Effect of anthelmintic treatment on the development of resistance in sheep vaccinated or experimentally infected with Dictyocaulus filaria.

This investigation was undertaken to study the immune response of Iraqi sheep vaccinated with Dictyocaulus filaria larvae (Filiraq) and to determine the effect of tetramisole on the development of resistance to reinfection. The findings confirm the effectiveness of Filiraq in conferring protection against experimental infection with D filaria. However, the administration of anthelmintic four weeks after each vaccination interfered with the development of immunity. Termination of D filaria infection at 28 days by tetramisole treatment also prevented the immune response.