Control of aquatic leeches (Lymnatis nilotica) using Phytolacca dodecandra (Endod) in Sodo District, Gurage Zone, Southern Nations, Nationalities and Peoples Region, Ethiopia

Abstract

Infestation of cattle by leeches and occasional attacks on humans are becoming serious problems in some parts of Ethiopia. The objective of this study is to investigate the prevalence of leeches in selected streams in Sodo district, Southern Nations, Nationalities and Peoples Region, and to evaluate the efficacy of endod against leeches in field conditions and its impact on non-target aquatic fauna, following the request of the district for intervention. The prevalence of leeches was assessed, based on the number of leeches collected per person per 5 minutes, before application and 24 hrs, 10 days and 30 days after application of endod. Findings from interviews in the local communities revealed that 95{%} of the respondents rated leeches as the major animal health problem in the district and 65{%} of them had seen a human infested by leech at least once in their life. The mean leech count per person per 5 minutes before application of endod ranged from 16.8-38 in different streams. A stock solution of endod berries suspended in water for 16 hrs was continuously applied to various streams so as to maintain a concentration of 20 g/m3 of water for 6 hrs. Application of endod caused mortality of most of the leech population resulting in 97-100{%} reduction, which persisted for minimum of 30 days post-application in most of the streams. Most of the local communities witnessed that endod rendered the treated water bodies free of leeches for 2-3 months. It also caused mortality of tadpoles, frogs and roundworms found in streams. but did not cause any visible toxicity to different water insects. Moreover, no livestock toxicity due to endod was recorded post-application. In conclusion, endod can be used to control leecesh without causing serious toxicity to most of the aquatic fauna, humans or livestock, with continuous application for 6 hrs at a concentration of 20 g/m3. However, care should be taken in using an appropriate concentration and it should not be used in water bodies that contain fish because it is toxic to fish at the dose required to control leeches.