The seasonal incidence of the major nematode genera recovered from sheep, cattle, impala and blesbok in the Transvaal.

The seasonal incidence of helminth infestation in sheep, cattle, impala and blesbok was determined from fluctuations in the worm burdens of these animals exposed to natural infestation at particular localities in the Transvaal and slaughtered at various fairly regular intervals. The nematodes considered to be of major importance were Haemonchus spp. and Trichostrongylus spp. in all four hosts, Ostertagia spp. in sheep, Longistrongylus spp. in impala, Cooperia spp. in sheep, cattle and impala, Cooperioides spp. in impala, Impalaia spp. in impala and blesbok and Oesophagostomum spp. in sheep, cattle and impala.