Vaccination against the Old World screwworm fly (Chrysomya bezziana)

Chrysomya bezziana is an endemic pest of livestock or a threat to livestock production in large areas of Africa, the Middle East, southern and south-e ast Asia and Australia. Its control is difficult. The feasibility of vaccin ating against this pest has now been explored. In-vitro and in-vivo assays have been established. Using these assays, it has been shown that first ins tar larvae, third instar peritrophic membrane and cardia are all sources of material able to induce immunological reactions in sheep which lead to sig nificant reductions in larval growth. In-vitro assays following vaccination with peritrophic membrane also show larval mortality. Taken together, thee effects lead to an 82% reduction in the weight of recovered larvae in vitr o and 45% reduction in vivo. Preliminary evidence suggests that the mechani sm of protection may be complex.