract

Objectives: To record the effect of Endod soap and spraying of soaked Endod suspension on the prevalence of human schistosomiasis.

Design: A cross-sectional epidemiological study in which pre- and post-intervention parasitological results were compared.

Setting: Kemise, Bati and Harbu towns in northeastern Ethiopia.

Subjects: The study subjects included all members of the five per cent households systematically selected from the three towns.

Results: In Kemise town, where suspension of ground Endod was sprayed on the stream containing infected snails, the prevalence of the disease was reduced from 59% to 53% and the mean intensity of infection was reduced from 239 eggs per gram (EPG) of faeces to 99 EPG (p < 0.05). In Bati town where Endod soap approach was used, the respective reduction in the prevalence and intensity of infection was from 51% to 43% and from 195 EPG to 162 EPG (p < 0.05). There was also a significant reduction of the disease in the control town probably due to the effects of praziquantel treatment and other factors.

Conclusion: The reduction achieved in the prevalence and intensity of schistosomiasis after an intervention period of four years was limited. This observation corroborates the fact that molluscicides must always be considered as supplementary to chemotherapy in the control of schistosomiasis. Although both approaches can be used, the spraying approach appears to be simpler and more feasible because two or three times yearly application of Endod suspension would suppress snail population and reduce transmission. Nevertheless, the choice as to what approach to use must be made on the basis of community preference, and for some soap-effect of Endod would be attractive