 Lice recorded from impala include Damalinia aepycerus , D. elongata , Linognathus aepycerus and L. nevilli ; in a study , ivermectin ( a medication against parasites ) was found to have an effect on Boophilus decoloratus and Linognathus species , though not on Damalinia species . In a study of impala in South Africa , the number of worms in juveniles showed an increase with age , reaching a peak when impala turned a year old . This study recorded worms of genera such as Cooperia , Cooperoides , Fasciola , Gongylonema . Haemonchus , Impalaia , Longistrongylus and Trichostrongylus ; some of these showed seasonal variations in density . 
