 Lice recorded from impala include Damalinia <unk> , D. <unk> , Linognathus <unk> and L. <unk> ; in a study , <unk> ( 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 , <unk> , <unk> , <unk> . Haemonchus , <unk> , Longistrongylus and Trichostrongylus ; some of these showed seasonal variations in density . 
